Flashing your own code to nrf52811-solum-tag using a raspberry pico as a debug probe

Foreword:

I recently got a Solum EL029H4WRC price tag (N52811 chip) and decided to flash my own code to it and use the tag as a conference badge. Since I haven't got a real debug probe, I decided to use a raspberry pi pico for this purpose. Below I describe steps for anyone to reproduce my approach, that happens to be the quickest and most affordable solution among the currently existing.

I'm not going to cover a whole process of how I came to the solution, just simple steps to reproduce the result. If you are interested in more complex uses including wireles communications via zigbee, please check this https://github.com/OpenEPaperLink/OpenEPaperLink

STEP 1 - setup the pico-probe

It is a quite straigth forward step:

• go to https://github.com/raspberrypi/debugprobe/releases/tag/debugprobe-v2.2.1
• download the uf2 file
• flash it to your raspberry pi pico

Make sure you have probe-rs installed: https://probe.rs/

STEP 2 - connect the tag to the pico probe, to use the pico as a flasher

• Since the tag has no usb, we need to use debug pins ^_^ I highlighted pins, we will use, in red on an img below.

Pinout:

TAG	PICO
VCC	36
GND	3
CLK	4
DIO	5

• Since there is only 4 pins, you can simply glue them to get a kinda connector, or solder if you are comfortable with it.

STEP 3 - flash example code

• clone this repo
• cargo build --release
• connect the pico probe to debug pins of the tag
• probe-rs download --chip nRF52811_xxAA target/thumbv7em-none-eabi/release/nrf52811-solum-tag
• keep connected till a code is flashed (like 2 secs)

Demo To-Do

• Display text;
• Display image (bmp);
• Activate 3 Leds;
• Enable wireless update;