Tinygo - Bluetooth with nrf52840 dongle

The nrf52840 dongle is a small cheap device which I feel is perfect for hobby projects.

tinygo has strong bluetooth support for nrf devices.

However, getting the nrf52840 dongle flashed takes a few steps, this document is what worked for me.

Prerequisites

• tinygo and go
• Install nrfutil
• dongle must still have its factory bootloader intact

Clone the bluetooth repository, this gives us access to examples, but also the required SoftDevice binary:

git clone https://github.com/tinygo-org/bluetooth.git
cd bluetooth

First Flash with SoftDevice

The first time we flash our dongle, we need to combine our binary with the SoftDevice binary to access bluetooth functionality

Build Our App

Build against pca10059-s140v7.

tinygo build -target=pca10059-s140v7 -o app.hex ./examples/heartrate

• pca10059-s140v7 links the application above the S140 v7 SoftDevice region.
  • note: if we targeted pca10059, the application would be placed where the SoftDevice region would be, so pca10059 is incompatable with the bluetooth package.
• We use .hex instead of .bin to specify to the DFU tool where to place the binary

Package with SoftDevice

The tinygo-org/bluetooth repository includes the SoftDevice hex. Find it’s location in the repository, I found it in s140_nrf52_7.3.0/s140_nrf52_7.3.0_softdevice.hex.

Package the binaries together using nrfutil:

nrfutil nrf5sdk-tools pkg generate \
  --hw-version 52 \
  --sd-req 0x00 \
  --sd-id 0x0123 \
  --softdevice s140_nrf52_7.3.0/s140_nrf52_7.3.0_softdevice.hex \
  --application app.hex \
  --application-version 1 \
  fw.zip

• --hw-version 52 - 52 is Nordic’s convention for nrf52 boards
• --sd-req 0x00 - indicates no SoftDevice is currently on target
• --sd-id 0x0123 - the firmware ID of the SoftDevice being used
  • This references the s140 v7.3.0 firmware ID
  • You can see the list of all firmware IDs by calling nrfutil nrf5sdk-tools pkg generate --help

Flash the Dongle

Find which port the dongle has connected to. It can be helpful to use nrfutil device list - if the device package isn’t installed, nrfutil install device first:

nrfutil device list   
  0
  Product         USB2.0 Hub             
  Ports           /dev/tty.usbmodem13101
  Traits          nordicUsb, serialPorts, usb

  Found 1 supported device

Once we know the dongle’s port, we can flash it:

nrfutil nrf5sdk-tools dfu usb-serial --package fw.zip --port /dev/tty.usbmodem13101

Flashing Without SoftDevice

Packaging and flashing with SoftDevice only needs to be done once.

For subsequent updates:

tinygo build -target=pca10059-s140v7 -o app.hex ./examples/heartrate

nrfutil nrf5sdk-tools pkg generate \
  --hw-version 52 \
  --sd-req 0x0123 \
  --application app.hex \
  --application-version 1 \
  app.zip

nrfutil nrf5sdk-tools dfu usb-serial --package app.zip --port /dev/ttyACM0

Note, we now use --sd-req 0x0123 - we require that this soft device is loaded.