Compiling and Testing on a remote microcontroller

Recently I've been doing a lot of microcontroller work. And I've wanted to offload compiling code as well as having the microcontroller hosted without carrying it around. These microcontrollers could be Arduino/esp32 etc.

I've got an Intel NUC that I've set up to automatically connect to my Wireguard server. This means I always have the same IP to connect to as well as remote access if I'm not on the same LAN.

Finally, I'd like to avoid using the Arduino IDE as I find it very limited in capability.

I believe most of this could be dockerized but let's keep it simple for now.

On Ubuntu 20.

Installing the Arduino CLI instructions can be found here. Brew installs are available if you'd prefer to use a mac.

mkdir ~/.local/bin &&
curl -fsSL https://raw.githubusercontent.com/arduino/arduino-cli/master/install.sh | BINDIR=~/.local/bin sh

Let us also add some additional boards, open the CLI config.

nano ~/.arduino15/arduino-cli.yaml

Add the esp boards.

board_manager:
  additional_urls:
    - http://arduino.esp8266.com/stable/package_esp8266com_index.json
    - https://dl.espressif.com/dl/package_esp32_index.json

Update and install the boards you need.

arduino-cli core update-index && core install esp32:esp32

Now if you plug in an ESP32 and run list

arduino-cli board list

You should see the board.

Port         Type              Board Name FQBN Core
/dev/ttyUSB0 Serial Port (USB) Unknown

Let us create a new Arduino sketch.

arduino-cli sketch my_sketch

At this point, I've set up my Pycharm IDE to auto-deploy and sync the project folder over SSH.

Lets make our ESP32 blink

#include "wifi_info.h"

int led = 2;

void setup() {
  Serial.begin(9600);
  Serial.println("Stepper test!");
  // initialize the digital pin as an output.
  pinMode(led, OUTPUT);
}

void loop() {
    Serial.println("Stepper high!");
    digitalWrite(led, HIGH);
    delay(1000);               // wait for a second
    Serial.println("Stepper low!");
    digitalWrite(led, LOW);
    delay(1000);               // wait for a second
}

Now we have a bash script that checksums our sketch folder and compiles and uploads our code if anything changes. After which it starts a miniterm session to listen to the serial console.

# sh deploy.sh
arduino_cli=~/.local/bin/arduino-cli
SRC="my_sketch"
PORT="/dev/ttyUSB0"
BOARD="esp32:esp32:esp32"
INPUT=""

CHECKSUM_FILE=.checksum

touch $CHECKSUM_FILE
CHECKSUM_SRC=$(grep -ar -e . --include="*.ino" --include="*.h" --include="*.c" $SRC | cksum | cut -c-32)

PREVIOUS_CHECKSUM=`cat $CHECKSUM_FILE`
CHECKSUM="$CHECKSUM_SRC"

if [ ! "$CHECKSUM" = "$PREVIOUS_CHECKSUM" ]; then
    echo "Different checksums building and deploying"
    $arduino_cli compile \
    --fqbn $BOARD \
    $SRC

    $arduino_cli upload \
    --port $PORT \
    --fqbn $BOARD \
    $SRC

    echo $CHECKSUM > $CHECKSUM_FILE
else
    echo "No differences detected running existing binary."
fi

echo "Listening on Port"

miniterm $PORT 9600

To call this script over ssh (we could make this into another script if ya catch my drift) we can run.

ssh -t -t [email protected] "cd ~/code/my_sketch && bash deploy.sh"

Thats it now we should be seeing the output from the serial port.

--- Miniterm on /dev/ttyUSB0  9600,8,N,1 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
Stepper test!
Stepper low!
Stepper high!
Stepper low!
Stepper high!
...