Adafruit_MQTT_Library VS PlatformIO

We are almost there. for adding MQTT to our program, we will again use Adafruit libraries: Adafruit_MQTT and Adafruit_MQTT_Client. There is a great official example that shows the core aspects about how to use the library. After several tries, here is the working version.

Well maintained library from Adafruit https://github.com/adafruit/Adafruit_MQTT_Library

For the ESP32 in read mode, we've successfully developed a project using PlatformIO that accepts the key during build time and stores it in memory.

Check out Zephyr OS and Platform IO. Zephyr is part of the Linux foundation and has similarities to Linux with how it performs hardware abstraction (device tree). Platform IO integrates with other frameworks including mbed and Arduino.

PlatformIO together with avr-stub can be used to do source level debugging but there are some caveats.

Look into https://platformio.org/, it can abstract over a few RTOSes, and can show you which OSes work with which chips/boards.

If the HW looks like it works, you could also try alternate programming software. (e.g. TinyGo or PlatformIO)

You might have better luck with PlatformIO than the Arduino IDE; it's better at automatically choosing the serial port, though I can't say I've used it under Windows.

My other suggestion takes more work but will make your life oh so much better. Professionally I have used and highly recommend. https://platformio.org/ which is free!

Will you be doing embedded Linux? Embedded RTOS? Bare metal? Microcontrollers? SoC (say, FPGA with a hard processor core)?

You can do a lot with QEMU. https://bootlin.com/ has a lot of great, free training material.

https://bootlin.com/doc/training/embedded-linux-qemu/embedde...

is one of my favorites.

Learning to cross-compile, do embedded debugging, the process of booting an embedded system (which varies depending on the answers to the above questions), learning how to read a technical reference for the processor you’re using as well as for peripherals you’re likely to interact with - SPI, i2c, UART, maybe PCIe, are all handy skills. Learn a bit about JTAG, hardware, reading schematics, etc. Even being able solder is helpful.

There may be books (I had a great embedded Linux book when I started) but there are lots of online materials too. Check out https://platformio.org/

There are fun embedded boards and projects for microcontrollers too - micropython on an rpi pico, tinygo, eLua, etc.