4.5 The microcontroller

I declare: solidlikelyshaky

1. Blink an LED without a high-level library, by writing to the pin’s registers.
2. Read a button with bounce under control, by software or by RC.
3. Produce a hardware PWM at a chosen frequency and duty cycle, and measure it.
4. Use an external interrupt and a timer interrupt, and explain what you never do inside them.
5. Read a sensor, convert to a physical unit, and send it over UART to the computer.
6. Structure a program as a state machine, without blocking waits (from a millisecond counter), and arm the watchdog.
7. Keep a setting in non-volatile memory and read it back at start-up, counting write cycles.
8. Diagnosis: a program that "crashes at random", stack overflow, shared variable without volatile or badly fed watchdog.