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updated return-to-zero method to use pwm width of 0

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This commit is contained in:
David Hoelscher 2024-10-20 17:57:50 -05:00
parent 9b8d4803dc
commit 0179f979e5
1 changed files with 12 additions and 50 deletions
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62
platforms/chibios/drivers/audio_pwm_hardware.c
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@ -13,7 +13,6 @@
#include "audio.h"
#include "gpio.h"
#include "timer.h"
#if !defined(AUDIO_PIN)
# error "Audio feature enabled, but no pin selected - see docs/feature_audio under the ARM PWM settings"
@ -32,20 +31,6 @@
extern bool playing_note;
extern bool playing_melody;
extern uint8_t note_timbre;
static bool channel_1_stopped = true;
void channel_1_stop(void);
void channel_1_start(void);
void audio_wait_for_pin(pin_t pin, uint8_t target_state) {
uint16_t wait_limiter_timer;
wait_limiter_timer = timer_read();
while (timer_elapsed(wait_limiter_timer) < 2) {
if (gpio_read_pin(pin) == target_state) {
break;
}
}
}
static PWMConfig pwmCFG = {.frequency = AUDIO_PWM_COUNTER_FREQUENCY, /* PWM clock frequency */
.period = 2,
@ -56,22 +41,19 @@ static float channel_1_frequency = 0.0f;
void channel_1_set_frequency(float freq) {
channel_1_frequency = freq;
pwmcnt_t period;
pwmcnt_t width;
if (freq <= 0.0) {
// a pause/rest has freq=0
channel_1_stop();
return;
period = 2;
width = 0;
} else {
period = (pwmCFG.frequency / freq);
width = PWM_PERCENTAGE_TO_WIDTH(&AUDIO_PWM_DRIVER, (100 - note_timbre) * 100);
}
if (channel_1_stopped) {
channel_1_start();
}
pwmcnt_t period = (pwmCFG.frequency / freq);
chSysLockFromISR();
pwmChangePeriodI(&AUDIO_PWM_DRIVER, period);
pwmEnableChannelI(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1,
// adjust the duty-cycle so that the output is for 'note_timbre' duration HIGH
PWM_PERCENTAGE_TO_WIDTH(&AUDIO_PWM_DRIVER, (100 - note_timbre) * 100));
pwmEnableChannelI(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1, width);
chSysUnlockFromISR();
}
@ -82,35 +64,15 @@ float channel_1_get_frequency(void) {
void channel_1_start(void) {
pwmStop(&AUDIO_PWM_DRIVER);
pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG);
channel_1_stopped = false;
}
void channel_1_stop(void) {
// only certain timers will disable the output (set to zero) when the pwm is stopped.
// to ensure the pin is low (without having changing the pin modes), set the
// frequency to the highest valid value and wait for the pin to be zero
chSysLockFromISR();
pwmChangePeriodI(&AUDIO_PWM_DRIVER, 2);
pwmEnableChannelI(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1,
// adjust the duty-cycle so that the output is for 'note_timbre' duration HIGH
PWM_PERCENTAGE_TO_WIDTH(&AUDIO_PWM_DRIVER, 5000));
chSysUnlockFromISR();
// try stopping now if the pin is currently low
audio_wait_for_pin(AUDIO_PIN,0);
pwmStop(&AUDIO_PWM_DRIVER);
uint16_t wait_limiter_timer;
wait_limiter_timer = timer_read();
// if it isn't actively low, it may have been stopped a little too late, so keep trying
// it should not require very many attempts, so limit to 2ms maximum wait time as a failsafe
while ((gpio_read_pin(AUDIO_PIN) == 1) && (timer_elapsed(wait_limiter_timer) < 2)) {
pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG);
audio_wait_for_pin(AUDIO_PIN,0);
pwmStop(&AUDIO_PWM_DRIVER);
}
channel_1_stopped = true;
pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG);
pwmEnableChannelI(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1, 0);
pwmStop(&AUDIO_PWM_DRIVER);
}
static virtual_timer_t audio_vt;
static void audio_callback(virtual_timer_t *vtp, void *p);