Phase 3 · Professional

Goal: work the way a firmware team works. Move to an industry-standard STM32, structure code in layers, test it on your laptop, use an RTOS on purpose, and debug with real instruments.

Four modules, roughly 8 to 12 weeks. This phase produces the project you talk about in interviews.

Module	You will be able to	Time
8. Stepping up to STM32	Navigate ST's reference manual, datasheet, and programming manual; build with CubeIDE or CMake; debug over ST-LINK.	1 to 2 weeks
9. Firmware architecture and testing	Split code into hardware, HAL, driver, and application layers; write state machines and ring buffers; unit test on the host; follow a coding standard.	3 to 4 weeks
10. Real time and RTOS	Explain what "real time" means, choose bare metal vs RTOS vs Linux, and use FreeRTOS or Zephyr tasks, queues, and mutexes without deadlocking.	2 to 3 weeks
11. Debugging and measurement	Read a HardFault, use GDB beyond breakpoints, decode buses on a logic analyzer, and probe signals on an oscilloscope.	2 weeks

Can I skip anything? No. If you are a working engineer, this is where you start reading closely.