diff options
Diffstat (limited to 'platforms/chibios/drivers/audio_pwm_software.c')
| -rw-r--r-- | platforms/chibios/drivers/audio_pwm_software.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/platforms/chibios/drivers/audio_pwm_software.c b/platforms/chibios/drivers/audio_pwm_software.c new file mode 100644 index 0000000000..15c3e98b6a --- /dev/null +++ b/platforms/chibios/drivers/audio_pwm_software.c @@ -0,0 +1,164 @@ +/* Copyright 2020 Jack Humbert + * Copyright 2020 JohSchneider + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +/* +Audio Driver: PWM + +the duty-cycle is always kept at 50%, and the pwm-period is adjusted to match the frequency of a note to be played back. + +this driver uses the chibios-PWM system to produce a square-wave on any given output pin in software +- a pwm callback is used to set/clear the configured pin. + + */ +#include "audio.h" +#include "ch.h" +#include "hal.h" + +#if !defined(AUDIO_PIN) +# error "Audio feature enabled, but no pin selected - see docs/feature_audio under the ARM PWM settings" +#endif +extern bool playing_note; +extern bool playing_melody; +extern uint8_t note_timbre; + +static void pwm_audio_period_callback(PWMDriver *pwmp); +static void pwm_audio_channel_interrupt_callback(PWMDriver *pwmp); + +static PWMConfig pwmCFG = { + .frequency = 100000, /* PWM clock frequency */ + // CHIBIOS-BUG? can't set the initial period to <2, or the pwm (hard or software) takes ~130ms with .frequency=500000 for a pwmChangePeriod to take effect; with no output=silence in the meantime + .period = 2, /* initial PWM period (in ticks) 1S (1/10kHz=0.1mS 0.1ms*10000 ticks=1S) */ + .callback = pwm_audio_period_callback, + .channels = + { + // software-PWM just needs another callback on any channel + {PWM_OUTPUT_ACTIVE_HIGH, pwm_audio_channel_interrupt_callback}, /* channel 0 -> TIMx_CH1 */ + {PWM_OUTPUT_DISABLED, NULL}, /* channel 1 -> TIMx_CH2 */ + {PWM_OUTPUT_DISABLED, NULL}, /* channel 2 -> TIMx_CH3 */ + {PWM_OUTPUT_DISABLED, NULL} /* channel 3 -> TIMx_CH4 */ + }, +}; + +static float channel_1_frequency = 0.0f; +void channel_1_set_frequency(float freq) { + channel_1_frequency = freq; + + if (freq <= 0.0) // a pause/rest has freq=0 + return; + + pwmcnt_t period = (pwmCFG.frequency / freq); + pwmChangePeriod(&AUDIO_PWM_DRIVER, period); + + pwmEnableChannel(&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)); +} + +float channel_1_get_frequency(void) { return channel_1_frequency; } + +void channel_1_start(void) { + pwmStop(&AUDIO_PWM_DRIVER); + pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG); + + pwmEnablePeriodicNotification(&AUDIO_PWM_DRIVER); + pwmEnableChannelNotification(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1); +} + +void channel_1_stop(void) { + pwmStop(&AUDIO_PWM_DRIVER); + + palClearLine(AUDIO_PIN); // leave the line low, after last note was played + +#if defined(AUDIO_PIN_ALT) && defined(AUDIO_PIN_ALT_AS_NEGATIVE) + palClearLine(AUDIO_PIN_ALT); // leave the line low, after last note was played +#endif +} + +// generate a PWM signal on any pin, not necessarily the one connected to the timer +static void pwm_audio_period_callback(PWMDriver *pwmp) { + (void)pwmp; + palClearLine(AUDIO_PIN); + +#if defined(AUDIO_PIN_ALT) && defined(AUDIO_PIN_ALT_AS_NEGATIVE) + palSetLine(AUDIO_PIN_ALT); +#endif +} +static void pwm_audio_channel_interrupt_callback(PWMDriver *pwmp) { + (void)pwmp; + if (channel_1_frequency > 0) { + palSetLine(AUDIO_PIN); // generate a PWM signal on any pin, not necessarily the one connected to the timer +#if defined(AUDIO_PIN_ALT) && defined(AUDIO_PIN_ALT_AS_NEGATIVE) + palClearLine(AUDIO_PIN_ALT); +#endif + } +} + +static void gpt_callback(GPTDriver *gptp); +GPTConfig gptCFG = { + /* a whole note is one beat, which is - per definition in musical_notes.h - set to 64 + the longest note is BREAVE_DOT=128+64=192, the shortest SIXTEENTH=4 + the tempo (which might vary!) is in bpm (beats per minute) + therefore: if the timer ticks away at .frequency = (60*64)Hz, + and the .interval counts from 64 downwards - audio_update_state is + called just often enough to not miss anything + */ + .frequency = 60 * 64, + .callback = gpt_callback, +}; + +void audio_driver_initialize(void) { + pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG); + + palSetLineMode(AUDIO_PIN, PAL_MODE_OUTPUT_PUSHPULL); + palClearLine(AUDIO_PIN); + +#if defined(AUDIO_PIN_ALT) && defined(AUDIO_PIN_ALT_AS_NEGATIVE) + palSetLineMode(AUDIO_PIN_ALT, PAL_MODE_OUTPUT_PUSHPULL); + palClearLine(AUDIO_PIN_ALT); +#endif + + pwmEnablePeriodicNotification(&AUDIO_PWM_DRIVER); // enable pwm callbacks + pwmEnableChannelNotification(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1); + + gptStart(&AUDIO_STATE_TIMER, &gptCFG); +} + +void audio_driver_start(void) { + channel_1_stop(); + channel_1_start(); + + if (playing_note || playing_melody) { + gptStartContinuous(&AUDIO_STATE_TIMER, 64); + } +} + +void audio_driver_stop(void) { + channel_1_stop(); + gptStopTimer(&AUDIO_STATE_TIMER); +} + +/* a regular timer task, that checks the note to be currently played + * and updates the pwm to output that frequency + */ +static void gpt_callback(GPTDriver *gptp) { + float freq; // TODO: freq_alt + + if (audio_update_state()) { + freq = audio_get_processed_frequency(0); // freq_alt would be index=1 + channel_1_set_frequency(freq); + } +} |