The WICED Feather uses the same standard pinout as the rest of the Feather family, allowing you to use the same Feather Wings across all your compatible devices.
It has the standard Feather on board LIPO battery charger (simply connect a LIPO battery and USB power at the same time), and 3.3V voltage regulation from either USB or VBAT (the LIPO cell) with automatic switching between power supplies.
The pins on the WICED Feather can be configured for several different purposes, with the main config options shown in the illustration below:
For most pin names, you must append 'P' to the pin name shown on the silk screen. The table below lists the pin names on the silkscreen and their corresponding macro in your Arduino code:
WAKE or PA0
Other notable pins defined in feather.h include:
Main Macro Name
Direct Arduino Pin Name
For further details on the board layout, see the schematic here.
The WICED Feather can be run from either 5V USB power or a standard ~3.7V LIPO cell, and includes the ability to charge LIPO cells from USB power when both are connected at the same time.
The following pins are included as part of the WICED Feather's power system:
- 3V: The output of the on-board 3.3V 600mA voltage regulator
- RTC: The input for the realt-time clock (RTC) on the STM32F205 (optional)
- GND: The common/GND pin which should be connect to GND on any other boards you use
- BAT: The input for the 3.7V LIPO cell
- EN: The 'EN' switch for the 3.3V voltage regulator. Set this to GND to disable power.
- VUSB: The 5V USB power input (USB VBUS)
- A1: This pin is optionally connected to a 10K+10K voltage divider that allows you to safely measure the output of the LIPO cell using the internal ADC (analog to digital converter).
LIPO Cell Power Monitoring (A1)
The LIPO battery level can optionally be monitored via a voltage divider configured on ADC pin A1.
To enable the 10K + 10K voltage divider (which will divide the LIPO voltage levels in half so that the ADC pin can safely read them), you need to solder shut the BATADC solder jumper on the bottom of the PCB:
This will allow you to read the voltage level of the LIPO cell using pin A1 where each value on the ADC is equal to 0.80566mV since:
- 3300mV / 4096 (12-bit ADC) = 0.80566406mV per LSB
You need to double the calculated voltage to compensate for the 10K+10K voltage divider, so in reality every value from the ADC is equal to 1.61133mV on the LIPO cell, although it appears on the ADC at half that level.
The WICED Feather contains an optional (default = off) 16MBit SPI flash chip that is controlled by FeatherLib.
In order to keep the maximum number of pins available to customers, the SPI flash is disabled by default, but can be enabled with USB Mass Storage support so that you can access the contents on the flash memory from your PC to easily exchange data and files. Simply solder the SPIFCS solder jumper on the bottom of the device closed, and make sure you are running FeatherLib version 0.6.0 or higher to enabled flash and USB mass storage support.
SPI flash is disabled by default. It can be enabled by soldering the SPIFCS (A4) solder jumper on the back of the PCB closed before powering the board up, which will connect the CS/SSEL of the SPI flash to pin A4:
Pins that can be used as PWM outputs are marked with a tilde character ('~') on the silk screen.
The timers associated with specific PWM outputs are listed below. These timers are important since all PWM outputs on the same HW timer will use the same period or pulse width. This means that if you set the pulse width for PA1, which uses HW Timer 5, this will also set the pulse width for PA2 and PA3 which use the same timer peripheral block.