# Wearable Continuous Temperature Monitor with Adafruit IO
## Overview
## Wearable Continuous Temperature Monitor
This armband **continuously monitors body temperature while you sleep.** You can monitor temperature **hands-free** from another device, even if you're in a different room.
You can monitor temperature for **up to 8 hours on a full charge** (tested on a 3.3V 400mAh lipoly battery, data sent to Adafruit IO once every minute). **Data is sent to your Adafruit IO account for long-term storage and visualization**. Use Adafruit IO Triggers to be **notified by email when the temperature increases past a set threshold**.
## Bluetooth Low Energy (BLE) Temperature Armband
Monitor your (or someone else's) temperature, hands-free, from anywhere with the Adafruit Feather nRF52840.
Temperature readings are sent from the Feather nRF52840's Bluetooth-Low-Energy (BLE) radio to the [Adafruit BLE Connect App](https://learn.adafruit.com/bluefruit-le-connect).
## **Interactive Temperature Dashboard**
**[Adafruit IO](http://io.adafruit.com/) is the easiest way to stream, log, and interact with your data.** This project uses Adafruit IO to log and display temperature data on an interactive dashboard. You can check the current thermometer reading and monitor the temperature over time.
## Fever Email Alerts
If a temperature threshold is reached, **your armband sends an email to your phone**.
## Hands-Free and Rechargeable
We've designed this wearable armband to hold a rechargeable 3.7V 400mAh lipo battery. The Feather NRF52840 has an on-board lipo charger - plug it into micro-USB to charge between uses.
## About your Health Data and Adafruit IO
We won't share your account information with anyone without your permission and everything you store on Adafruit IO is **private by default** , whether you're a paying customer or not.
We believe Internet of Things devices should come with a well established expectation of what they will and will not do with consumer’s data.
- Read our [_Internet of Things Bill of Rights_](https://www.adafruit.com/iotbor/)
- Read the [_Adafruit IO Privacy Policy_](https://io.adafruit.com/terms)
- Read the [_Adafruit Privacy Policy_](https://www.adafruit.com/privacy)
## About this Project
- This project is _not_ a medical device.
- This project is _not_ waterproof or water-resistant
- This project is _not_ designed for use with children.
## Parts
The parts below were used in this project. You don't have to use the exact same parts but the enclosure was designed to specially fit these parts - so if you want to use different components, you can but just know it may not fit in the provided enclosure. You can of course tweak the CAD files.
### Adafruit Feather nRF52840 Express
[Adafruit Feather nRF52840 Express](https://www.adafruit.com/product/4062)
The **Adafruit Feather nRF52840 Express** is the new Feather family member with Bluetooth® Low Energy and _native USB support_ featuring the nRF52840! It's our take on an 'all-in-one' Arduino-compatible + Bluetooth® Low Energy with built-in USB...
In Stock
[Buy Now](https://www.adafruit.com/product/4062)
[Related Guides to the Product](https://learn.adafruit.com/products/4062/guides)
### Adafruit Feather nRF52840 Sense
[Adafruit Feather nRF52840 Sense](https://www.adafruit.com/product/4516)
The **Adafruit Feather Bluefruit Sense** takes our popular [Feather nRF52840 Express](https://www.adafruit.com/product/4062) and adds a smorgasbord of sensors to make a great wireless sensor platform. This Feather microcontroller comes with Bluetooth® Low Energy and...
In Stock
[Buy Now](https://www.adafruit.com/product/4516)
[Related Guides to the Product](https://learn.adafruit.com/products/4516/guides)
### MCP9808 High Accuracy I2C Temperature Sensor Breakout Board
[MCP9808 High Accuracy I2C Temperature Sensor Breakout Board](https://www.adafruit.com/product/1782)
This I2C digital temperature sensor is one of the more accurate/precise we've ever seen, with a typical accuracy of ±0.25°C over the sensor's -40°C to +125°C range and precision of +0.0625°C. They work great with any microcontroller using standard i2c. There are...
In Stock
[Buy Now](https://www.adafruit.com/product/1782)
[Related Guides to the Product](https://learn.adafruit.com/products/1782/guides)
### Breadboard-friendly SPDT Slide Switch
[Breadboard-friendly SPDT Slide Switch](https://www.adafruit.com/product/805)
These nice switches are perfect for use with breadboard and perfboard projects. They have 0.1" spacing and snap in nicely into a solderless breadboard. They're easy to switch no matter what size fingers you have, but not so easy that they'll get flipped by accident. Work great as...
In Stock
[Buy Now](https://www.adafruit.com/product/805)
[Related Guides to the Product](https://learn.adafruit.com/products/805/guides)
### Lithium Ion Polymer Battery Ideal For Feathers - 3.7V 400mAh
[Lithium Ion Polymer Battery Ideal For Feathers - 3.7V 400mAh](https://www.adafruit.com/product/3898)
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This battery has a capacity of **400mAh** for a total of about 1.9 Wh. If you need a larger (or smaller!)...
In Stock
[Buy Now](https://www.adafruit.com/product/3898)
[Related Guides to the Product](https://learn.adafruit.com/products/3898/guides)
### Silicone Cover Stranded-Core Ribbon Cable - 10 Wire 1 Meter Long
[Silicone Cover Stranded-Core Ribbon Cable - 10 Wire 1 Meter Long](https://www.adafruit.com/product/3890)
For those who are fans of our silicone-covered wires, but are always looking to _up their wiring game_. We now have **Silicone Cover Ribbon cables!** These may look _a lot_ like
In Stock
[Buy Now](https://www.adafruit.com/product/3890)
[Related Guides to the Product](https://learn.adafruit.com/products/3890/guides)
## Tools
Having the right tools makes this build easier and more fun. Most of these are available in the shop but use whatever tools you have on hand.
- [3D Printer](https://www.adafruit.com/categories/245) and [Filament](https://www.adafruit.com/products/2080) (or a 3D Printing Service)
### Part: Soldering Iron
quantity: 1
Hakko FX-888D
[Soldering Iron](https://www.adafruit.com/product/1204)
### Part: Flush Cutters
quantity: 1
Flush diagonal cutters - CHP170
[Flush Cutters](https://www.adafruit.com/product/152)
### Part: Wire Strippers
quantity: 1
Hakko Professional Quality 20-30 AWG Wire Strippers
[Wire Strippers](https://www.adafruit.com/product/527)
### Part: Panavise Jr
quantity: 1
Panavise Jr. - PV-201
[Panavise Jr](https://www.adafruit.com/product/151)
### Part: Helping Hands
quantity: 1
Helping Third Hand Magnifier W/Magnifying Glass
[Helping Hands](https://www.adafruit.com/product/291)
### Part: Screwdriver
quantity: 1
65 Piece Ratchet Screwdriver and Tool Bit Set
[Screwdriver](https://www.adafruit.com/product/829)
## Materials
Wires, screws, magnets, filament - The supplies listed below are both helpful and necessary for completing this project.
### Part: 3D Printer Filament
quantity: 1
Filament for 3D Printers in Various Colors and Types
[3D Printer Filament](https://www.adafruit.com/product/2080)
### Part: 10-wire Silicone Cover Stranded-core Wire
quantity: 1
28AWG 10-wire ribbon cable
[10-wire Silicone Cover Stranded-core Wire](https://www.adafruit.com/product/3890)
### Part: Heat Shrink
quantity: 1
Multi-Colored Heat Shrink Pack - 3/32" + 1/8" + 3/16" Diameters
[Heat Shrink](https://www.adafruit.com/product/1649)
### Part: Solder, Rosin-Core
quantity: 1
Mini Solder spool - 60/40 lead rosin-core
[Solder, Rosin-Core](https://www.adafruit.com/product/145)
### Part: Micro USB Cable
quantity: 1
Pink and Purple Braided USB A to Micro B Cable - 2 meter long
[Micro USB Cable](https://www.adafruit.com/product/4148)
# Wearable Continuous Temperature Monitor with Adafruit IO
## Circuit Diagram
The diagram below provides a visual reference for wiring of the components. This diagram was created using the software package [Fritzing](http://fritzing.org/download/).
## Adafruit Library for Fritzing
Use Adafruit's Fritzing parts library to create circuit diagrams for your projects. Download the library or just grab individual parts. Get the library and parts from [GitHub - Adafruit Fritzing Parts](https://github.com/adafruit/Fritzing-Library/tree/master/parts).
Make the following connections between the Feather NRF52840 and the MCP9808
- **Feather 3V** to **sensor Vdd**
- **Feather GND** to **sensor GND**
- **Feather SCL** to **sensor SCL**
- **Feather SDA** to **sensor SDA**
Make the following connections between the Feather NRF52840 and a SPDT slide-switch
- **Feather GND ** to **Center Switch Pin**
- **Feather EN** to **One of the outer pins on the switch**
Note that the Feather **GND** pad is shared between the MCP9808 and the switch.
# Wearable Continuous Temperature Monitor with Adafruit IO
## 3D Printing
## Parts
These parts are designed for FDM 3D printing. Parts are designed for support free 3D printing. List of parts:
- wctm-case.stl
- wctm-bottom.stl
- wctm-strap-sensor.stl
- wctm-loop-band.stl
- wctm-sensor-cover.stl
## Case Assembly
The case was designed in Autodesk Fusion 360 and features sketches and editable user parameters. The design source is available to download in STEP and other file formats.
## Sensor Assembly
The MCP9808 temperature sensor breakout is mounted to a flexible armband. The breakout PCB is press fitted onto built-in posts on the armband. Because the armband is printed flexible material, the posts can be forced through the mounting holes.
[Download CAD from Fusion 360](https://a360.co/3bCN4cr)
[Download CAD from Prusa Printers](https://www.prusaprinters.org/prints/28833-wearable-temperature-monitor)
[Download CAD from Thingiverse](https://www.thingiverse.com/thing:4268425)
## Flexible Parts
The sensor cover and two arm strap are designed for flexible filament. These parts must be printed in TPU material in order to function properly.
- wctm-strap-sensor.stl
- wctm-loop-band.stl
- wctm-sensor-cover.stl
## PLA Parts
The bottom cover and case are designed for rigid material like PLA or PETG. These do not require any support material.
## Design Source Files
The project assembly was designed in Fusion 360. This can be downloaded in different formats like STEP, STL and more. Electronic components like Adafruit's board, displays, connectors and more can be downloaded from the [Adafruit CAD parts GitHub Repo](https://github.com/adafruit/Adafruit_CAD_Parts).
[Adafruit CAD Parts on GitHub](https://github.com/adafruit/Adafruit_CAD_Parts)
# Wearable Continuous Temperature Monitor with Adafruit IO
## Assembly
## Wiring Circuit
Solder the MCP9808 sensor and slide switch to the pins on the Feather nRF52840. 10-wire 28AWG silicone covered wire is suggested. Use the following wire lengths:
**MCP9808 4-Wire Cable**
160mm (6.3in)
**Slide Switch 2-Wire Cable**
50mm (2in)
Info:
## Install Feather nRF52840
Place the Feather PCB on top of the standoffs on the bottom cover. Reference the photo for correct placement. Insert the PCB at an angle so the edge is underneath one of the tabs. Fit one of the mounting holes onto one of the standoffs.
## Secure Feather
Firmly press the PCB down so it clips under the second tab. The two tabs will keep the Feather secured in place. Ensure the second mounting hole is properly fitted onto the standoff.
## Installed PCB
The Feather PCB should be flush like shown in the photo. A clearance of 2mm allows for wiring on the bottom.
## Installing Switch
Insert the body of the slide switch to the built-in holder on the bottom cover. Firmly press the switch into the holder to secure it in place.
## Installed Switch
The actuator should be accessible on the outside of the holder.
## Install Parts
The 400mah lipo battery can be secured in place with double-sided tap or mounting tack. Double check the slide switch and Feather nRF52840 are properly installed.
## Install Flexible Strap
Insert the tabbed end of the strap to the slotted tab on the bottom cover closest to the Feather.
## Install MCP9808
Place the MCP9808 PCB over the two nubs on the end of the flexible strap. Firmly press the nubs into the two mounting holes on the MCP9808 PCB.
## Installed MCP9808
The nubs are essentially squeezed into the mounting holes – This is only possible with flexible material like Ninjaflex, Cheetach or TPU filament.
## Install Sensor Cover
Slip the cover onto the flexible strap to protect the MCP9808 sensor. The center hole in the cover should be properly lined up with the temperature sensor – if not, reverse the orientation of the cover.
## Installing MCP9808 Wiring
Pinch the flexible strap to open up the channel in the middle of the band. Begin to fit the 4-wire ribbon cable into the channel. Press wiring down so it's flattened into place.
## Installed Wiring
The silicone covered ribbon cable provides a nice grip combined with the flexible strap. By Design, the wiring will be kept in place when bending the strap inwards or outwards.
## Install Case to Bottom
The case snap fits onto the bottom cover. Line up the cutouts with the features on the bottom cover. The case features a cutaway for the sensor wiring.
## Sensor Wiring Clearance
The wiring from the sensor is fitted through the opening on the side of the case.
## Install Loop Band to Strap
Insert the loop band through the end on the flexible strap.
## Tension Loop
Grab the nub end of the loop brand and fit it through the two slots. Reference the photo for correct installation.
## Installed Loop Band
Fit the nub end of the loop band through the slotted tab on the bottom cover. Firmly press the nub end through.
## USB Access
The USB port is accessible for recharging the 400mah lipo battery and reprogramming.
## Power Switch
Use the slide switch to power the circuit on and off.
## Assembled Case
And there we have it! The case is assembled and ready to wear.
# Wearable Continuous Temperature Monitor with Adafruit IO
## Adafruit IO Setup
## Feed Setup
If you do not already have an Adafruit IO account set up, head over to [io.adafruit.com](http://io.adafruit.com/) to link your Adafruit.com account to Adafruit IO.
The first step is to create a new Adafruit IO feed to hold the data from the temperature sensor. Navigate to the [feeds page](https://io.adafruit.com/feeds) on Adafruit IO. Then click **Actions -\> Create New Feed** , and name this feed **rx**.
- If you do not already know how to create a feed, head over to [Adafruit IO Basics: Feeds](https://learn.adafruit.com/adafruit-io-basics-feeds).
## Dashboard Setup
Now that we have feeds to hold data and display the type of data, we need a way to consolidate these feeds in one place. Dashboards are a feature of Adafruit IO which allow us to display and control feeds using widgets called _Blocks_.
- If you haven't used an Adafruit IO Dashboard before, [check out the _Adafruit IO Basics: Dashboards_ learn guide](https://learn.adafruit.com/adafruit-io-basics-dashboards) for a quick primer.
- **Navigate** to [the Adafruit IO Dashboards page](https://io.adafruit.com/dashboards).
- From the Actions dropdown, **click Create a New Dashboard**.
- **Name** the dashboard **Temperature Armband.**
## Add Line Chart Block
The MCP9808 temperature sensor sends data to Adafruit IO once per minute. We'll want a way of displaying historical data on the dashboard. From the dashboard, **click the + button to create a new block.**
From the modal, ** Click the Line Chart** block.
- **Search** for the _rx_ feed.
- **Click the checkbox** next to the feed.
- **Click** Next Step
- **Name the Block Title** to _Temperature (4 Hours)_
- **Set Show History** to 4 hours
## Add Gauge Block
A gauge is a read only block type that shows a fixed range of values. We'll add a gauge block to display the real-time value from the wearable temperature monitor in _real-time_
- **Select** the _rx_ feed.
- **Set the Block Title** to Temperature.
- **Set the Gauge Min Value** to 94 (or 34 if you're measuring degrees Celsius).
- **Set the Gauge Max Value** to 107.6 (or 42 if you're measuring degrees Celsius).
- **Set the Gauge Width** to 50px.
- **Set the Gauge Label** to Degrees F (or Degrees C if you're measuring degrees Celsius).
The gauge will change color if the value goes out of bounds.
- **Set a Low Warning Value** to 96.
- **Set the High Warning Value** to 100.4
Set Decimal Places to display to 1.
You may also optionally show an icon next to the value. To do this:
- **Tick the Show Icon checkbox**
- **Set the icon** to _thermometer_
Your dashboard should look like the screenshot below:
## Action Setup
Actions are a way to do something when a certain situation occurs. We'll be[using a reactive action](https://learn.adafruit.com/all-the-internet-of-things-episode-four-adafruit-io/triggers#reactive-triggers-10-8) to email us if the _rx_ feed receives a value from the thermometer above our fever-threshold.
Warning:
Info:
**Navigate to** [your Adafruit IO account's Triggers page](https://io.adafruit.com/triggers). **Click Actions** , then click **Create a New Action**
**Select ** the **Reactive Action**
Next, we'll configure the action.
- Under If, **select the rx action feed**.
- For the comparison, **select Greater Than or Equal to**.
- For the Comparison Value or Feed, **enter 102** (we're in the US, so our fever threshold is measured in degrees Fahrenheit. Change this value to 38.9 if you're planning to measure temperature in degrees Celsius).
- **Select email me** for the action.
## Obtain Adafruit IO Key
You are also going to need your Adafruit IO username and secret API key.
**[Navigate to your profile](http://io.adafruit.com/profile) and click the View AIO Key button** to retrieve them. Write them down in a safe place, you'll need them for the next step.
# Wearable Continuous Temperature Monitor with Adafruit IO
## Arduino Code
This guide assumes you've set up the Adafruit Bluefruit nRF52 Board Support Package.
- If you have not yet done this, [navigate to this page and come back when you've installed the package](https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather/arduino-bsp-setup).
Before proceeding with the code in this guide, you should be able to run the blinky sketch from the Arduino IDE.
- If you have not uploaded code to your Feather NRF52, [navigate to this page and come back when you've successfully uploaded code to the Feather NRF52](https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather/arduino-board-setup).
Make sure your board is selected:
- Go to the **Tools** menu
- Select **Tools \> Board \> Adafruit Bluefruit nRF52840 Feather Express**
**Copy the code below** to the Arduino IDE. **Click verify**. Then, **click Upload**.
https://github.com/adafruit/Adafruit_Learning_System_Guides/blob/main/Wearable_BLE_Temperature_Monitor/Wearable_BLE_Temperature_Monitor.ino
After you've successfully uploaded the code to your Feather, **toggle the switch to turn the power on**. The blue LED labeled CONN should blink.
# Wearable Continuous Temperature Monitor with Adafruit IO
## Usage
## Wearing Your Monitor
Slip your arm through the straps with the band facing out. The sensor should be located underneath your armpit when you place your arm at your side.
Use the loop strap to loosen or tighten the band. Adjust the armband until it no longer slides around your arm. Make sure it is not too tight, you do not want to cut off circulation.
## Bluefruit LE Connect Usage
The [**Adafruit Bluefruit LE Connect app**](https://learn.adafruit.com/bluefruit-le-connect) provides iOS & Android devices with a variety of tools to communicate with Bluefruit LE devices such as the Feather NRF52840. We'll be using Bluefruit LE Connect App to send temperature data using the MQTT protocol to [Adafruit IO](http://io.adafruit.com/).
- If you have not yet installed the Bluefruit LE Connect app and set up your phone, [follow this page and come back to this page when you're done](https://learn.adafruit.com/bluefruit-le-connect/ios-setup).
Once installed, **open the Bluefruit LE Connect app**. The app will automatically begin to scan for nearby Bluetooth LE devices.
**Tap the Connect button** next to the the **Bluefruit52** device discovered by the app.
- If you're having trouble finding your Bluefruit device in the scanned peripherals list, [visit this page for troubleshooting steps.](https://learn.adafruit.com/bluefruit-le-connect/scan-for-devices#troubleshooting-2-14)
Once connected, the Bluefruit connect app will list its available modes. **Tap the UART mode.**
Next, you'll need to configure the Bluefruit LE Connect App's MQTT client with your Adafruit IO account information.
- If you have not done this yet, [follow this guide and come back to this page when you're done](https://learn.adafruit.com/bluefruit-le-connect/mqtt#configuration-6-3).
Once configured, **tap Connect**
The MQTT Status will change to Connected, indicating that you've successfully connected to the Adafruit IO MQTT server.
- If you are not able to connect to Adafruit IO, [carefully re-read this guide and try re-connecting](https://learn.adafruit.com/bluefruit-le-connect/mqtt#configuration-6-3).
## Code Usage
### Temperature Sensor Calibration
After connecting to the Bluefruit Connect App, the the armband will take twelve minutes to fully calibrate.
- Your armpit provides an **axillary temperature.** Measuring your armpit temperature [for a minimum of 12 minutes is equivalent to measuring your core body temperature](https://www.ncbi.nlm.nih.gov/pubmed/21145551).
Make sure the sensor is in your armpit and that your arm is **firmly pressed against your side.** After twelve minutes have passed, temperature readings will display on the UART monitor.
## Viewing Sensor Data on Adafruit IO
Navigate to the Adafruit IO dashboard you created earlier. After 12 minutes have passed, the gauge and line block will update with the current temperature reading every minute. The line graph block updates and display the previous four hours of temperature data.
## Fever Notifications
The reactive trigger you set up earlier will email you if the temperature increases beyond a temperature threshold.
If the temperature increases above the threshold you set, the Gauge block will change from a cool blue to bright yellow.
## Configure the Fever Temperature Threshold
The Feather NRF52840's built-in NeoPixel will glow bright red if the temperature is above a configurable fever threshold. To change this value in the code, change the following line from:
`// Maximum temperature value for armband's fever indicator`
`// NOTE: This is in degrees Fahrenheit`
`float fever_temp = 100.4;`
to
`// Maximum temperature value for armband's fever indicator`
`// NOTE: This is in degrees Fahrenheit`
`float fever_temp = DESIRED_FEVER_TEMPERATURE;`
## Change the Sensor Read Delay
By default, the code sends data to Adafruit IO every minute, then puts the temperature sensor and the NRF52840 to sleep.
If you want to change this code to read data at faster or slower intervals, change the following line from:
`// Sensor read delay, in minutes`
`int sensor_delay = 1;`
to
`// Sensor read delay, in minutes`
`int sensor_delay = DESIRED_SENSOR_DELAY;`
Keep in mind that every time the loop is executed, the microcontroller wakes up, executes code, and wirelessly sends data. You may want to increase the delay to conserve power.
## Featured Products
### Adafruit Feather nRF52840 Express
[Adafruit Feather nRF52840 Express](https://www.adafruit.com/product/4062)
The **Adafruit Feather nRF52840 Express** is the new Feather family member with Bluetooth® Low Energy and _native USB support_ featuring the nRF52840! It's our take on an 'all-in-one' Arduino-compatible + Bluetooth® Low Energy with built-in USB...
In Stock
[Buy Now](https://www.adafruit.com/product/4062)
[Related Guides to the Product](https://learn.adafruit.com/products/4062/guides)
### Adafruit Feather nRF52840 Sense
[Adafruit Feather nRF52840 Sense](https://www.adafruit.com/product/4516)
The **Adafruit Feather Bluefruit Sense** takes our popular [Feather nRF52840 Express](https://www.adafruit.com/product/4062) and adds a smorgasbord of sensors to make a great wireless sensor platform. This Feather microcontroller comes with Bluetooth® Low Energy and...
In Stock
[Buy Now](https://www.adafruit.com/product/4516)
[Related Guides to the Product](https://learn.adafruit.com/products/4516/guides)
### MCP9808 High Accuracy I2C Temperature Sensor Breakout Board
[MCP9808 High Accuracy I2C Temperature Sensor Breakout Board](https://www.adafruit.com/product/1782)
This I2C digital temperature sensor is one of the more accurate/precise we've ever seen, with a typical accuracy of ±0.25°C over the sensor's -40°C to +125°C range and precision of +0.0625°C. They work great with any microcontroller using standard i2c. There are...
In Stock
[Buy Now](https://www.adafruit.com/product/1782)
[Related Guides to the Product](https://learn.adafruit.com/products/1782/guides)
### Breadboard-friendly SPDT Slide Switch
[Breadboard-friendly SPDT Slide Switch](https://www.adafruit.com/product/805)
These nice switches are perfect for use with breadboard and perfboard projects. They have 0.1" spacing and snap in nicely into a solderless breadboard. They're easy to switch no matter what size fingers you have, but not so easy that they'll get flipped by accident. Work great as...
In Stock
[Buy Now](https://www.adafruit.com/product/805)
[Related Guides to the Product](https://learn.adafruit.com/products/805/guides)
### Lithium Ion Polymer Battery Ideal For Feathers - 3.7V 400mAh
[Lithium Ion Polymer Battery Ideal For Feathers - 3.7V 400mAh](https://www.adafruit.com/product/3898)
Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This battery has a capacity of **400mAh** for a total of about 1.9 Wh. If you need a larger (or smaller!)...
In Stock
[Buy Now](https://www.adafruit.com/product/3898)
[Related Guides to the Product](https://learn.adafruit.com/products/3898/guides)
### Pink and Purple Braided USB A to Micro B Cable - 2 meter long
[Pink and Purple Braided USB A to Micro B Cable - 2 meter long](https://www.adafruit.com/product/4148)
This cable is super-fashionable with a woven pink and purple Blinka-like pattern!
First let's talk about the cover and over-molding. We got these in custom colors, and if you _have_ to have visible cables, then you might as well have the nicest fabric-bound...
No Longer Stocked
[Buy Now](https://www.adafruit.com/product/4148)
[Related Guides to the Product](https://learn.adafruit.com/products/4148/guides)
### Silicone Cover Stranded-Core Ribbon Cable - 10 Wire 1 Meter Long
[Silicone Cover Stranded-Core Ribbon Cable - 10 Wire 1 Meter Long](https://www.adafruit.com/product/3890)
For those who are fans of our silicone-covered wires, but are always looking to _up their wiring game_. We now have **Silicone Cover Ribbon cables!** These may look _a lot_ like
In Stock
[Buy Now](https://www.adafruit.com/product/3890)
[Related Guides to the Product](https://learn.adafruit.com/products/3890/guides)
## Related Guides
- [Introducing the Adafruit nRF52840 Feather](https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather.md)
- [Adafruit Feather nRF52840 Sense](https://learn.adafruit.com/adafruit-feather-sense.md)
- [BLE Sniffer with nRF52840](https://learn.adafruit.com/ble-sniffer-with-nrf52840.md)
- [Bluetooth Controlled NeoPixel Lightbox](https://learn.adafruit.com/bluetooth-neopixel-lightbox.md)
- [Busy Box Interruption Sign](https://learn.adafruit.com/busy-box-interruption-sign.md)
- [CircuitPython I2C and SPI Under the Hood](https://learn.adafruit.com/circuitpython-basics-i2c-and-spi.md)
- [Mouse and Keyboard Control Using TinyUSB and BLE](https://learn.adafruit.com/mouse-and-keyboard-control-using-tinyusb-and-ble.md)
- [CircuitPython BLE Advertising Beacons](https://learn.adafruit.com/circuitpython-ble-advertising-beacons.md)
- [Doomscroll and Chill - A Wireless BLE Scroll Wheel Remote](https://learn.adafruit.com/doomscroll-and-chill-wireless-ble-scroll-wheel-rotary-encoder-remote.md)
- [Introduction to Bluetooth Low Energy](https://learn.adafruit.com/introduction-to-bluetooth-low-energy.md)
- [BLE Buzzy Box](https://learn.adafruit.com/ble-buzzy-box.md)
- [Speech Synthesis on the Raspberry Pi](https://learn.adafruit.com/speech-synthesis-on-the-raspberry-pi.md)
- [BLE HID Keyboard Buttons with CircuitPython](https://learn.adafruit.com/ble-hid-keyboard-buttons-with-circuitpython.md)
- [MCP9808 Temperature Sensor Python Library](https://learn.adafruit.com/mcp9808-temperature-sensor-python-library.md)
- [Programmable Wireless BLE Gesture Mouse](https://learn.adafruit.com/ble-wireless-gesture-mouse.md)
- [All the Internet of Things - Episode Three: Services](https://learn.adafruit.com/all-the-internet-of-things-episode-three-services.md)
- [Pulse Oximeter Wireless Data Logger](https://learn.adafruit.com/pulse-oximeter-wireless-data-logger.md)