// delay for given number of microseconds
void sys_tick_udelay(uint32_t usec) {
if (query_irq() == IRQ_STATE_ENABLED) {
// IRQs enabled, so can use systick counter to do the delay
uint32_t start = sys_tick_get_microseconds();
while (sys_tick_get_microseconds() - start < usec) {
}
} else {
// IRQs disabled, so need to use a busy loop for the delay
// sys freq is always a multiple of 2MHz, so division here won't lose precision
const uint32_t ucount = HAL_RCC_GetSysClockFreq() / 2000000 * usec / 2;
for (uint32_t count = 0; ++count <= ucount;) {
}
}
}
STATIC mp_obj_t time_ticks_us(void) {
// We want to "cast" the 32 bit unsigned into a 30-bit small-int
return MP_OBJ_NEW_SMALL_INT(sys_tick_get_microseconds() & MP_SMALL_INT_POSITIVE_MASK);
}
/// \function elapsed_micros(start)
/// Returns the number of microseconds which have elapsed since `start`.
///
/// This function takes care of counter wrap, and always returns a positive
/// number. This means it can be used to measure periods upto about 17.8 minutes.
///
/// Example:
/// start = pyb.micros()
/// while pyb.elapsed_micros(start) < 1000:
/// # Perform some operation
STATIC mp_obj_t pyb_elapsed_micros(mp_obj_t start) {
uint32_t startMicros = mp_obj_get_int(start);
uint32_t currMicros = sys_tick_get_microseconds();
return MP_OBJ_NEW_SMALL_INT((currMicros - startMicros) & 0x3fffffff);
}
/// \function micros()
/// Returns the number of microseconds since the board was last reset.
///
/// The result is always a micropython smallint (31-bit signed number), so
/// after 2^30 microseconds (about 17.8 minutes) this will start to return
/// negative numbers.
STATIC mp_obj_t pyb_micros(void) {
// We want to "cast" the 32 bit unsigned into a small-int. This means
// copying the MSB down 1 bit (extending the sign down), which is
// equivalent to just using the MP_OBJ_NEW_SMALL_INT macro.
return MP_OBJ_NEW_SMALL_INT(sys_tick_get_microseconds());
}
STATIC mp_obj_t time_ticks_us(void) {
return MP_OBJ_NEW_SMALL_INT(sys_tick_get_microseconds() & MP_SMALL_INT_POSITIVE_MASK);
}
