microcontrollers: add feather-nrf52840-sense

Author: sago35

content/docs/reference/microcontrollers/feather-nrf52840-sense.md

@@ -0,0 +1,100 @@
+---
+title: "Adafruit Feather nRF52840 Sense"
+weight: 3
+---
+
+The [Adafruit Feather nRF52840 Sense](https://www.adafruit.com/product/4516) is a small ARM development board based on the Nordic Semiconductor [nrf52840](https://www.nordicsemi.com/eng/Products/nRF52840) processor.
+
+## Interfaces
+
+| Interface | Hardware Supported | TinyGo Support |
+| --------- | ------------- | ----- |
+| GPIO      | YES | YES |
+| UART      | YES | YES |
+| SPI      | YES | YES |
+| I2C      | YES | YES |
+| ADC      | YES | YES |
+| PWM      | YES | YES |
+| Bluetooth      | YES | YES |
+
+## Machine Package Docs
+
+[Documentation for the machine package for the Adafruit Feather nRF52840 Sense](../machine/feather-nrf52840-sense)
+
+## Flashing
+
+### UF2
+
+The Adafruit Feather nRF52840 Sense comes with the [UF2 bootloader](https://github.com/Microsoft/uf2) already installed.
+
+**PLEASE NOTE** that for a good experience using TinyGo on your board you must be running version 0.4.1 or above of the UF2 bootloader on the board. For more information, [see below](#updating-the-uf2-bootloader)
+
+### CLI Flashing
+
+- Plug your Adafruit Feather nRF52840 Sense into your computer's USB port.
+- Flash your TinyGo program to the board using this command:
+
+    ```shell
+    tinygo flash -target=feather-nrf52840-sense [PATH TO YOUR PROGRAM]
+    ```
+
+- The Adafruit Feather nRF52840 Sense board should restart and then begin running your program.
+
+### Troubleshooting
+
+If you have troubles getting your Adafruit Feather nRF52840 Sense board to receive code, try this:
+
+- Press the "RESET" button on the board two times to get the Adafruit Feather nRF52840 Sense board ready to receive code.
+- The Adafruit Feather nRF52840 Sense board will appear to your computer like a USB drive.
+- Now try running the command:
+
+    ```shell
+    tinygo flash -target=feather-nrf52840-sense [PATH TO YOUR PROGRAM]
+    ```
+
+Once you have updated your Adafruit Feather nRF52840 Sense board the first time, after that you should be able to flash it entirely from the command line.
+
+## Notes
+
+You can use the USB port to the Adafruit Feather nRF52840 Sense as a serial port. `UART0` refers to this connection.
+
+Bluetooth support is now available for the Adafruit Feather nRF52840 Sense board. See https://github.com/tinygo-org/bluetooth for more information.
+
+## Updating the UF2 bootloader
+
+This board uses a UF2 bootloader created by Adafruit: https://github.com/adafruit/Adafruit_nRF52_Bootloader
+
+We recommend bootloader version 0.4.1 or above. You can check what version is installed on your board by double-clicking the button on the board to launch the bootloader. When you do this, a USB volume that should automatically be mounted on your computer. Check the file named "INFO_UF2.TXT" on that drive. The bootloader firmware version should be listed in that file, for example:
+
+```
+UF2 Bootloader 0.4.1 lib/nrfx (v2.0.0) lib/tinyusb (0.6.0-272-g4e6aa0d8) lib/uf2 (remotes/origin/configupdate-9-gadbb8c7)
+Model: Adafruit CLUE nRF52840
+Board-ID: nRF52840-CLUE-revA
+SoftDevice: S140 version 6.1.1
+Date: Jan 19 2021
+```
+
+To update the bootloader, you will need to install the `adafruit-nrfutil` program. 
+
+You can install it by running:
+
+```shell
+pip3 install --user adafruit-nrfutil
+```
+
+Once you have installed the `adafruit-nrfutil` program, download the firmware here: 
+https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/download/0.4.1/feather_nrf52840_sense_bootloader-0.4.1.zip
+
+Unzip the files in this zip file and save them to a convenient location. 
+
+Plug in your board to your computer's USB port.
+
+Now we are ready to update the firmware. Run a command something like the following, adjusting for any difference based on where you have saved the files, and what your serial port is named:
+
+```shell
+ adafruit-nrfutil --verbose dfu serial --package feather_nrf52840_bootloader-0.4.1_s140_6.1.1.zip -p /dev/ttyACM0 -b 115200 --singlebank --touch 1200
+```
+
+Note that you should be flashing the board using the zip file that was contained within the zip file that you downloaded, NOT the file that you downloaded.
+
+Once you have flashed the board with the `adafruit-nrfutil` it should restart the board with the new bootloader. You only need to do this update once, and then from that point on the new bootloader will be active.

content/docs/reference/microcontrollers/feather-nrf52840.md

@@ -83,7 +83,7 @@ pip3 install --user adafruit-nrfutil
 ```
 
 Once you have installed the `adafruit-nrfutil` program, download the firmware here: 
-https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/download/0.4.1/feather_nrf52832_bootloader-0.4.1.zip
+https://github.com/adafruit/Adafruit_nRF52_Bootloader/releases/download/0.4.1/feather_nrf52840_express_bootloader-0.4.1.zip
 
 Unzip the files in this zip file and save them to a convenient location.