Test that ticker_fire_interrupt causes the interrupt to get fired immediately.

Given ticker is available. When ticker_fire_interrupt is called. Then ticker interrupt is triggered.

Test that the ticker is operating at the frequency it specifies.

Given ticker is available. When ticker specifies its frequency. Then the specified frequency is valid.

Test that the ticker increments by one on each tick.

We have the following assumption for the timer clock frequency:

NOTE: high freq ticker: 250 KHz (1 tick per 4 us) - 8 Mhz (1 tick per 1/8 us) low power ticker: 8 KHz (1 tick per 125 us) - 64 KHz (1 tick per ~15.6 us)

Lowest CPU speed is 16 MHz (1 tick per 1/16 us).

For the boards with ticker clock freq less than or equal to 250 KHz we will try to prove that ticker is incremented by one straightforward by reading ticker count value in the loop in order to detect a single ticker value update (hopefully by one). For faster tickers we need to prove this indirectly using additional count_ticks() function which returns number of ticks needed to perform N cycles of the empty while loop. For the same number of cycles function result should be the same with accuracy +/- 1 tick. After the first test we will call count_ticks again with number of cycles equal N, N+1, N+2, ... until we get other ticks result.

Given ticker is available. When ticker is initialised. Then ticker counter is incremented by one.

Test that ticker frequency is non-zero and counter is at least 8 bits.

Given ticker is available. When ticker information data is obtained. Then ticker information indicate that frequency is non-zero and counter is at least 8 bits.

Test that ticker_init can be called multiple times and ticker_init resets the internal count and disables the ticker interrupt.

Given ticker is initialised and interrupt is set. When ticker is re-initialised. Then ticker keeps counting and disables the ticker interrupt.

Test that ticker interrupt fires only when the ticker counter increments to the value set by ticker_set_interrupt.

Given ticker is available, initialised. When ticker interrupt is set. Then ticker interrupt fires at the valid time.

Test that the ticker correctly handles overflow.

Note that for high frequency timers we will only prove that ticker counter rollovers and continue counting (it is not possible to prove in deterministic way that after rollover next value is 0).

Given ticker is available. When ticker has overflows. Then ticker continues counting from the beginning and interrupt scheduling works.

Test that ticker interrupt is not triggered when ticker_set_interrupt is called with a time from the past.

Given ticker is available, initialised. When ticker interrupt is set to the time in the past. Then ticker interrupt is not triggered.

Test that ticker can be rescheduled repeatedly before the handler has been called.

Given ticker is available, initialised. When ticker interrupt is set and then rescheduled (interrupt time is modified). Then ticker interrupt is triggered according the rescheduled time.

Test that common ticker functions complete with the required amount of time.

Given ticker is available. When ticker_read, ticker_clear_interrupt, ticker_set_interrupt, ticker_fire_interrupt or ticker_disable_interrupt function is called. Then its execution is not longer than 20 us.