- Uninitialized exception vectors (you know, for the ones that “will never be reached”)
- Say it with me: Global variables. Especially ones shared between ISRs and tasks (or foreground loops) without protection.
- Failure to use “volatile” where necessary.
- Having routines that DisableInterrupts() and then EnableInterrupts() paired up. Got that? Not RestoreInterrupts(), but ENABLE. Yeah, nesting.
- No GPIOs to toggle when testing.
- No testpoints on board.
- No LEDs or serial port for viewing run-time system status.
- No measurement of how busy/idle the CPU is.
- Use of inline assembly for all but the most dire of cases. Write a quick callout.
- Using for (i = 0; i < 1000; i++) { } to “delay a bit”. Yeah, that’s not gonna bite you in a hundred different ways….
- Not using const everywhere possible to preserve RAM and reduce boot time (no copying / init of variables)
I’ve got a ton more but that should get us started….