Micropython MQTT over USB_Net Demo

This demo app is intended to show basic usage of mqtt communication over a USB Network interface from PC to Micropython, currently running on a Raspberry Pi Pico.

This utilises the USB Network endpoint provided in the PR: shared/tinyusb: Add support for USB Network (NCM) interface.

It has been tested with the Mosquitto mqtt broker on Windows 11.

Installation

1. Install Mosquitto: https://mosquitto.org/download/

2. Update the Firewall and Mosquitto config file to enable access from other devices.

   • Open a powershell terminal in administrator mode to add firewall rule edit config file
   • Add a firewall rule:

   New-NetFirewallRule -DisplayName "Allow Mosquitto MQTT" -Direction Inbound -Program "C:\Program Files\mosquitto\mosquitto.exe" -RemoteAddress 169.254.0.0/255.255.0.0 -Action Allow
   

   • Update the config file:

   Add-Content -Path "C:\Program Files\mosquitto\mosquitto.conf" -Value "`n`nlistener 1883 0.0.0.0"
   Add-Content -Path "C:\Program Files\mosquitto\mosquitto.conf" -Value "allow_anonymous true"
   

   • Restart the service:

   restart-service mosquitto
   

3. Install MQTT Explorer: https://mqtt-explorer.com/ and open it, connect to localhost on port 1883 (tls disabled)

4. In a local clone of micropython, apply the PR linked above: gh pr checkout 16459

5. Build micropython for RPI_PICO with USB_NET variant: mpbuild build RPI_PICO USB_NET

6. Plug the rpi pico into USB with the BOOTSEL pushbutton held down. Then copy the firmware to the USB drive that pops up, eg.
   copy micropython\ports\rp2\build-RPI_PICO-USB_NET\firmware.uf2 E:\

7. Once copied, the pico should reboot automatically and be detected as both a USB Serial device and a USB Network interface.

8. Open a terminal in this repo folder.

9. Install the dependencies:

mpremote mip install aiorepl

mpremote mip install --target="lib/primitives" "github:peterhinch/micropython-async/v3/primitives/__init__.py"
mpremote mip install --target="lib/primitives" "github:peterhinch/micropython-async/v3/primitives/broker.py"
mpremote mip install --target="lib/primitives" "github:peterhinch/micropython-async/v3/primitives/queue.py"
mpremote mip install --target="lib/primitives" "github:peterhinch/micropython-async/v3/primitives/ringbuf_queue.py"

1. Load this demo script: mpremote mount . repl --inject-code "import mqtt_demo\n"

2. The repl should appear, at which point you can hit Ctrl-J to run the application.

PS mqtt_demo\> mpremote mount . repl --inject-code "import mqtt_demo\n"
Local directory . is mounted at /remote
Connected to MicroPython at COM33
Use Ctrl-] or Ctrl-x to exit this shell
Use Ctrl-J to inject b'import mqtt_demo\r\n'
>
MicroPython v1.25.0-preview.342.g89f246acb7.dirty on 2025-03-03; Raspberry Pi Pico with RP2040
Type "help()" for more information.
>>> import mqtt_demo
Connecting to host: 169.254.128.16
Connectd.
Subscribing
Starting asyncio REPL...
--> 

1. Try pressing the button on the pico, it should be reported on the repl

2. You should also see it pop up in MQTT Explorer!

3. In Mqtt Explorer try publishing any text to the topic: led_topic, you should see it pop up in the repl! and the led on the pico should toggle!