Overview

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The Adafruit Feather nRF52 Pro is our latest Bluetooth Low Energy board for advanced projects and users who want to use a fully open source Bluetooth Low Energy 5.0 stack. It has a native-bluetooth chip, the nRF52832, as well as built in USB Serial and battery charging!  We have other boards in the Feather family, check'em out here.

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This is a special Feather - unlike the rest of the Feather family, this board is not for use with Arduino IDE. Instead, it is for use with Mynewt only! We have programmed it with the Mynewt bootloader and updated the hardware to add an SWD connector and an additional DFU button. If you want to use the nRF52 with Arduino IDE please check out the Bluefruit nRF52 Feather which works out-of-the-box with our Arduino board support package. This Feather is for advanced users only, you will be interacting with the Mynewt RTOS rather than Arduino and you cannot easily go back-and-forth without an SWD programmer.

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This chip has twice the flash, SRAM and performance of the earlier nRF51-based modules, and can do a lot of heavy lifting. That extra processing power and memory means you can now run an RTOS for fast development of complex projects. This board was designed to work with the Apache Mynewt operating system, which is released by the Apache Foundation under the permissive and commercial-friendly Apache license. Apache Mynewt includes a number of professionally written networking stacks (BLE 5.0, OIC/OCF, etc.), development tools, and professional project management features like a secure bootloader that allows you to cryptographically sign firmware images and verify them during device updates.

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The Adafruit Feather nRF52 Pro ships pre-programmed with the Mynewt serial bootloader that allows you to flash firmware to the device directly from the command-line using the on-board USB Serial converter and the 'newtmgr' tool, so you can get started right away with no additional hardware required. For more advanced debugging, however, you can use a Segger J-Link and the on-board SWD debug connector, which gives you access to a more powerful set of development tools and options.

Features:

  • ARM Cortex M4F (with HW floating point acceleration) running at 64MHz
  • 512KB flash and 64KB SRAM
  • Built in USB Serial converter for fast and efficient programming and debugging
  • Bluetooth Low Energy compatible 2.4GHz radio (Details available in the nRF52832 product specification)
  • FCC / IC / TELEC certified module
  • Up to +4dBm output power
  • 1.7v to 3.3v operation with internal linear and DC/DC voltage regulators
  • 19 GPIO, 8 x 12-bit ADC pins, up to 12 PWM outputs (3 PWM modules with 4 outputs each)
  • Pin #17 red LED for general purpose blinking
  • Power/enable pin
  • Measures 2.0" x 0.9" x 0.28" (51mm x 23mm x 8mm) without headers soldered in
  • Light as a (large?) feather - 5.7 grams
  • 4 mounting holes
  • Reset button
  • SWD connector for debugging
  • 100% open source firmware when used with Apache Mynewt

Bluetooth Low Energy is the hottest new low-power, 2.4GHz spectrum wireless protocol. In particular, its the only wireless protocol that you can use with iOS without needing special certification and it's supported by all modern smart phones. This makes it excellent for use in portable projects that will make use of an iOS or Android phone or tablet. It also is supported in Mac OS X and Windows 8+.

To make it easy to use for portable projects, we added a connector for any of our 3.7V Lithium polymer batteries and built in battery charging. You don't need a battery, it will run just fine straight from the micro USB connector. But, if you do have a battery, you can take it on the go, then plug in the USB to recharge. The Feather will automatically switch over to USB power when it's available. We also tied the battery thru a divider to an analog pin, so you can measure and monitor the battery voltage to detect when you need a recharge.

The Power of Bluefruit LE

The nRF52 Pro uses an nRF52832 chipset from Nordic, which can be used as both a main microcontroller and a bluetooth low energy interface. For most people, they'll be very happy to use the standard Nordic UART RX/TX connection profile - example code is provided! In this profile, the Bluefruit acts as a data pipe, that can 'transparently' transmit back and forth from your iOS or Android device. You can use our iOS App or Android App, or write your own to communicate with the UART service.

The board is capable of much more than just sending strings over the air!  Thanks to the Apache Mynewt operating system, you have full control over how the device behaves, including the ability to define and manipulate your own GATT Services and Characteristics, or change the way that the device advertises itself for other Bluetooth Low Energy devices to see.

Use the Bluefruit App to get your project started

Using our Bluefruit iOS App or Android App, you can quickly get your project prototyped by using your iOS or Android phone/tablet as a controller. This data can be read over BLE and processed directly by the nRF52 microcontroller

Comes fully assembled and tested, with a USB Serial bootloader that lets you quickly use it from the command line. We also toss in some header so you can solder it in and plug into a solderless breadboard. Lipoly battery and MicroUSB cable not included (but we do have lots of options in the shop if you'd like!)

Bluetooth Certification Warning

Because of complex and expensive Bluetooth SIG certification requirements, the nRF52 Pro doesn't ship with any default Bluetooth functionality on the post-production firmware, since at present the Mynewt BLE stack has not gone through the certification process with the Bluetooth SIG. We aren't able to ship BLE functionality out of the box without this certification. In order to use Mynewt in a production product, you will need to go through the certification process for your product, although you are free to develop locally with Mynewt in a test environment.

The only Bluetooth Low Energy stack certified to run on the nRF52 modules with no additional work on your part is the Nordic SoftDevice, which is used in the Arduino variant of these boards and can be flashed onto the nRF52 Pro using your choice of ARM SWD debugger, such as the Segger J-Link.

When the Mynewt stack is certified by the Bluetooth SIG (no ETA on if or when that will happen since it's a long and expensive process), Bluetooth functionality will be enabled on shipping devices, but at present only USB Serial is used in the default firmware on production devices, and the Nordic SD should be used in commercial products if you are not able to go through the certification process yourself. There are no HW restrictions on the nRF52 Pro boards, we simply have our hands tied on what we can ship and claim coming off the production line.

UPDATE (Sept 17 2017): Runtime, one of the main contributors to the Mynewt core codebase, have contracted an external company to certify nimble (the Mynewt BLE stack). Once the certification process is completed, the results and certificate details will be posted here.

Device Pinout

microcontrollers_Feather_NRF52_Pinout_v1.2-1.png
microcontrollers_nRF52Pinout.png
Please note that the nRF52832 uses a USB serial adapter to RXD/TXD are with respect to the nRF52

Special Notes

The following pins have some restrictions that need to be taken into account when using them:

  • PIN_DFU / P0.20: If this pin is detected to be at GND level at startup, the board will enter a special serial bootloader mode and will not execute any user code, going straight into bootloader mode. If you wish to use this pin as a standard GPIO, make sure that it is pulled high with a pullup resistor so that your code will execute normally when the MCU starts up.
  • P0.31 / A7: This pin is hard wired to a voltage-divider on the LIPO battery input, allow you to safely measure the LIPO battery level on your device. If possible, you should avoid using this pin as an input because you will lose the ability to read the battery voltage. You can use it as an output just make sure to switch the pin to analog input when you want to do the battery read, then back to output when toggling pins
  • FRST/P0.22: Setting this pin to GND at startup will cause the device to perform a factory reset at startup, erasing and config data as well as the user sketch. At the next reset, you should enter serial bootloader mode by default, since no user sketch will be present. You can use this to recover 'bricked' boards, but if you don't wish to do this be careful not to have FRST low at startup. By default, a weak internal pull-up resistor is enabled on this pin during the bootloader phase. FRST does not work with Mynewt bootloader !!

Power Pins

  • 3.3V Output: This two pins are connected to the output of the on board 3.3V regulator. They can be used to supply 3.3V power to external sensors, breakouts or Feather Wings.
  • LIPO Input (VBAT): This is the voltage supply off the optional LIPO cell that can be connected via the JST PH connector. It is nominally ~3.5-4.2V.
  • VREG Enable: This pin can be set to GND to disable the 3.3V output from the on board voltage regulator. By default it is set high via a pullup resistor.
  • USB Power (VBUS): This is the voltage supply off USB connector, nominally 4.5-5.2V.

Analog Inputs

The 8 available analog inputs can be configured to generate 8, 10 or 12-bit data (or 14-bits with over-sampling), at speeds up to 200kHz (depending on the bit-width of the values generated), based on either an internal 0.6V reference or the external supply.

The following default values are used:

  • Default voltage range: 0-3.6V (uses the internal 0.6V reference with 1/6 gain)
  • Default resolution: 10-bit (0..1023)
Unlike digital functions, which can be remapped to any GPIO/digital pin, the ADC functionality is tied to specified pins, labelled as A* in the image above (A0, A1, etc.).

PWM Outputs

Any GPIO pin can be configured as a PWM output, using the dedicated PWM block.

Three PWM modules can provide up to 12 PWM channels with individual frequency control in groups of up to four channels.

Please note that DMA based PWM output is still a work in progress in the initial release of the nR52 BSP, and further improvements are planned here.

I2C Pins

I2C pins on the nRF52832 require external pullup resistors to function, which are not present on the Adafruit nRF52 Feather by default. You will need to supply external pullups to use these. All Adafruit I2C breakouts have appropriate pullups on them already, so this normally won't be an issue for you.

Assembly

We ship Feathers fully tested but without headers attached - this gives you the most flexibility on choosing how to use and configure your Feather

Header Options!

Before you go gung-ho on soldering, there's a few options to consider!

The first option is soldering in plain male headers, this lets you plug in the Feather into a solderless breadboard

Another option is to go with socket female headers. This won't let you plug the Feather into a breadboard but it will let you attach featherwings very easily

A few Feather boards require access to top-side components like buttons or connectors, making stacking impractical. Sometimes you can stack in the opposite order—FeatherWing underneath—or, if both Feather and Wing require top-side access, place the boards side-by-side with a FeatherWing Doubler or Tripler.

We also  have 'slim' versions of the female headers, that are a little shorter and give a more compact shape

Finally, there's the "Stacking Header" option. This one is sort of the best-of-both-worlds. You get the ability to plug into a solderless breadboard and plug a featherwing on top. But its a little bulky

Soldering in Plain Headers

Prepare the header strip:

Cut the strip to length if necessary. It will be easier to solder if you insert it into a breadboard - long pins down

Add the breakout board:

Place the breakout board over the pins so that the short pins poke through the breakout pads

And Solder!

Be sure to solder all pins for reliable electrical contact.

(For tips on soldering, be sure to check out our Guide to Excellent Soldering).

Solder the other strip as well.

You're done! Check your solder joints visually and continue onto the next steps

Soldering on Female Header

Tape In Place

For sockets you'll want to tape them in place so when you flip over the board they don't fall out

Flip & Tack Solder

After flipping over, solder one or two points on each strip, to 'tack' the header in place

And Solder!

Be sure to solder all pins for reliable electrical contact.

(For tips on soldering, be sure to check out our Guide to Excellent Soldering).

You're done! Check your solder joints visually and continue onto the next steps

Native Installation (OS X)

Mynewt relies on two command line utilities (newt and newtmgr), both of which are described elsewhere in this learning guide, as well as the presence of an ARM cross-compiling toolchain (arm-none-eabi-gcc, etc.).

Both of these need to be installed and available on your system to work with Mynewt projects.

Install newt and newtmgr Binaries

Binary versions of the command-line tools are available from Apache.

Before you start, you will need to add the JuulLabs-OSS/homebrew-mynewt 'tap' to brew, which can be done as follows:

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$ brew tap JuulLabs-OSS/mynewt
$ brew update

Install newt

The full setup guide is available here: https://mynewt.apache.org/latest/newt/install/newt_mac.html

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$ brew install mynewt-newt
==> Installing mynewt-newt from juullabs-oss/mynewt
==> Downloading https://github.com/juullabs-oss/binary-releases/raw/master/mynewt-newt-tools_1.5.0/mynewt-newt-1.5.0.sierra.bottle
==> Downloading from https://raw.githubusercontent.com/JuulLabs-OSS/binary-releases/master/mynewt-newt-tools_1.5.0/mynewt-newt-
######################################################################## 100.0%
==> Pouring mynewt-newt-1.5.0.sierra.bottle.tar.gz
/usr/local/Cellar/mynewt-newt/1.5.0: 3 files, 8.1MB

You can test the install with:

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$newt version
Apache Newt version: 1.5.0

Install newtmgr

The full setup guide is available here: https://mynewt.apache.org/latest/newtmgr/install/install_mac.html

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$ brew install mynewt-newtmgr
==> Installing mynewt-newtmgr from runtimeco/mynewt
==> Downloading https://github.com/runtimeco/binary-releases/raw/master/mynewt-newt-tools_1.5.0/mynewt-newtmgr-1.1.0.sierra.bottle.tar.gz
==> Downloading from https://raw.githubusercontent.com/runtimeco/binary-releases/master/mynewt-newt-tools_1.5.0/mynewt-newtmgr-1.5.0.sierra.bottle.tar.gz
######################################################################## 100.0%
==> Pouring mynewt-newtmgr-1.5.0.sierra.bottle.tar.gz
/usr/local/Cellar/mynewt-newtmgr/1.5.0: 3 files, 17.8MB

You can test the install with:

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$ newtmgr help
Newtmgr helps you manage remote devices running the Mynewt OS

Usage:
  newtmgr [flags]
  newtmgr [command]

Available Commands:
  config      Read or write a config value on a device
  conn        Manage newtmgr connection profiles
  crash       Send a crash command to a device
  datetime    Manage datetime on a device
  echo        Send data to a device and display the echoed back data
  fs          Access files on a device
  help        Help about any command
  image       Manage images on a device
  log         Manage logs on a device
  mpstat      Read mempool statistics from a device
  reset       Perform a soft reset of a device
  run         Run test procedures on a device
  stat        Read statistics from a device
  taskstat    Read task statistics from a device

Flags:
  -c, --conn string       connection profile to use
  -h, --help              help for newtmgr
  -l, --loglevel string   log level to use (default "info")
      --name string       name of target BLE device; overrides profile setting
  -t, --timeout float     timeout in seconds (partial seconds allowed) (default 10)
  -r, --tries int         total number of tries in case of timeout (default 1)

Use "newtmgr [command] --help" for more information about a command.

Install an ARM Cross-Compiling Toolchain

In order to build and debug ARM binaries, you will also need to install a cross-compiling toolchain targeting the ARM architecture.

Thankfully, pre-built binaries are also available in brew (used to install newt and newtmgr), as described in the setup guide below:

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$ brew tap PX4/homebrew-px4
$ brew update
$ brew install gcc-arm-none-eabi-49

You can test the installation with the following command (making sure that the version listed is 4.9!):

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$ arm-none-eabi-gcc --version  
arm-none-eabi-gcc (GNU Tools for ARM Embedded Processors) 4.9.3 20150529 (release) [ARM/embedded-4_9-branch revision 224288]
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Optional: Install the OpenOCD Debugger

If you wish to debug or flash your projects with a Segger J-Link, you will also need to install the OpenOCD debug tool via the following steps:

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$ brew install openocd

If you see one of these errors:

  • Library not loaded: /usr/local/lib/libusb-0.1.4.dylib
    Run: brew install libusb-compat
  • Library not loaded: /usr/local/opt/libftdi/lib/libftdi1.2.dylib
    Run: brew install libftdi
  • Library not loaded: /usr/local/lib/libhidapi.0.dylib
    Run: brew install hidapi

Make sure you have at least version 0.10.0, which can be verified with the following command:

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$ openocd --version
Open On-Chip Debugger 0.10.0
Licensed under GNU GPL v2
For bug reports, read
	http://openocd.org/doc/doxygen/bugs.html

Optional: Install Segger J-Link Drivers

If you wish to use the newt load or newt debug commands and a Segger J-Link, you will need to install the Segger J-Link drivers as well.

You will need to go to the Segger J-Link Downloads page and download the 'J-Link Software and Documentation pack for MacOSX' installer:

adafruit_products_Screen_Shot_2017-08-17_at_23.39.07.png

Once downloader, run the installer and the JLinkExe and related J-Link commands that Mynewt relies on will be available from the command-line.

Optional: Install minicom

Much of the interaction with your Mynewt device will happen over the serial port, including working with Shell-based commands on your device.

A relatively easy to use command line application to work with serial port connections is minicom, which is used throughout this learning guide. It can be installed from the command-line with the following command:

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$ brew install minicom

You can establish a serial connection via minicom with the following command (adjusting the /dev/tty device name as appropriate):

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$ minicom -D /dev/tty.SLAB_USBtoUART

Native Installation (Linux)

Mynewt relies on two command line utilities (newt and newtmgr), both of which are described elsewhere in this learning guide, as well as the presence of an ARM cross-compiling toolchain (arm-none-eabi-gcc, etc.).

Both of these need to be installed and available on your system to work with Mynewt projects.

Install newt and newtmgr Binaries

Binary versions of the command-line tools are available from Apache.

The full setup guide is available here: https://mynewt.apache.org/latest/newt/install/newt_linux.html

In summary, copy following commands and paste it (one line each time) into your terminal to add newt's public key and deb package to your apt repository for installation.

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$ wget -qO - https://raw.githubusercontent.com/JuulLabs-OSS/debian-mynewt/master/mynewt.gpg.key | sudo apt-key add -
$ sudo tee /etc/apt/sources.list.d/mynewt.list <<EOF
deb https://raw.githubusercontent.com/JuulLabs-OSS/debian-mynewt/master latest main
EOF
$ sudo apt-get update
$ sudo apt-get install newt
$ sudo apt-get install newtmgr

Check your installation with version command

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$ newt version
Apache Newt version: 1.5.0
$ newtmgr version
Apache Newtmgr 1.5.0

Install an ARM Cross-Compiling Toolchain

In order to build and debug ARM binaries, you will also need to install a cross-compiling toolchain targeting the ARM architecture.

Thankfully, pre-built binaries are available, as described in the setup guide below:

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$ sudo apt-get remove binutils-arm-none-eabi gcc-arm-none-eabi 
$ sudo add-apt-repository ppa:team-gcc-arm-embedded/ppa
$ sudo apt-get update 
$ sudo apt-get install gcc-arm-none-eabi

Optional: Install the OpenOCD Debugger (Segger J-Link)

If you wish to debug or flash your projects with a Segger J-Link, you will also need to install the OpenOCD debug tool via the following steps:

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$ sudo apt-get install openocd

Once it is installed, you can check and make sure you have at least v 0.10.0 which support nRF52 chip

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$openocd -v
Open On-Chip Debugger 0.10.0
Licensed under GNU GPL v2
For bug reports, read
http://openocd.org/doc/doxygen/bugs.html

If you see any of these error messages:

  • openocd: error while loading shared libraries: libhidapi-hidraw.so.0: cannot open shared object file: No such file or directory

  • openocd: error while loading shared libraries: libusb-1.0.so.0: cannot open shared object file: No such file or directory

run the following command to install the libraries:

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$ sudo apt-get install libhidapi-dev:i386

Optional: Install Segger J-Link Drivers

If you wish to use the newt load or newt debug commands and a Segger J-Link, you will need to install the Segger J-Link drivers as well.

On Ubuntu systems, you will need to go to the Segger J-Link Downloads page and download an appropriate binary package:

  • For 32-bit systems download:
    J-Link Software and Documentation pack for Linux, DEB Installer, 32-bit
  • For 64-bit systems download: 
    J-Link Software and Documentation pack for Linux, DEB Installer, 64-bit

Once you have the file on your system, install the package via dpkg as follows (varying the file for the version of architecture you are using):

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$ sudo dpkg -i JLink_Linux_V618a_x86_64.deb
Selecting previously unselected package jlink.
(Reading database ... 175450 files and directories currently installed.)
Preparing to unpack JLink_Linux_V618a_x86_64.deb ...
Removing /opt/SEGGER/JLink ...
/opt/SEGGER/JLink not found (OK)
Unpacking jlink (6.18.1) ...
Setting up jlink (6.18.1) ...

Optional: Install minicom

Much of the interaction with your Mynewt device will happen over the serial port, including working with Shell-based commands on your device.

A relatively easy to use command line application to work with serial port connections is minicom, which is used throughout this learning guide. It can be installed from the command-line with the following command:

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$ sudo apt-get install minicom

You can establish a serial connection via minicom with the following command (adjusting the /dev/tty device name as appropriate):

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$ sudo minicom -D /dev/ttyUSB0

Native Installation (Win)

Mynewt relies on two command line utilities (newt and newtmgr), both of which are described elsewhere in this learning guide, as well as the presence of an ARM cross-compiling toolchain (arm-none-eabi-gcc, etc.).

Both of these need to be installed and available on your system to work with Mynewt projects.

Cut auto-reset trace

Windows serial has a somewhat annoying thing it does where it toggles the DTR/RTS lines when you open a serial port. This will make debugging impossible since you keep resetting the board. Before you continue you must cut the trace-jumper on the bottom of the board:

adafruit_products_cuttace.gif

Install newt & newtmgr Binaries

The official Mynewt documention for setting devices up on Windows is available here newt & newtmgr.

  • Firstly you need to install MSYS2/MinGW and Git, Our guide on Mingw and git installation may be useful!
  • Add a new user variable named MSYS2_PATH_TYPE and set the value to inherit in your Windows environment. This enables the MSYS2 and MinGW bash to inherit your Windows user Path values.
  • Add the MinGW bin path to your Windows Path. For example: if you install MSYS2/MinGW in the C:\msys64 directory, add C:\msys64\usr\bin to your Windows Path. Note: If you are using Windows 10 WSL, ensure that you use the C:\msys64\usr\bin\base.exe and not the Windows 10 WSL bash.
  • Download the latest newt & newtmgr binaries from http://www.apache.org/dyn/closer.lua/mynewt/ (click on suggested hosting mirrors), currently the latest version is apache-mynewt-1.5.0. You should now have both apache-mynewt-newt-bin-windows-1.5.0.tgz and apache-mynewt-newtmgr-bin-windows-1.5.0.tgz on your PC.
  • Extract them and copy newt.exe and newtmgr.exe to your C:\msys64\usr\binand you are good to
newt & newtmgr binaries are tested with Windows 7 and 10 on 64-bit platform. If you are using different (older) Windows version, please refer to mynewt guide to install it from source.
adafruit_products_newt_windows.png

You can test it by running newt and newtmgr from the shell

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$ newt version
Apache Newt version: 1.5.0

$ newtmgr version
Apache Newtmgr 1.5.0
adafruit_products_mgrtest.png

ARM Cross-Compiler

You will also need an cross-compiling toolchain for the ARM architecture, specifically GCC 4.9, since newt will call arm-none-eabi-gcc from the command line.

For details on installing this see the official Mynewt documentation here: https://mynewt.apache.org/latest/get_started/native_install/cross_tools.html

NOTE: arm-none-eabi-gcc also needs to be available in the system PATH variable to work with newt!

Apache Mynewt Tools

Standard Tools

There are two main tools used to interact with Mynewt devices:

  1. newt: Build system and project management tool
  2. newtmgr: Field management tool for deployed devices

Consult the dedicated tool pages for details on how to setup and use these two important tools.

Adafruit Tools

In addition to the default system tools, Adafruit maintains an iOS app called Adafruit Mynewt Manager that can be useful to monitor and work with deployed devices via your mobile phone.

adafruit_products_MynewtManager.png

newt

newt is a build and project management tool that hides most of the messy details of creating, building and debugging mynewt projects. With newt, you don't need to worry about makefiles, compiler flags, debug config settings, and library versions or updates. The details are elegantly hidden behind the easy to use 'newt' wrapper.

For full details on newt and the entire command set see the official newt documentation.

Installing newt

For details on installing the newt tool on your operating system of choice see:

Common newt Commands

Please consult the official newt documentation for details on every command, but the most commonly used commands are detailed below:

newt build

This command will build a firmware image for the specified target name, and will handle things like the makefile generation and any compiler parameters and file inclusions required by the target.

Full documentation: https://mynewt.apache.org/latest/newt/command_list/newt_build.html

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$ newt build first
Building target targets/first
...
Target successfully built: targets/first

newt create-image

This command assigns a version number to the image, and can also be used to optionally cryptographically sign images with an appropriate .pem key file.

Full documentation: https://mynewt.apache.org/latest/newt/command_list/newt_create_image.html

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$ newt create-image first 1.2.3
App image succesfully generated: [PATH]/bin/targets/first/app/apps/first/first.img

newt load <target_name>

This command will use a Segger J-Link (if you have one connected) to flash the version controlled .img file to the device.

Make sure you run 'newt create-image' on the firmware image before loading it to the device, or the firmware will be rejected by the bootloader which verifies all firmware at startup!

Full documentation: https://mynewt.apache.org/latest/newt/command_list/newt_load.html

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$ newt load first
Loading app image into slot 1

newt size

This command will give you detailed information on the flash and SRAM usage of your firmware, and can be helpful when debugging or when tight on space.

Full documentation: https://mynewt.apache.org/latest/newt/command_list/newt_size.html

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$ newt size first
Size of Application Image: app
  FLASH     RAM 
     59     246 *fill*
     32       0 apps_first.a
   1404     104 boot_bootutil.a
    426      26 boot_split.a
   1236       0 crypto_mbedtls.a
    492       0 encoding_base64.a
   1228       0 encoding_cborattr.a
   2912       0 encoding_tinycbor.a
    540     496 hw_bsp_ada_feather_nrf52.a
     64       0 hw_cmsis-core.a
    256       0 hw_drivers_uart_uart_hal.a
    392       0 hw_hal.a
   3744      72 hw_mcu_nordic_nrf52xxx.a
   7316    8233 kernel_os.a
   2856      44 libc_baselibc.a
   2416      24 mgmt_imgmgr.a
    220      20 mgmt_mgmt.a
    884     100 mgmt_newtmgr.a
   1401      44 mgmt_newtmgr_nmgr_os.a
    136      32 mgmt_newtmgr_transport_nmgr_shell.a
   1791      37 sys_config.a
   2203     100 sys_console_full.a
    544     128 sys_flash_map.a
   3171      90 sys_log_full.a
    408      12 sys_mfg.a
    752      76 sys_reboot.a
   5324     774 sys_shell.a
   1385      73 sys_stats_full.a
     32       5 sys_sysinit.a
   1676       0 time_datetime.a
    556       0 util_crc.a
    124       0 util_mem.a
    128       0 first-sysinit-app.a
   1492       0 libgcc.a

objsize
   text	   data	    bss	    dec	    hex	filename
  47568	    316	  10020	  57904	   e230	[PATH]/bin/targets/first/app/apps/first/first.elf

newt target show

This will give you a list of all targets defined in your project, and some basic details about them.

Full documentation: https://mynewt.apache.org/latest/newt/command_list/newt_target.html

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$ newt target show
targets/first
    app=apps/first
    [email protected]/hw/bsp/ada_feather_nrf52
    build_profile=debug
targets/my_blinky_sim
    app=apps/blinky
    [email protected]/hw/bsp/native
    build_profile=debug

newtmgr

newtmgr is an image management tool that can be used to interact with the bootloader and images on the device. For full details on the newtmgr tool and the entire command set see the official newtmgr documentation.

Installing newtmgr

For details on installing the newtmgr tool on your operating system of choice see:

Connection Profiles

The newtmgr tool works with connection profiles, such as serial or ble, depending on how you wish to communicate with the device under test.

Before you can use newtmgr you will need to setup at least one connection profile, as described below:

Adding a Serial Connection Profile

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$ newtmgr conn add serial1 type=serial connstring=/dev/tty.SLAB_USBtoUART

Or, on windows:

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$ newtmgr conn add serial1 type=serial connstring=COM14

Listing Existing Profiles

You can get a list of all defined connection profiles via:

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$ newtmgr conn show
Connection profiles: 
  serial1: type=serial, connstring='/dev/tty.SLAB_USBtoUART'

Test the Serial Connection Profile

You can test the connection profile with the 'image list' command, which will list any application images present in flash memory:

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$ newtmgr -c serial1 image list
Images:
 slot=0
    version: 0.1.0
    bootable: true
    flags: active confirmed
    hash: be52a255c25546dacc497d62faea910459903a1c1916ce831697d40fc2c20689
Split status: N/A (0)
The image shown above is the default image that the nRF52 Pro ships with

Common newtmgr Commands

The following commands are commonly used when doing day to day development and debugging with Mynewt based devices:

Display Scheduler Task Activity via 'taskstat'

You can also test the connection with newtmgr using the taskstat command, which will list some basic statistics about the tasks running in the task manager.

Enter the following command:

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$ newtmgr -c serial1 taskstat

Which should give you the following task statistics (output will vary depending on the Mynewt application that is running at the time):

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      task pri tid  runtime      csw    stksz   stkuse last_checkin next_checkin
    ble_ll   0   2       21     4381       80       58        0        0
   bleuart   5   3        0    12030      256       31        0        0
      idle 255   0    11980    16292       64       26        0        0
      main 127   1        0       27     1024      210        0        0

Uploading Application Images with newtmgr

If you don't have a Segger J-Link or similar debugger, the newtmgr tool can be used to upload an application image to the secondary bank of flash memory, and then switch application images during the next reset. This allows you to perform field updates over an inexpensive serial connection with no external HW required.

1. Build the Target Application (newt build)

The first step is of course to build the target application that you wish to deploy. The default bleuart project is used in this case:

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$ newt build bleuart
Building target targets/bleuart
...
Target successfully built: targets/bleuart

2. Sign and Version the Image (newt create-image)

You then need to 'sign' the image you just built with a version number and meta data used to validate the image when flashing, which is done via the create-image command:

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$ newt create-image bleuart 0.2.0
App image succesfully generated: [PATH]/bin/targets/bleuart/app/apps/bleuart/bleuart.img
Pay attention to the .img output filename since you will need this full path in the next step!

3. Upload the Image (newtmgr image upload)

Now that we have a signed and versioned firmware image, we can copy the image to bank 1 of flash memory using the serial bootloader and the newtmgr tool:

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$ newtmgr -c serial1 image upload [PATH]/bin/targets/bleuart/app/apps/bleuart/bleuart.img
353
704
...
157426
157612
Done

At this point, you can see that there are two images stored on the device in two different flash banks, the original 0.1.0 image that the board ships with, and the new 0.2.0 image we just built, signed and uploaded:

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$ newtmgr -c serial1 image list
Images:
 slot=0
    version: 0.1.0
    bootable: true
    flags: active confirmed
    hash: be52a255c25546dacc497d62faea910459903a1c1916ce831697d40fc2c20689
 slot=1
    version: 0.2.0
    bootable: true
    flags: 
    hash: 87276847693699896f68b3c26d378648cace2900db4145cd5ade6049ac5ec15a
Split status: N/A (0)
Pay attention to the 'flags' field, which indicates the state of images on the system. This value will change as we run through the update process.

4. Test the Image Upload (newtmgr image test [hash])

Now that the image has been uploaded successfully to the secondary bank of flash memory, we need to tell the system to 'test' the image during the next reset.

What the test command will do is check the signature of the image, and then try to switch the two flash banks so that the old application (0.1.0) is in the secondary flash bank, and the new application (0.2.0) is in the primary bank.

This happens at reset, and will cause a 15-20 second delay as the flash writes are happening, so be sure to wait for the testing process to complete before interacting or interferring with the device!

You can issue a test (and flash bank switch) request as follows, using the hash value from the image list command above:

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$ newtmgr -c serial1 image test 87276847693699896f68b3c26d378648cace2900db4145cd5ade6049ac5ec15a
Images:
 slot=0
    version: 0.1.0
    bootable: true
    flags: active confirmed
    hash: be52a255c25546dacc497d62faea910459903a1c1916ce831697d40fc2c20689
 slot=1
    version: 0.2.0
    bootable: true
    flags: pending
    hash: 87276847693699896f68b3c26d378648cace2900db4145cd5ade6049ac5ec15a
Split status: N/A (0)
Notice that the 0.2.0 image flag has been changed to PENDING, which means a test and flash bank switch is pending on the next reset!

5. Reset to Perform the Test and Image Bank Switch (newtmgr reset)

For the flash bank switch and test procedure to complete, you must reset the device, which can be done from the command line as follows:

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$ newtmgr -c serial1 reset
Done
Be sure to wait at least 20 seconds after issuing the reset command, since the flash write takes 15-20 seconds to complete and the device will appear unresponsive during the update process!

If you run the image list command again you will see that the banks and flags values have changed, with version 0.1.0 in the secondary bank and it's status set to 'confirmed':

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$ newtmgr -c serial1 image list
Images:
 slot=0
    version: 0.2.0
    bootable: true
    flags: active
    hash: 87276847693699896f68b3c26d378648cace2900db4145cd5ade6049ac5ec15a
 slot=1
    version: 0.1.0
    bootable: true
    flags: confirmed
    hash: be52a255c25546dacc497d62faea910459903a1c1916ce831697d40fc2c20689
Split status: N/A (0)

6. Confirm the Image Switch (newtmgr image confirm)

The final step is to 'confirm' the image update process to make it permanent, which is done via the image confirm sub-command:

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$ newtmgr -c serial1 image confirm
As of newtmgr 1.1.0 the 'confirm' command will always return "Error: 1", but the confirm process does work, as verified with the image list command below!

If you check the flags values again, you will see that version 0.2.0 is now 'confirmed' and will continue to execute every time you reset the device:

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$ newtmgr -c serial1 image list
Images:
 slot=0
    version: 0.2.0
    bootable: true
    flags: active confirmed
    hash: 87276847693699896f68b3c26d378648cace2900db4145cd5ade6049ac5ec15a
 slot=1
    version: 0.1.0
    bootable: true
    flags: 
    hash: be52a255c25546dacc497d62faea910459903a1c1916ce831697d40fc2c20689
Split status: N/A (0)
If you reset without confirming, the device will revert to the original (0.1.0) image!
Note: You can optionally skip the 'test + reset' phase, and go directly to confirming an image after the upload is finished by using 'newtmgr -c serial1 confirm [hash]' with the hash of the image to finalize. This is a more dangerous choice, but the option is there if you wish to save some time.

Display Internal Statistics

Mynewt has an internal statistics system that is very useful when debugging issues in the field or during development. You can defined individual statistics fields, and increment the values at appropriate moments, and access these from the command-line with the newtmgr stat command set.

List all Statistic Groups

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$ newtmgr -c serial1 stat list
stat groups:
    ble_att
    ble_gap
    ble_gattc
    ble_gatts
    ble_hs
    ble_l2cap
    ble_ll
    ble_ll_conn
    ble_phy
    ble_uart
    nffs_stats
    stat

List all Values in a Statistic Group

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$ newtmgr -c serial1 stat ble_phy
stat group: ble_phy
      8310 phy_isrs
         0 radio_state_errs
        15 rx_aborts
         0 rx_crc_err
         0 rx_hw_err
         0 rx_late
        15 rx_starts
         0 rx_valid
    265440 tx_bytes
         0 tx_fail
      8295 tx_good
         0 tx_hw_err
         0 tx_late

Apache Mynewt Applications

This section contains a guide on creating a progressively more complex application in Mynewt, starting with the absolute basics and adding useful features one by one.

The individual pages can be references in isolation, but the example code builds up from one example to the next in chronological order.

  • Create a New Project: This page shows how to generate a new project, and add a custom application and build target to the project.
  • Adding Tasks: Add a custom task to the task scheduler
  • Adding Shell Commands: Add a custom shell command to the serial-based console
  • Adding Statistics: Add custom statistics to track the internal state of the system in an easy to monitor fashion

Create a New Project

This page makes the following assumptions:

  1. You have already installed the newt and newtmgr tools on your system (see the Native Installation pages in this learning guide for details)
  2. The various build tools (arm-none-eabi-gcc, etc.) are available from the command-line
  3. You are using Mynewt version 1.1 for the tools and core codebase

This project will have the following features:

  • newtmgr support will be enabled over the serial port
  • Shell support will be included, allowing you to enter commands over the serial connection

Create a Project Skeleton

The first thing to do is create a project skeleton via the following command:

We'll use 'myproject' as a project name here, but you are free to change it to something else
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$ newt new myproject

This should give you the following output:

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Downloading project skeleton from apache/mynewt-blinky...
Installing skeleton in myproject...
Project myproject successfully created.

Download Project Dependencies

Next download the project dependencies from the associated repos.

Since this is a new project, only apache-mynewt-core will be downloaded:

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$ cd myproject
$ newt install -v

Depending on your system state, this should give you the following output:

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$ newt install -v
[apache-mynewt-core]:
Downloading repository description
Download successful!
Downloading repository mynewt-core (branch: master; commit: mynewt_1_1_0_tag) at https://github.com/apache/mynewt-core.git
Cloning into '/var/folders/86/hb2vp14n5_5_yvdz_z8w9x_c0000gn/T/newt-repo021712424'...
remote: Counting objects: 65349, done.
remote: Compressing objects: 100% (151/151), done.
remote: Total 65349 (delta 130), reused 162 (delta 95), pack-reused 65099
Receiving objects: 100% (65349/65349), 80.03 MiB | 1.94 MiB/s, done.
Resolving deltas: 100% (39656/39656), done.
Will create new branch mynewt_1_1_0_tag from tag tags/mynewt_1_1_0_tag
apache-mynewt-core successfully installed version 1.1.0-none

This should give you the following project structure:

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.
├── LICENSE
├── NOTICE
├── README.md
├── apps
│   └── blinky
│       ├── pkg.yml
│       └── src
├── project.state
├── project.yml
├── repos
│   └── apache-mynewt-core
└── targets
    ├── my_blinky_sim
    │   ├── pkg.yml
    │   └── target.yml
    └── unittest
        ├── pkg.yml
        └── target.yml

Create a New Application

Now that you have a project skeleton, you can start adding applications to it.

A Mynewt app requires at least a main() function, a pkg.yml file, and a most of the time a syscfg.yml file, as well as a new 'app' folder where the files should be stored.

To get started, create a new app folder as follows:

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$ mkdir apps/first
We'll call this application 'first', but you can use any name you find appropriate

Newt create the core apps/first/pkg.yml file with the following text (for example via $ nano apps/first/pkg.yml, or using your favorite text editor):

This file lists the external dependencies for your project
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pkg.name: apps/first
pkg.type: app

pkg.deps:
    - "@apache-mynewt-core/libc/baselibc"
    - "@apache-mynewt-core/kernel/os"
    - "@apache-mynewt-core/sys/sysinit"
    - "@apache-mynewt-core/sys/shell"
    - "@apache-mynewt-core/sys/console/full"
    - "@apache-mynewt-core/sys/log/full"
    - "@apache-mynewt-core/sys/stats/full"
    - "@apache-mynewt-core/hw/hal"
    - "@apache-mynewt-core/mgmt/imgmgr"
    - "@apache-mynewt-core/mgmt/newtmgr"
    - "@apache-mynewt-core/mgmt/newtmgr/transport/nmgr_shell"
    - "@apache-mynewt-core/boot/split"
    - "@apache-mynewt-core/boot/bootutil"

Next create a apps/first/syscfg.yml file with the following content (for example $ nano apps/first/syscfg.yml):

This file contains config settings for your application to control what features and used or enabled during the build process
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      syscfg.vals:
    # Use INFO log level to reduce code size.  DEBUG is too large for nRF51.
    LOG_LEVEL: 1
    REBOOT_LOG_CONSOLE: 1

    # Enable the shell task.
    SHELL_TASK: 1

    # Include names for statistics.
    STATS_NAMES: 1

    # Enable shell commands.
    STATS_CLI: 1
    LOG_CLI: 1
    CONFIG_CLI: 1

    # Enable newtmgr commands.
    STATS_NEWTMGR: 1
    LOG_NEWTMGR: 1
    CONFIG_NEWTMGR: 1

Finally create a apps/first/src/main.c file where the main source code will be stored:

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$ mkdir -p apps/first/src
$ nano apps/first/src/main.c

... and enter the following code:

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#include <assert.h>
#include <string.h>

#include "os/os.h"
#include "bsp/bsp.h"
#include "hal/hal_gpio.h"
#include "sysinit/sysinit.h"

int
main(int argc, char **argv)
{
    int rc;

    /* Initialize the OS */
    sysinit();

    /* Configure the LED GPIO as an output and HIGH (On) */
    hal_gpio_init_out(LED_BLINK_PIN, 1);

    while (1) {
        /* Run the event queue to process background events */
        os_eventq_run(os_eventq_dflt_get());
    }

    return rc;
}

Create a New Target

Next, you need to create a new target that points to your app via the following command:

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$ newt target create first
Target targets/first successfully created

... and then configure the new target with the following mandatory fields:

1. Set the Target's app Field

Point the new target to the app we created above via:

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$ newt target set first app=apps/first
Target targets/first successfully set target.app to apps/first

2. Set the Target's bsp Field

Next set the bsp (board support package) for the new target, which indicates the HW that the app will be running on.

If you are using the Adafruit nRF52 Pro Feather this should be:

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$ newt target set first [email protected]/hw/bsp/ada_feather_nrf52
Target targets/first successfully set target.bsp to @apache-mynewt-core/hw/bsp/ada_feather_nrf52

3. Set the build_profile Field

Finally set the build profile for the new target (debug or optimized):

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$ newt target set first build_profile=debug
Target targets/first successfully set target.build_profile to debug

4. Test the Target Settings

You can review the target settings via the following command:

'my_blinky_sim' is an artifact of the default project creation process and can be ignored
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$ newt target show first
targets/first
    app=apps/first
    [email protected]/hw/bsp/ada_feather_nrf52
    build_profile=debug
targets/my_blinky_sim
    app=apps/blinky
    [email protected]/hw/bsp/native
    build_profile=debug

Final Project Structure

The final project structure should look like this:

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apps/first
├── LICENSE
├── NOTICE
├── README.md
├── apps
│   └── blinky
│       ├── pkg.yml
│       └── src
│           └── main.c
├── pkg.yml
├── project.yml
├── src
│   └── main.c
└── syscfg.yml

Build and Flash the Target

Finally, you can build your target, pointing to the new application, and using the specified target BSP and build profile:

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$ newt build first
Building target targets/first
Compiling repos/apache-mynewt-core/boot/bootutil/src/loader.c
...
Compiling repos/apache-mynewt-core/util/mem/src/mem.c
...
Archiving util_mem.a
Linking [PATH]/bin/targets/first/app/apps/first/first.elf
Target successfully built: targets/first

Sign the Build with a Version Number

You can prepare the image to be flashed to the device with a mandatory version number and signing details via the newt create-image command:

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$ newt create-image first 0.1.5
App image succesfully generated: [PATH]/bin/targets/first/app/apps/first/first.img

And finally you can flash the image via one of two methods:

Flash the Image via a Segger J-Link

With the J-Link connected to the nRF52, run the following command to flash the signed image:

This command assumes that you have the Segger J-Link drivers installed on your system, as described in the Native Installation pages.
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$ newt load first
Loading app image into slot 1

Flash the Image via the Serial Port and newtmgr

For details on how to flash the image over newtmgr using only the serial port (no J-Link required), see Uploading Application Images with newtmgr.

Adding Tasks

The official Mynewt 'Task' documentation is available at: https://mynewt.apache.org/latest/os/core_os/task/task.html

A task (os_task) in Mynewt is made up of a task handler function, a task 'stack' which provide the block of memory that will be used when executing the task, and a priority level.

Since Mynewt is a multitasking environment, tasks are also assigned a priority level, and at any given time the highest priority task will run. When the highest priority task stops (waiting for an event, or when delayed in code) the next highest priority task will fire, and so on until the scheduler gets down to the lowest priority task, usually called 'idle' (which will be set by the kernel when the OS starts up).

Declaring a task, priority and stack size

In order to declare a task, you need to set the task's:

  • priority
  • stack size
  • and the name of the task handler that will be run when the task is active.

The task's priority can be from 1..255, where the higher the number the lower the priority.

The stack size is in units of os_stack_t, which is usually a 32-bit value, meaning a stack size of 64 (as shown in the example below) is 256 bytes wide.

The task handler has the following signature: void my_task_func(void *arg)

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/* Define task stack and task object */
#define MY_TASK_PRIO        (OS_TASK_PRI_HIGHEST)
#define MY_STACK_SIZE       OS_STACK_ALIGN(64)
struct os_task my_task;
os_stack_t my_task_stack[MY_STACK_SIZE];

Initializing a task

To initialize the task, you need to call the sysinit() function then add your task to the os via: os_task_init. This normally takes place in the main loop, or in a dedicated function called inside main like init_tasks().

os_task_init has the following signature and parameters:

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os_task_init(struct os_task *t, const char *name, os_task_func_t func,
        void *arg, uint8_t prio, os_time_t sanity_itvl,
        os_stack_t *stack_bottom, uint16_t stack_size)
  • struct os_task *t: A pointer to the os_task to initialize
  • const char *name: The public name to associate with this task, which will be visible in the shell, newtmgr, and other reporting systems.
  • os_task_funct_t func: The function to execute when this task is active, which will have the following signature: void my_task_handler(void *arg)
  • void *arg: Optional arguments to pass into the task handler
  • uint8_t prio: The priority level for the task, lower = higher priority
  • os_time_t sanity_itvl: The time at which this task should check in with the sanity task. OS_WAIT_FOREVER means never check in.
  • os_stack_t *stack_bottom: A pointer to the bottom of a task's stack.
  • uint16_t stack_size: The size of the task's stack (in os_stack_t units), which are usually 32-bits.

The following examples initialises a task matching the values declared earlier in this document:

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/* This is the main function for the project */
int main(void) {
    int rc;

    /* Initialize OS */
    os_init();

    /* Initialize the task */
    os_task_init(&my_task, "my_task", my_task_func, NULL, MY_TASK_PRIO,
                 OS_WAIT_FOREVER, my_task_stack, MY_STACK_SIZE);

    /* Start the OS */
    os_start();

    /* os start should never return. If it does, this should be an error */
    assert(0);

    return rc;
}

Implementing the task handler

The last part of the system is the task handler, which will be called every time that the task is active (as determined by the scheduler).

Task handlers are infinite loops that have an initial setup face, and then normally a while(1) loop that runs forever as long as the task is active.

The following example initialises a GPIO pin as an output, setting the pin high. It then starts an infinite loop and toggles the LED every second, sleeping between 1s intervals so that other tasks can run:

Note that there are two parts to the task handler. An initial chunk of code that will be run once when the task is initialized, then a 'while (1)' loop that will be run in repetition whenever the task has focus in the scheduler.
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static void
my_task_func(void *arg)
{
    hal_gpio_init_out(LED_BLINK_PIN, 1);

    while (1) {
        /* Wait one second */
        os_time_delay(OS_TICKS_PER_SEC * 1);

        /* Toggle the LED */
        hal_gpio_toggle(LED_BLINK_PIN);
    }
}

Task Delays

There are various ways that a task can be interrupted, such as delaying execution for a specific amount of time, waiting for an event on an event queue, waiting for a semaphore, etc.

Delaying your tasks is important, because as long as your task is active, no tasks of lower priority will execute. As such, it's important to manage your tasks as efficiently as possible to ensure that clock cycles are available for other tasks in the system.

os_time_delay

The os_time_delay function is the easiest way to cause a delay in execution in your task. Simply specify a specific number of ticks, and the scheduler will mark this task as inactive for the indicated delay.

Please note that os_time_delay uses system ticks, which may vary from one system to the next, so any delays should be based on the OS_TICKS_PER_SECOND macro to remain portable.

Example: Updating apps/first/src/main.c

A simple example of adding a blinky task handler to apps/first can be implemented by updating apps/first/src/main.c with the following code, and reflashing the firmware image:

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#include <assert.h>
#include <string.h>

#include "os/os.h"
#include "bsp/bsp.h"
#include "hal/hal_gpio.h"
#include "sysinit/sysinit.h"

/* Define task stack and task object */
#define LED_TASK_PRIO        (100)  /* 1 = highest, 255 = lowest */
#define LED_STACK_SIZE       OS_STACK_ALIGN(64)
struct os_task led_task;
os_stack_t led_task_stack[LED_STACK_SIZE];

static void led_task_func(void *arg);

int
main(int argc, char **argv)
{
    int rc;

    /* Initialize the task */
    os_task_init(&led_task, "blinky", led_task_func, NULL,
                 LED_TASK_PRIO, OS_WAIT_FOREVER, led_task_stack,
                 LED_STACK_SIZE);

    /* Initialize the OS */
    sysinit();

    while (1) {
        /* Run the event queue to process background events */
        os_eventq_run(os_eventq_dflt_get());
    }

    return rc;
}

static void
led_task_func(void *arg)
{
    /* Configure the LED GPIO as an output and HIGH (On) */
    hal_gpio_init_out(LED_BLINK_PIN, 1);

    while (1) {
        /* Wait one second */
        os_time_delay(OS_TICKS_PER_SEC * 1);

        /* Toggle the LED */
        hal_gpio_toggle(LED_BLINK_PIN);
    }
}
You can vary the blinky rate by adjusting the delay in 'os_time_delay' in the task handler

Checking Task Status

You can verify the task status from the command line with the newtmgr taskstat command:

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$ newtmgr -c serial1 taskstat
      task pri tid  runtime      csw    stksz   stkuse last_checkin next_checkin
    blinky 100   2        0        4       64       26        0        0
      idle 255   0      424        5       64       32        0        0
      main 127   1        0        3     1024       93        0        0

Adding Shell Commands

The official Shell documentation can be seen here: https://mynewt.apache.org/latest/os/modules/shell/shell.html

Mynewt includes a 'Shell' library that allows you to add an extensible command-line style interface to your applications. You can implement custom commands that users can execute over a simple serial connection, and display formatted text back to the end users.

Adding shell support

To add shell support to your app, make sure the following pkg.deps are defined in your pkg.yml file:

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pkg.deps:
    - "@apache-mynewt-core/sys/console/full"
    - "@apache-mynewt-core/sys/shell"
    - "@apache-mynewt-core/sys/sysinit"

And in the syscfg.vals section of syscfg.yml  add the following:

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syscfg.vals:
    # Enable the shell task.
    SHELL_TASK: 1

Adding a custom command handler

To add a new command handler use the following code snippets, placing the different sections at an appropriate place in your code:

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#include "console/console.h"
#include "shell/shell.h"

...

// Command handler prototype declaration
static int shell_test_cmd(int argc, char **argv);

// Shell command struct
static struct shell_cmd shell_test_cmd_struct = {
    .sc_cmd = "test",
    .sc_cmd_func = shell_test_cmd
};

...

// Implement your command handler
static int
shell_test_cmd(int argc, char **argv)
{
    console_printf("Test!\n");
    return 0;
}

...

// Call this before sysinit to register the command
#if MYNEWT_VAL(SHELL_TASK)
    shell_cmd_register(&shell_test_cmd_struct);
#endif

Example: Updating apps/first/src/main.c

You can update apps/first with a custom shell command using the following code in main.c:

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#include <assert.h>
#include <string.h>

#include "os/os.h"
#include "bsp/bsp.h"
#include "hal/hal_gpio.h"
#include "sysinit/sysinit.h"
#include "console/console.h"
#include "shell/shell.h"

/* Define task stack and task object */
#define LED_TASK_PRIO        (100)  /* 1 = highest, 255 = lowest */
#define LED_STACK_SIZE       OS_STACK_ALIGN(64)
struct os_task led_task;
os_stack_t led_task_stack[LED_STACK_SIZE];

/* LED task handler prototype declaration */
static void led_task_func(void *arg);

/* Command handler prototype declaration */
static int shell_test_cmd(int argc, char **argv);

/* Shell command struct */
static struct shell_cmd shell_test_cmd_struct = {
    .sc_cmd = "test",
    .sc_cmd_func = shell_test_cmd
};

int
main(int argc, char **argv)
{
    int rc;

    /* Initialize the task */
    os_task_init(&led_task, "blinky", led_task_func, NULL,
                 LED_TASK_PRIO, OS_WAIT_FOREVER, led_task_stack,
                 LED_STACK_SIZE);

    /* Call this before sysinit to register the command */
    #if MYNEWT_VAL(SHELL_TASK)
        shell_cmd_register(&shell_test_cmd_struct);
    #endif

    /* Initialize the OS */
    sysinit();

    while (1) {
        /* Run the event queue to process background events */
        os_eventq_run(os_eventq_dflt_get());
    }

    return rc;
}

/* Implement the 'test' command handler */
static int
shell_test_cmd(int argc, char **argv)
{
    console_printf("Test!\n");
    return 0;
}

static void
led_task_func(void *arg)
{
    /* Configure the LED GPIO as an output and HIGH (On) */
    hal_gpio_init_out(LED_BLINK_PIN, 1);

    while (1) {
        /* Wait one second */
        os_time_delay(OS_TICKS_PER_SEC * 1);

        /* Toggle the LED */
        hal_gpio_toggle(LED_BLINK_PIN);
    }
}

Testing the Shell Command

You can test the new 'test' shell command by connecting over serial:

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$ minicom -D /dev/tty.SLAB_USBtoUART

Once connected you can send the 'help' command to get a list of valid shell commands, and then then 'test' command which should display 'Test!' in the shell:

adafruit_products_Screen_Shot_2017-08-18_at_01.44.02.png

Adding Statistics

Full documentation on statistics is available here: https://mynewt.apache.org/latest/os/modules/stats/stats.html

Mynewt includes an internal statistics system where numeric values can be declared and incremented over time, then accessed as a debug and analysis tool.

For example, every time a specific sensor is accessed, you can increment the sensor_reads statistic value by one (assigning whatever variable name you want), and when a specific bug or condition occurs you can check the value to see whether or how many times the sensor was accessed before the specific condition occurs.

You can also use statistics to verify the number of bytes sent and received over a specific peripheral to make sure sensitive interrupt driven code is working well without having to stop the entire system.

Configuring Your App for Statistics

To enable statistics in your application, the following dependency needs to be present in pkg.yml:

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pkg.deps:
    - "@apache-mynewt-core/sys/stats"

To save flash space internally, statistics are referenced by number by default. If you wish to preserve the full name of the individual statistics for easier debugging, then the following flag also needs to be added to the syscfg.yml file:

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syscfg.vals:
    # Include names for statistics.
    STATS_NAMES: 1

Optionally, if you wish to access statistics from the shell interface, you can also enable the 'stat' command with the following flag in syscfg.yml:

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syscfg.vals:
    STATS_CLI: 1

Adding Stats to your main.c File:

Stats requires the following header be present:

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#include <stats/stats.h>

This will enable the use of the STATS* macros to define the stats layout, following the example below:

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STATS_SECT_START(my_stat_section)
    STATS_SECT_ENTRY(attempt_stat)
    STATS_SECT_ENTRY(error_stat)
STATS_SECT_END

At compile time, this will resolve to the following structure:

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struct stats_my_stat_section {
    struct stats_hdr s_hdr;
    uint32_t sattempt_stat;
    uint32_t serror_stat;
};

You will also need to provide names for each field, regardless of WHETHER you have enabled naming support via STATS_NAMES or not:

Note that the field names need to match between the STATS_SECT_ENTRY name above and the STATS_NAME entry below!
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/* Define a few stats for querying */
STATS_NAME_START(my_stat_section)
    STATS_NAME(my_stat_section, attempt_stat)
    STATS_NAME(my_stat_section, error_stat)
STATS_NAME_END(my_stat_section)

At compile time, this will resolve to the following structure:

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struct stats_name_map g_stats_map_my_stat_section[] = {
    { __builtin_offsetof (struct stats_my_stat_section, sattempt_stat), "attempt_stat" },
    { __builtin_offsetof (struct stats_my_stat_section, serror_stat), "error_stat" },
};

Accessing the Stats in Your Code

You will need to declare a global variable somewhere to holds the stats data, using the model below:

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STATS_SECT_DECL(my_stat_section) g_mystat;

If the global definition is is another file and you are referencing it elsewhere, you would declare this in the file where you will modify locally:

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extern STATS_SECT_DECL(my_stat_section) g_mystat;

Initializing the Stats

Before your stats can be used or accessed, they need to be initialised and registered.

You can initialise your stats entry as follows:

The stats_init() and stats_register() function calls should occur AFTER the sysinit(); function!
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rc = stats_init(
    STATS_HDR(g_mystat),
    STATS_SIZE_INIT_PARMS(g_mystat, STATS_SIZE_32),
    STATS_NAME_INIT_PARMS(my_stat_section));
assert(rc == 0);

For the stat size, you can use one of the following values:

  • STATS_SIZE_16 -- stats are 16 bits (wraps at 65536)
  • STATS_SIZE_32 -- stats are 32 bits (wraps at 4294967296)
  • STATS_SIZE_64 -- stats are 64-bits

You then need to register the stats entry so that you can access it, which is done via the following function call:

NOTE: The name below is the name that you will use when accessing the stats via the console or via the newtmgr stat command
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rc = stats_register("my_stats", STATS_HDR(g_mystat));
assert(rc == 0);

Updating the Stats Values

Incrementing

To increment the stats values, you can use the STATS_INC or STATS_INCN macros, as shown below:

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STATS_INC(g_mystat, attempt_stat);
rc = do_task();
if(rc == ERR) {
    STATS_INC(g_mystat, error_stat);        
}

To increment the value a specific number use STATIS_INCN:

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STATS_INCN(g_mystat, attempt_stat, 5);

Accessing Stats with the Console or newtmgr

Console Access

Assuming that you have enabled named access to stats via STATS_NAME_ENABLE you can access your stats from the console via:

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stat my_stats

This will give you something resembling the following output:

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12274:attempt_stat: 3
12275:error_stat: 0

If you don't have names enabled via STATS_NAME_ENABLE you would see something like this:

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stat my_stats
29149:s0: 3
29150:s1: 0

newtmgr Access

You can also access stats through newtmgr as follows:

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$ newtmgr -c serial1 stat my_stats
Return Code = 0
Stats Name: my_stats
  attempt_stat: 0
  error_stat: 0

Example: Adding Stats to apps/first/src/main.c

You can extend apps/first with custom stats by updating apps/first/src/main.c with the following code:

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#include <assert.h>
#include <string.h>

#include "os/os.h"
#include "bsp/bsp.h"
#include "hal/hal_gpio.h"
#include "sysinit/sysinit.h"
#include "console/console.h"
#include "shell/shell.h"
#include "stats/stats.h"

/* Define task stack and task object */
#define LED_TASK_PRIO        (100)  /* 1 = highest, 255 = lowest */
#define LED_STACK_SIZE       OS_STACK_ALIGN(64)
struct os_task led_task;
os_stack_t led_task_stack[LED_STACK_SIZE];

/* LED task handler prototype declaration */
static void led_task_func(void *arg);

/* Command handler prototype declaration */
static int shell_test_cmd(int argc, char **argv);

/* Shell command struct */
static struct shell_cmd shell_test_cmd_struct = {
    .sc_cmd = "test",
    .sc_cmd_func = shell_test_cmd
};

/* Define a custom stats group for querying */
STATS_SECT_START(led_stat_section)
    STATS_SECT_ENTRY(led_toggles)
STATS_SECT_END

/* Define a few stat name fields for querying */
STATS_NAME_START(led_stat_section)
    STATS_NAME(led_stat_section, led_toggles)
STATS_NAME_END(led_stat_section)

/* Add the global variable to access and increment stats */
STATS_SECT_DECL(led_stat_section) g_ledstats;

int
main(int argc, char **argv)
{
    int rc;

    /* Initialize the task */
    os_task_init(&led_task, "blinky", led_task_func, NULL,
                 LED_TASK_PRIO, OS_WAIT_FOREVER, led_task_stack,
                 LED_STACK_SIZE);

    /* Call this before sysinit to register the command */
    #if MYNEWT_VAL(SHELL_TASK)
        shell_cmd_register(&shell_test_cmd_struct);
    #endif

    /* Initialize the OS */
    sysinit();

    /* Initialise the custom stats section */
    rc = stats_init(
        STATS_HDR(g_ledstats),
        STATS_SIZE_INIT_PARMS(g_ledstats, STATS_SIZE_32),
        STATS_NAME_INIT_PARMS(led_stat_section));
    assert(rc == 0);

    /* Then register the custom section with the stats system */
    rc = stats_register("led_stats", STATS_HDR(g_ledstats));
    assert(rc == 0);

    while (1) {
        /* Run the event queue to process background events */
        os_eventq_run(os_eventq_dflt_get());
    }

    return rc;
}

/* Implement the 'test' command handler */
static int
shell_test_cmd(int argc, char **argv)
{
    console_printf("Test!\n");
    return 0;
}

static void
led_task_func(void *arg)
{
    /* Configure the LED GPIO as an output and HIGH (On) */
    hal_gpio_init_out(LED_BLINK_PIN, 1);

    while (1) {
        /* Wait one second */
        os_time_delay(OS_TICKS_PER_SEC * 1);

        /* Toggle the LED */
        hal_gpio_toggle(LED_BLINK_PIN);

        /* Increment the LED stat */
        STATS_INC(g_ledstats, led_toggles);
    }
}

Monitoring via netwmgr

You can monitor the led_toggles value via newtmgr with the following command (where we can see that the LED had been toggled 11 times to far in this case):

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$ newtmgr -c serial1 stat led_stats
stat group: led_stats
        11 led_toggles

Monitoring via shell/console

Alternatively, you can connect to the shell (for example, via: $ minicom -D /dev/tty.USBtoUART) and run the stat led_stats command to get the same value(s):

adafruit_products_Screen_Shot_2017-08-18_at_10.49.15.png

Adding BLE UART Support

The easiest way to add BLE UART support is using the bleuart helper module that is part of Adafruit_Mynewt, an in house Mynewt project that we created during product development.

If you wish to test a complete application that shows how to use BLE UART, you should start with the bleuart example application, which exposes shell commands to work with BLE UART, as well as tracks the TX and RX byte count via statistics, and works well with the Adafruit Mynewt Manager mobile application.

This section will be expanded in the near future with details on working with BLE and BLE UART in Mynewt, but at the moment we only have example code that we've written to get you started.

Mynewt Nimble (BLE Stack) Documentation

Mynewt's open source Bluetooth Low Energy stack is called nimble. Full documentation on number can be found via the link below:

Advanced Debugging

The pages in this section are for advanced users who need to debug remote or complex systems, and are aimed at giving you a head start solving specific problems:

  • GDB Debugging: General overview of common GDB debugging commands and suggestions on how to debug common problems via GDB
  • Command Line Debugging: Some common tricks to help debug issues from the command line
  • Field Debugging Tips: Advice on debugging crash dumps from devices in the field

GDB Debugging

GDB debugging will require a Segger JLink for the GDB Server and debug port access

The definitive guide to GDB is available here:
ftp://ftp.gnu.org/old-gnu/Manuals/gdb/html_chapter/gdb_toc.html

Starting the Debugger

You can start GDB (GNU Debugger) with newt with the following command, with a
JLink connected to the target device:

# Optionally build and flash the image
$ newt build target_name
$ newt create-image target_name 0.0.0
$ newt load target_name

# Start GDB
$ newt debug target_name

You can then start and stop code execution on the target MCU via:

(gbd) monitor halt

and

(gbd) monitor go

You can also start a fresh run of the code via:

(gbd) monitor reset
(gdb) c

You can check if the OS is running by executing the following code, which
will display the OS time counter:

(gdb) p/d g_os_time

Displaying Values

To display the current state of a struct or global variable, use the print
[name] (or p [name]) command.

Basic Example

The example below halts the processor and then prints a struct instance named
ble_phy_stats.

> Tip: You can optionally enable pretty printing via set print pretty on

(gdb) monitor halt
(gdb) set print pretty on
(gdb) print ble_phy_stats
$5 = {
  s_hdr = {
    s_name = 0x0,
    s_size = 0 '\000',
    s_cnt = 0 '\000',
    s_pad1 = 0,
    s_next = {
      stqe_next = 0x0
    }
  },
  sphy_isrs = 0,
  stx_good = 1,
  stx_fail = 0,
  stx_late = 0,
  stx_bytes = 27,
  srx_starts = 0,
  srx_aborts = 0,
  srx_valid = 0,
  srx_crc_err = 0,
  srx_late = 0,
  sno_bufs = 0,
  sradio_state_errs = 0,
  srx_hw_err = 0,
  stx_hw_err = 0
}

Formatting Display Values

You can also format the printed values with the following formatters:

  • x Regard as integer and display as hexadecimal
  • d Regard as integer and display as signed decimal
  • u Regard as integer and display as unsigned decimal
  • c Regard as integer and print as a char constant
  • f Regard as float and print in floating point syntax
  • t Print integer as binary
  • a Print as an address (hex plus offset). Useful to discover where an address is located (ex. p/a 0x12345 yields $3 = 0x12345 &lt;_initialize_vx+396&gt;)

To print the BLE link layer stack (g_ble_ll_stack) in hex enter:

(gdb) p/x g_ble_ll_stack
$17 = {0xdeadbeef <repeats 22="" times="">, 0x20002568, 0x304, 0xe000e100, 0x100, 0x20001be4, 0x0, 0xffffffff, 0x0,
  0xffffffff, 0x20002204, 0x19f14, 0x20002218, 0x0, 0x20001e90, 0x10000000, 0x20002180, 0x354, 0xa0a3, 0x92b2,
  0x61000000, 0x20001e8c, 0x200021d8, 0x0, 0x9657, 0x4, 0xffffffff, 0xffffffff, 0x1fff8000, 0x0, 0xa897, 0x0, 0xa85d,
  0x1fff8000, 0xffffffff, 0xffffffff, 0x1fff8000, 0x0, 0x0, 0x8, 0xde, 0x93c9, 0x0}

Displaying an Array of Values

You can display the contents of an array as follows:

(gdb) monitor halt
(gdb) set print pretty on
(gdb) print *[email protected]

Useful Mynewt/Nimble Structs and Fields

Some useful Mynewt or nimble fields to display can be seen below:

  • ble_phy_stats - PHY stats for traffic tracking
  • ble_ll_stats - Link layer stats
  • ble_ll_conn_stats - Connection stats
  • g_ble_ll_adv_sm - Advertising state machine
  • g_ble_ll_stack - Link layer stack

For example:

(gdb) monitor halt
(gdb) set print pretty on
(gdb) p ble_phy_stats
$16 = {
  s_hdr = {
    s_name = 0x0,
    s_size = 0 '\000',
    s_cnt = 0 '\000',
    s_pad1 = 0,
    s_next = {
      stqe_next = 0x0
    }
  },
  sphy_isrs = 0,
  stx_good = 1,
  stx_fail = 0,
  stx_late = 0,
  stx_bytes = 27,
  srx_starts = 0,
  srx_aborts = 0,
  srx_valid = 0,
  srx_crc_err = 0,
  srx_late = 0,
  sno_bufs = 0,
  sradio_state_errs = 0,
  srx_hw_err = 0,
  stx_hw_err = 0
}

Memory Manipulation

You can display the memory contents of a specific address via the x command.

To see the main stack pointer location on an ARM chip, for example, run:

(gdb) x 0
0x0:    0x20008000

You can also adjust the output size with the optional x/nfu flags:

  • n Indicates how much memory to display (in u units), default = 1
  • f Indicates the display format, where:
    • s means null-terminated string
    • i means machine instruction
    • x Display as hexadecimal (default)
    • d Display as signed decimal
    • u Display as unsigned decimal
    • c Print as a char constant
    • f Print in floating point syntax
    • t Print integer as binary
  • u The unit size, which can be:
    • b Bytes
    • h Halfwords (two bytes)
    • w Words (four bytes)
    • g Giant worlds (eight bytes)

> Note: Whenever you change the unit size (u), the updated value becomes
> the system default and will be retained on future requests until it is
> changed again.

For example, to display the same 32-bit stack pointer at address 0 on an ARM
processor as four individual bytes displayed as unsigned decimal values you
would enter:

(gdb) x/4ub 0
0x0:    0   128 0   32

To display the 32-bit value in binary notation you would enter:

(gdb) x/4tb 0
0x0:    00000000    10000000    00000000    00100000

To display 4 'words' as 32-bit values in hex notation:

(gdb) x/4xw 0
0x0:    0x20008000  0x00003049  0x00003099  0x00003099

Stack Manipulation

The following commands can be used to work with the stack such as producing a
dump of the stack frames, or checking for stack overflow.

Display the Stack Trace

You can display a list of function calls up to the point where the MCU halted
with the backtrace or bt command, which will dump individual stack
frame records:

(gdb) bt
#0  os_tick_idle (ticks=131072) at hal_os_tick.c:146
#1  0x000091f6 in os_idle_task (arg=<optimized out="">) at os.c:64
#2  0x00000000 in ?? ()

Each line shows the frame number, and the function name and return address.
In this case, the code has stopped at os_tick_idle in halostick.c, which
was called from os_idle_task in os.c.

Display Stack Frame Details

You can display detailed information about a specific stack frame via the
info frame [n] command:

(gdb) info frame
Stack level 0, frame at 0x20001e60:
 pc = 0x184aa in os_tick_idle (hal_os_tick.c:146); saved pc = 0x91f6
 called by frame at 0x20001e80
 source language c.
 Arglist at 0x20001e40, args: ticks=131072
 Locals at 0x20001e40, Previous frame's sp is 0x20001e60
 Saved registers:
  r3 at 0x20001e48, r4 at 0x20001e4c, r5 at 0x20001e50, r6 at 0x20001e54, r7 at 0x20001e58, r8 at 0x20001e40,
  r9 at 0x20001e44, lr at 0x20001e5c

To display the arguments for the current stack frame you can run:

(gdb) info args
ticks = 131072

To display the local variables (one per line) for the stack frame run (data
may or may not be available depending on build setings):

(gdb) info locals
ocmp = <optimized out="">

Displaying ARM Registers

You can also display a list of the ARM registers via info registers.

The following example shows the same pc value seen above where we are halted
at 0x184aa on os_tick_idle, and the stack pointer (sp) is at 0x20001e40,
one 32 byte (0x20) stack frame away from the value seen earlier.

(gdb) info registers
r0             0x800000 8388608
r1             0x4000b000   1073786880
r2             0xb4a5e0 11838944
r3             0x3fffef 4194287
r4             0xffffffff   4294967295
r5             0xffffff 16777215
r6             0x504    1284
r7             0x540    1344
r8             0xff800000   4286578688
r9             0x20000  131072
r10            0x1fff8000   536838144
r11            0x0  0
r12            0x20 32
sp             0x20001e40   0x20001e40 <g_idle_task_stack+192>
lr             0x18435  99381
pc             0x184aa  0x184aa <os_tick_idle+182>
xpsr           0x21000000   553648128
MSP            0x20008000   536903680
PSP            0x20001e40   536878656
PRIMASK        0x1  1
BASEPRI        0x0  0
FAULTMASK      0x0  0
CONTROL        0x2  2

Working with Source Code

You can display source code inside GDB with some basic commands.

Displaying a function

This will display the first 10 lines of the specified function:

(gdb) list os_idle_task
39  #endif
40  #define MAX_IDLE_TICKS  (600 * OS_TICKS_PER_SEC)        /* 10 minutes */
41
42  void
43  os_idle_task(void *arg)
44  {
45      os_sr_t sr;
46      os_time_t now;
47      os_time_t iticks, sticks, cticks;
48

To display the next 10 lines enter:

(gdb) list
49      /* For now, idle task simply increments a counter to show it is running. */
50      while (1) {
51          ++g_os_idle_ctr;
52          OS_ENTER_CRITICAL(sr);
53          now = os_time_get();
54          sticks = os_sched_wakeup_ticks(now);
55          cticks = os_callout_wakeup_ticks(now);
56          iticks = min(sticks, cticks);
57          if (iticks &lt; MIN_IDLE_TICKS) {
58              iticks = 0;

> Tip: You can adjust the number of lines displayed via set listsize [count]

Displaying code at a specific address

If you wish to display the code at a specific address you can prefix the address
with a * character as shown below:

(gdb) list *0x00009e54
0x9e54 is in crash_device (crash_test.c:46).
41      if (!strcmp(how, "div0")) {
42
43          val1 = 42;
44          val2 = 0;
45
46          val3 = val1 / val2;
47          console_printf("42/0 = %d\n", val3);
48      } else if (!strcmp(how, "jump0")) {
49          ((void (*)(void))0)();
50      } else if (!strcmp(how, "ref0")) {

Running an arbitrary function when halted at a breakpoint

When halted at a breakpoint, you can run a function via the call command. Tip via Håkon Alseth.

> Make sure to include the parenthesis after the function name when issuing the call command, which will cause the device to go back to the halt state once the function has completed execution.

Connect to the target using $ newt debug target_name or via some variation of the following code:

arm-none-eabi-gdb _build/*.out 
(gdb) target remote :2331 
(gdb) load

Then run until you hit the BP, and at an appropriate moment execute the call command with your target function name:

(gdb) mon reset 
(gdb) c 
<break somewhere="" in="" your="" code,="" optionally="" using="" ctrl+c=""> 
(gdb) call test_function()

Command Line Debugging

The following tips and tricks can be used when debugging from the command line.

Grep'ing Source Code

The grep tool allows you to efficiently find references to strings in the
current folder or recursively, such as looking for every reference to a
specific function name or variable in your codebase.

Grep recursively for a partial string

To perform a recursive search for a partial string enter:

$ grep -rn "./" -e "SEARCH_PATTERN"
  • r means recursive
  • n means show line numbers
  • e is the string to search for (SEARCH_PATTERN in this case)

This will return a reference to any instance starting with SEARCH_PATTERN,
including the specific line number.

> NOTE: This search is case-sensitive. Adding the i flag will make
the search case insensitive.

Grep recursively for an exact string

To perform a recursive search for an exact match of an entire string enter:

$ grep -rnw "./" -e "SEARCH_PATTERN"
  • w means whole word

This will return a reference to any instances of SEARCH_PATTERN.

Grep recursively for a string ignoring the case

If you wish the search to be case insensitive you can also add the -i
argument, as shown below:

$ grep -rni "./" -e "SeArCh_PaTtErN"
  • i means case insensitive (default is case sensitive searching)

This would return 'SearchPattern' or 'SEARCHPATTERN' as valid matches.

Grep recursively with specific file types

If you wish to restrict your search to a specific file type, you can use the
--include flag as follows:

$ grep --include=\*.{c,h} -rnw "./" -e "SEARCH_PATTERN"

This will only search files ending in .c or .h

You can also exclude certain file types with the --exclude flag:

$ grep --exclude=*.o -rnw "./" -e "SEARCH_PATTERN"

This will exclude all files ending in .o from the search.

Field Debugging Tips

Debugging devices deployed remotely is always a challenge but this documentation gives some basic techniques to help debug issues remotely.

Debugging Crash Dumps

If a task crashes (enter the fault_handler etc.) it will normally generate a simple dump of the system registers, which can be useful to find the cause of the problem if you have the matching .elf file locally.

This example uses the crash_test library from apache-mynewt-core to simulate various crash events locally via the crash command from shell:

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crash div0
6976:Unhandled interrupt (3), exception sp 0x2000a960
6976: r0:0x00000000  r1:0x000242bd  r2:0x00000000  r3:0x0000002a
6976: r4:0x00000000  r5:0x2000c002  r6:0x2000bffc  r7:0x00025e34
6976: r8:0x0000d04d  r9:0x0000000c r10:0x20009068 r11:0x55555556
6976:r12:0x00000000  lr:0x00009e45  pc:0x00009e54 psr:0x61000000
6976:ICSR:0x00419803 HFSR:0x40000000 CFSR:0x02000000
6976:BFAR:0xe000ed38 MMFAR:0xe000ed34

In the example above we see the output of a divide by zero crash.

The important register value is pc. Make a note of this address since your will use it in one of the debugging methods described below:

Option 1: Debugging Crash Dumps with GDB

If you have access to the matching app revision, build the target and deploy it to the device under test:

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$ newt build throughput
$ newt create-image throughput 0.1.0
$ newt load throughput

To start GDB via the following command:

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$ newt debug throughput
Please note that you will require a Segger J-Link to run the 'newt debug' command!

This will start up the GDB server and connect to the device under test.

See GDB Debugging for details on using GDB.

Run the following commands from the GDB shell:

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(gdb) monitor go
(gdb) list *0x00009e54
0x9e54 is in crash_device (crash_test.c:46).
41	    if (!strcmp(how, "div0")) {
42
43	        val1 = 42;
44	        val2 = 0;
45
46	        val3 = val1 / val2;
47	        console_printf("42/0 = %d\n", val3);
48	    } else if (!strcmp(how, "jump0")) {
49	        ((void (*)(void))0)();
50	    } else if (!strcmp(how, "ref0")) {

You can see here that line 46 of crash_test.c caused the fault, which is where the divide by zero error occurs.

Option 2: Debugging Crash Dumps with objdump

If you have the .elf file but can't use GDB debugger you can see the code for the specified address from the command line using the objdump tool that is part of GCC.

From the command-line (with GCC available as part of the system path) run the following command:

Note: You must specify a --stop-address that is higher than the --start-address with this command, but you can increment the hex value by 1 byte to return only the line of code that caused the crash. You can play with the start and stop addresses to provide some context to the error.

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$ arm-none-eabi-objdump -S --start-address=0x00009e54 --stop-address=0x00009e55 bin/targets/throughput/app/apps/throughput/throughput.elf

bin/targets/throughput/app/apps/throughput/throughput.elf:     file format elf32-littlearm


Disassembly of section .text:

00009e54 <crash_device+0x1c>:
    if (!strcmp(how, "div0")) {

        val1 = 42;
        val2 = 0;

        val3 = val1 / val2;
    9e54:	fb93 f3f2 	sdiv	r3, r3, r2

Debugging Repeatable Crashes

If you can repeat the crash scenario, you can find out the cause with the following sequence of events and two terminal windows:

Run GDB with the following command:

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$ newt run <target-name> 0

When GDB comes up type c and press enter.

In a different shell, proceed to do whatever is required to cause the device to crash (such as sending a shell command, newtmgr cmd, etc..

If the device crashes, GDB should indicate such. You can then type the following commands in GDB to find out where is crashed:

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(gdb) bt
(gdb) p *g_current_task

Adafruit_Mynewt

Adafruit_Mynewt is a sample Mynewt project that we use internally for various projects and experiments.

It isn't necessary to use this with the Adafruit Feather nRF52 Pro, but the repository contains a number of helper modules and apps, and can help you get started working with things like BLE UART and general Bluetooth Low Energy communication.

Installing Adafruit_Mynewt

To install and use the repo locally, first create a git clone of it using your favorite git IDE or from the command-line via:

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$ git clone [email protected]:adafruit/Adafruit_Mynewt.git

Once the repository in installed locally, enter the Adafruit_Mynewt directory and install the Mynewt dependencies and libraries via:

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$ newt install -v
NOTE: You only need to run this command once, since the mynewt core libraries are not part of the Adafruit_Mynewt repo itself and will be downloaded into the '/repos' folder by 'newt install'

Provided Apps

Not all of the apps includes in the /apps folder are useful to everyone, but the following may serve as a good starting point for you own applications of learning requirements:

  • bleuart: This example initialises the BLE stack, and includes a BLE UART service and shell commands and statistics support to interact with the BLE UART service. This is the application that ships with our boards off the assembly line.
  • throughput: This example can be used to test the throughput speed of BLE using BLE UART. It includes a shell command ('nustest') to start and configure the throughput tests.

Helper Modules

The following modules are defined as part of Adafruit_Mynewt to make certain tasks easier to implement:

  • adautil: This module includes a number of helpers to facilitate working with UUIDs, config settings, data logs, timer timeouts, etc.
  • bledis: This module facilitates working with the Device Information Service (dis)
  • bleuart: This module facilitates working with the Nordic UART Service (nus AKA 'BLE UART')
  • fifo: This module provides a First In First Out (FIFO) buffer implementation that plays well with the internal scheduler and RTOS architecture

External Content

The following external content may be useful understanding some of the many features available in Apache Mynewt:

Mynewt Bootloader

Build and Package Management

Downloads

The following resources may be useful working with the Bluefruit nRF52 Feather:

MyNewt Bootloader

This is if you want to program in MyNewt support - the bootloader will not work with Arduino!

You can use adalink and a jlink to program this in via SWD to address 0 with something like:

adalink -v nrf52832 -p jlink -b feather52_boot_bleuart.bin 0

(Don't forget you may have to erase the chip)

Module Details

The Bluefruit nRF52 Feather uses the MDBT42Q module from Raytac. Details on the module, including FCC and other certifications are available in the document below:

Schematic

microcontrollers_revgsch.png

Schematic (pre March 16 2018)

microcontrollers_BluefruitnRF52Feather_Rev-F.png

This guide was first published on Aug 18, 2017. It was last updated on Aug 18, 2017.