mqtt_client_test

[ellebi2000]

This PR introduces functionality for temperature monitoring and LED control on a Raspberry Pi Pico W using MQTT. The key features include:

Temperature Monitoring:

Reads onboard temperature using the ADC.
Converts ADC readings to Celsius or Fahrenheit.
Publishes temperature to the /temperature MQTT topic every 5 seconds.

LED Control:

Controls the onboard LED via MQTT messages received on the /led topic.
Turns the LED on/off based on "On" or "Off" messages.
Publishes LED state to the /state MQTT topic.

WiFi and MQTT Configuration:

Connects to WiFi using predefined SSID and password.
Connects to the MQTT broker with the given IP address and port.
Configures an MQTT client with a predefined client ID and keep-alive period.

MQTT Callbacks:

mqtt_incoming_data_cb: Handles incoming data and controls the LED.
mqtt_incoming_publish_cb: Handles incoming publish events.
mqtt_connection_cb: Manages MQTT connection status and subscribes to the /led topic.

[martincarapia]

Don't mean to be picky, but I'm going through your code to include mqtt with my project and noticed this comment code all messed up

[ellebi2000]

You're right, it's in Italian. It was a comment written during development, and I didn't notice it when reviewing. I'll remove it in the next commit, sorry.

[martincarapia]

Everything checks out. I just tested it and the code runs great!

Just those little nitpicks and it's good to be approved!

[francdoc]

This implementation is working great. I tested your publisher sample with a subscriber from this repository (running on a Linux machine) simple_subscriber.c.

I configured your code to publish to the address "35.156.49.117" (broker.hivemq.com) on port 1883, and the MQTT-C subscriber successfully listened to the transmitted temperature data.

Thank you, ellebi2000.

[ellebi2000]

I have removed the comment in Italian and others that are not strictly necessary.
I'm very happy that your implementations are working as expected @martincarapia @francdoc

[lurch]

Could you add a comment clarifying the license that this code is released under please?

[lurch]

Rather than explicitly defining these here, it might be better to just pick them up "automatically" from the CMake settings? See https://github.com/raspberrypi/pico-examples/blob/master/pico_w/wifi/ntp_client/picow_ntp_client.c and https://github.com/raspberrypi/pico-examples/blob/master/pico_w/wifi/CMakeLists.txt and section 2.2 of https://datasheets.raspberrypi.com/picow/connecting-to-the-internet-with-pico-w.pdf

[lurch]

Perhaps this should be in pico_w/wifi/mqtt instead of pico_w/mqtt ?

EDIT: Also, do you really need separate mqtt and mqtt/mqtt_client directories? 🤔 Perhaps it could be "collapsed" to just a single pico_w/wifi/mqtt_client directory?

[lurch]

There's quite a few code-comments where you've said "Public blah blah topic" - were these supposed to say "Publish blah blah topic" ?

[lurch]

Blank line between functions please 🙂 (both here and in a few other places)

[lurch]

Would it be better to use strncpy here? 🤷

[lurch]

No need to do tight_loop_contents() if you're already doing sleep_ms(5000) on the previous line!