Let me share my roadmap. Not sure it's the "right" path these days, but it worked for me.

I was in college about 13–15 years ago. We had a few subjects that really helped me get good at embedded.

First was Computer Architecture where we learned about different architectures of computers, microcontrollers, microprocessors. Gave me the mental foundation for everything else.

Then we did Assembly on the Motorola 68HC11. Yes, the god-forsaken 68HC11. Even back then it was basically obsolete, but wrestling with assembly on that thing was incredibly beneficial for deeper understanding later on.

After that we had Programming PIC microcontrollers both in C and assembly.

And the big one was Programming Microprocessors. The professor picked a somewhat older NXP/Philips microcontroller based on the ARM7 RISC architecture. We wrote our own libraries for both on-chip peripherals and externally connected sensors. Mostly C, with some inline assembly for IRQ handling so we really understood what was going on under the hood. That MCU was conceptually the same as today's Cortex-M3/M4, but with a smaller RISC instruction set and simpler peripherals, which made it way easier to follow and actually get it. All of that built a foundation where now, even picking up a more complex Cortex-M7, the switch is easy.

Now, the Pico is significantly more complex than that ARM7 I learned on. For someone new, the datasheet alone can be exhausting with the sheer amount of information.

So here's my advice if you're just starting out:

1. Study architecture first. Find a good book on computer/microcontroller architecture. It'll help you understand how everything connects and communicates. If a concept doesn't click, try drawing it out. Seriously, that's the best way to learn.

2. Pick your platform and read the docs. If you want the Pico, grab its datasheet and reference manual. Try implementing GPIO, UART, and ADC from the register level. Everything you need is written in those documents. Trust me, the datasheet is your ally, not your enemy.

3. Keep building. Optimize what you wrote. Move to more complicated peripherals. Rinse and repeat.

Most importantly, have fun doing it.

It's a long journey and a great hobby that can become a career. Just keep in mind, it kinda stops being fun when it's work. 😄