Timers, interrupts, watchdog, DMA and clocks

Module goal: use a microcontroller’s main peripherals according to the rules of ISR context and RTOS.

Status: alpha (experimental) · Approximate time: 280 minutes

Every lesson has content, examples you can run on your computer, practice with a solution, a check for understanding, and a lab. The course code runs and has been checked on a computer; the on-board labs are still waiting for a teaching trial.

Lesson	Topic	Time
c-found.m04.l01	GPIO and interrupts	70 min
c-found.m04.l02	Timers and clocks	70 min
c-found.m04.l03	The watchdog	70 min
c-found.m04.l04	DMA	70 min

End-of-module checkpoint

• Read a button with an interrupt and debounce it without blocking, with the ISR doing the least possible work and handing off to a task.
• Calculate a timer’s frequency correctly from a BSP setting (a divider of N divides by N+1), and explain what the clock does to accuracy.
• Explain the correct place to feed the watchdog in an example program, and read a real board’s reset cause.
• Point to where in the SDK’s camera driver the cache must be cleaned before DMA can read, and explain why some buffers are placed in memory that bypasses the cache.