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Merge pull request #765 from jerryneedell/jerryn_tick

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modify tick_delay to handle SysTick->VAL rollover
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Scott Shawcroft 2018-04-20 15:40:00 -04:00 committed by GitHub
commit 58ba74194e
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2 changed files with 10 additions and 13 deletions
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5
ports/atmel-samd/common-hal/pulseio/PulseIn.c
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@ -283,12 +283,9 @@ void common_hal_pulseio_pulsein_resume(pulseio_pulsein_obj_t* self,
if (trigger_duration > 0) {
gpio_set_pin_pull_mode(self->pin, GPIO_PULL_OFF);
gpio_set_pin_direction(self->pin, GPIO_DIRECTION_OUT);
common_hal_mcu_disable_interrupts();
gpio_set_pin_level(self->pin, !self->idle_state);
common_hal_mcu_delay_us(trigger_duration);
common_hal_mcu_delay_us((uint32_t)trigger_duration);
gpio_set_pin_level(self->pin, self->idle_state);
common_hal_mcu_enable_interrupts();
}
// Reconfigure the pin and make sure its set to detect the first edge.

18
ports/atmel-samd/tick.c
View File

@ -52,21 +52,21 @@ void SysTick_Handler(void) {
void tick_init() {
uint32_t ticks_per_ms = common_hal_mcu_processor_get_frequency() / 1000;
SysTick_Config(ticks_per_ms);
SysTick_Config(ticks_per_ms-1);
NVIC_EnableIRQ(SysTick_IRQn);
}
void tick_delay(uint32_t us) {
uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
uint32_t us_between_ticks = SysTick->VAL / ticks_per_us;
uint64_t start_ms = ticks_ms;
while (us > 1000) {
while (ticks_ms == start_ms) {}
us -= us_between_ticks;
start_ms = ticks_ms;
us_between_ticks = 1000;
uint32_t us_until_next_tick = SysTick->VAL / ticks_per_us;
uint32_t start_tick;
while (us >= us_until_next_tick) {
start_tick=SysTick->VAL; // wait for SysTick->VAL to RESET
while (SysTick->VAL < start_tick) {}
us -= us_until_next_tick;
us_until_next_tick = 1000;
}
while (SysTick->VAL > ((us_between_ticks - us) * ticks_per_us)) {}
while (SysTick->VAL > ((us_until_next_tick - us) * ticks_per_us)) {}
}
// us counts down!