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sensor_sr04: fix shadow counter value issue

This commit is contained in:
King Kévin 2020-12-16 02:37:35 +01:00
parent 25f0235192
commit 0c723fee11
1 changed files with 4 additions and 24 deletions
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28
lib/sensor_sr04.c
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@ -95,6 +95,7 @@ void sensor_sr04_trigger(void)
timer_clear_flag(TIM(SENSOR_SR04_TIMER), TIM_SR_UIF); // clear update flag
timer_clear_flag(TIM(SENSOR_SR04_TIMER), TIM_SR_CCIF(SENSOR_SR04_CHANNEL)); // clear input compare flag
timer_set_counter(TIM(SENSOR_SR04_TIMER), 0); // reset counter
timer_generate_event(TIM(SENSOR_SR04_TIMER), TIM_EGR_UG); // clear shadow register
timer_ic_set_polarity(TIM(SENSOR_SR04_TIMER), TIM_IC(SENSOR_SR04_CHANNEL), TIM_IC_RISING); // capture on incoming echo (rising edge)
sensor_sr04_echo = false; // echo has not been received yet
@ -105,30 +106,6 @@ void sensor_sr04_trigger(void)
// start timer to measure the echo (the rest is done in the ISR)
timer_enable_counter(TIM(SENSOR_SR04_TIMER)); // start timer
/*
while (!gpio_get(GPIO_PORT(SENSOR_SR04_ECHO), GPIO_PIN(SENSOR_SR04_ECHO)) && !timer_get_flag(TIM(SENSOR_SR04_TIMER), TIM_SR_UIF)); // wait for echo
if (timer_get_flag(TIM(SENSOR_SR04_TIMER), TIM_SR_UIF)) { // timeout reached
// timer is already disabled
return 0; // did not get any echo
}
// the echo should have been received, measure it
timer_set_counter(TIM(SENSOR_SR04_TIMER), 0); // reset counter to measure echo
while (gpio_get(GPIO_PORT(SENSOR_SR04_ECHO), GPIO_PIN(SENSOR_SR04_ECHO)) && !timer_get_flag(TIM(SENSOR_SR04_TIMER), TIM_SR_UIF)); // wait for end of echo
if (timer_get_flag(TIM(SENSOR_SR04_TIMER), TIM_SR_UIF)) { // timeout reached
// timer is already disabled
return UINT16_MAX; // object out of range
}
// convert to distance
const uint16_t count = timer_get_counter(TIM(SENSOR_SR04_TIMER)); // get measured time
timer_disable_counter(TIM(SENSOR_SR04_TIMER)); // stop timer (just to be clean)
// calculate distance in mm
return (count * (TIM_PSC(TIM(SENSOR_SR04_TIMER)) + 1) * (343 / 2)) / (rcc_ahb_frequency / 1000);
// TODO use input capture, and interrupts
*/
}
/** interrupt service routine called for timer */
@ -144,8 +121,11 @@ void TIM_ISR(SENSOR_SR04_TIMER)(void)
} else if (timer_get_flag(TIM(SENSOR_SR04_TIMER), TIM_SR_CCIF(SENSOR_SR04_CHANNEL))) { // edge detected on input capture
timer_clear_flag(TIM(SENSOR_SR04_TIMER), TIM_SR_CCIF(SENSOR_SR04_CHANNEL)); // clear input compare flag
if (!sensor_sr04_echo) { // echo is incoming
timer_disable_counter(TIM(SENSOR_SR04_TIMER)); // disable while reconfiguring
timer_set_counter(TIM(SENSOR_SR04_TIMER), 0); // reset timer counter
timer_generate_event(TIM(SENSOR_SR04_TIMER), TIM_EGR_UG); // clear shadow register
timer_ic_set_polarity(TIM(SENSOR_SR04_TIMER), TIM_IC(SENSOR_SR04_CHANNEL), TIM_IC_FALLING); // capture on end of echo (falling edge)
timer_enable_counter(TIM(SENSOR_SR04_TIMER)); // re-enable
sensor_sr04_echo = true; // remember echo is incoming
} else { // end of echo
timer_disable_counter(TIM(SENSOR_SR04_TIMER)); // disable counter now that measurement is complete