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@@ -1,29 +1,15 @@
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-/* Copyright 2020 Jack Humbert
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- * Copyright 2020 JohSchneider
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- *
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- * This program is free software: you can redistribute it and/or modify
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- * it under the terms of the GNU General Public License as published by
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- * the Free Software Foundation, either version 2 of the License, or
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- * (at your option) any later version.
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- *
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- * This program is distributed in the hope that it will be useful,
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- * but WITHOUT ANY WARRANTY; without even the implied warranty of
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- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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- * GNU General Public License for more details.
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- *
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- * You should have received a copy of the GNU General Public License
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- * along with this program. If not, see <http://www.gnu.org/licenses/>.
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- */
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-
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-/*
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-Audio Driver: PWM
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-
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-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.
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-
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-this driver uses the chibios-PWM system to produce a square-wave on specific output pins that are connected to the PWM hardware.
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-The hardware directly toggles the pin via its alternate function. see your MCUs data-sheet for which pin can be driven by what timer - looking for TIMx_CHy and the corresponding alternate function.
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-
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- */
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+// Copyright 2022 Stefan Kerkmann
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+// Copyright 2020 Jack Humbert
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+// Copyright 2020 JohSchneider
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+// SPDX-License-Identifier: GPL-2.0-or-later
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+
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+// Audio Driver: PWM the duty-cycle is always kept at 50%, and the pwm-period is
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+// adjusted to match the frequency of a note to be played back. This driver uses
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+// the chibios-PWM system to produce a square-wave on specific output pins that
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+// are connected to the PWM hardware. The hardware directly toggles the pin via
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+// its alternate function. see your MCUs data-sheet for which pin can be driven
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+// by what timer - looking for TIMx_CHy and the corresponding alternate
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+// function.
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#include "audio.h"
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#include "ch.h"
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@@ -33,53 +19,36 @@ The hardware directly toggles the pin via its alternate function. see your MCUs
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# error "Audio feature enabled, but no pin selected - see docs/feature_audio under the ARM PWM settings"
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#endif
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+#if !defined(AUDIO_PWM_COUNTER_FREQUENCY)
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+# define AUDIO_PWM_COUNTER_FREQUENCY 100000
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+#endif
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+
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extern bool playing_note;
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extern bool playing_melody;
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extern uint8_t note_timbre;
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-static PWMConfig pwmCFG = {
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- .frequency = 100000, /* PWM clock frequency */
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- // 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
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- .period = 2, /* initial PWM period (in ticks) 1S (1/10kHz=0.1mS 0.1ms*10000 ticks=1S) */
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- .callback = NULL, /* no callback, the hardware directly toggles the pin */
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- .channels =
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- {
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-#if AUDIO_PWM_CHANNEL == 4
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- {PWM_OUTPUT_DISABLED, NULL}, /* channel 0 -> TIMx_CH1 */
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- {PWM_OUTPUT_DISABLED, NULL}, /* channel 1 -> TIMx_CH2 */
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- {PWM_OUTPUT_DISABLED, NULL}, /* channel 2 -> TIMx_CH3 */
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- {PWM_OUTPUT_ACTIVE_HIGH, NULL} /* channel 3 -> TIMx_CH4 */
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-#elif AUDIO_PWM_CHANNEL == 3
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- {PWM_OUTPUT_DISABLED, NULL},
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- {PWM_OUTPUT_DISABLED, NULL},
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- {PWM_OUTPUT_ACTIVE_HIGH, NULL}, /* TIMx_CH3 */
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- {PWM_OUTPUT_DISABLED, NULL}
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-#elif AUDIO_PWM_CHANNEL == 2
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- {PWM_OUTPUT_DISABLED, NULL},
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- {PWM_OUTPUT_ACTIVE_HIGH, NULL}, /* TIMx_CH2 */
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- {PWM_OUTPUT_DISABLED, NULL},
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- {PWM_OUTPUT_DISABLED, NULL}
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-#else /*fallback to CH1 */
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- {PWM_OUTPUT_ACTIVE_HIGH, NULL}, /* TIMx_CH1 */
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- {PWM_OUTPUT_DISABLED, NULL},
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- {PWM_OUTPUT_DISABLED, NULL},
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- {PWM_OUTPUT_DISABLED, NULL}
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-#endif
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- },
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-};
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+static PWMConfig pwmCFG = {.frequency = AUDIO_PWM_COUNTER_FREQUENCY, /* PWM clock frequency */
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+ .period = 2,
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+ .callback = NULL,
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+ .channels = {[(AUDIO_PWM_CHANNEL - 1)] = {.mode = PWM_OUTPUT_ACTIVE_HIGH, .callback = NULL}}};
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static float channel_1_frequency = 0.0f;
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-void channel_1_set_frequency(float freq) {
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+
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+void channel_1_set_frequency(float freq) {
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channel_1_frequency = freq;
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- if (freq <= 0.0) // a pause/rest has freq=0
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+ if (freq <= 0.0) {
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+ // a pause/rest has freq=0
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return;
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+ }
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pwmcnt_t period = (pwmCFG.frequency / freq);
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- pwmChangePeriod(&AUDIO_PWM_DRIVER, period);
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- pwmEnableChannel(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1,
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- // adjust the duty-cycle so that the output is for 'note_timbre' duration HIGH
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- PWM_PERCENTAGE_TO_WIDTH(&AUDIO_PWM_DRIVER, (100 - note_timbre) * 100));
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+ chSysLockFromISR();
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+ pwmChangePeriodI(&AUDIO_PWM_DRIVER, period);
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+ pwmEnableChannelI(&AUDIO_PWM_DRIVER, AUDIO_PWM_CHANNEL - 1,
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+ // adjust the duty-cycle so that the output is for 'note_timbre' duration HIGH
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+ PWM_PERCENTAGE_TO_WIDTH(&AUDIO_PWM_DRIVER, (100 - note_timbre) * 100));
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+ chSysUnlockFromISR();
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}
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float channel_1_get_frequency(void) {
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@@ -95,54 +64,53 @@ void channel_1_stop(void) {
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pwmStop(&AUDIO_PWM_DRIVER);
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}
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-static void gpt_callback(GPTDriver *gptp);
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-GPTConfig gptCFG = {
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- /* a whole note is one beat, which is - per definition in musical_notes.h - set to 64
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- the longest note is BREAVE_DOT=128+64=192, the shortest SIXTEENTH=4
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- the tempo (which might vary!) is in bpm (beats per minute)
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- therefore: if the timer ticks away at .frequency = (60*64)Hz,
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- and the .interval counts from 64 downwards - audio_update_state is
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- called just often enough to not miss any notes
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- */
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- .frequency = 60 * 64,
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- .callback = gpt_callback,
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-};
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+static virtual_timer_t audio_vt;
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+static void audio_callback(virtual_timer_t *vtp, void *p);
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+
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+// a regular timer task, that checks the note to be currently played and updates
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+// the pwm to output that frequency.
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+static void audio_callback(virtual_timer_t *vtp, void *p) {
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+ float freq; // TODO: freq_alt
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+
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+ if (audio_update_state()) {
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+ freq = audio_get_processed_frequency(0); // freq_alt would be index=1
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+ channel_1_set_frequency(freq);
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+ }
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+
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+ chSysLockFromISR();
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+ chVTSetI(&audio_vt, TIME_MS2I(16), audio_callback, NULL);
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+ chSysUnlockFromISR();
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+}
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void audio_driver_initialize(void) {
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pwmStart(&AUDIO_PWM_DRIVER, &pwmCFG);
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// connect the AUDIO_PIN to the PWM hardware
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-#if defined(USE_GPIOV1) // STM32F103C8
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- palSetLineMode(AUDIO_PIN, PAL_MODE_ALTERNATE_PUSHPULL);
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+#if defined(USE_GPIOV1) // STM32F103C8, RP2040
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+ palSetLineMode(AUDIO_PIN, AUDIO_PWM_PAL_MODE);
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#else // GPIOv2 (or GPIOv3 for f4xx, which is the same/compatible at this command)
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palSetLineMode(AUDIO_PIN, PAL_MODE_ALTERNATE(AUDIO_PWM_PAL_MODE));
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#endif
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- gptStart(&AUDIO_STATE_TIMER, &gptCFG);
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+ chVTObjectInit(&audio_vt);
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}
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void audio_driver_start(void) {
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channel_1_stop();
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channel_1_start();
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- if (playing_note || playing_melody) {
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- gptStartContinuous(&AUDIO_STATE_TIMER, 64);
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+ if ((playing_note || playing_melody) && !chVTIsArmed(&audio_vt)) {
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+ // a whole note is one beat, which is - per definition in
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+ // musical_notes.h - set to 64 the longest note is
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+ // BREAVE_DOT=128+64=192, the shortest SIXTEENTH=4 the tempo (which
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+ // might vary!) is in bpm (beats per minute) therefore: if the timer
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+ // ticks away at 64Hz (~16.6ms) audio_update_state is called just often
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+ // enough to not miss any notes
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+ chVTSet(&audio_vt, TIME_MS2I(16), audio_callback, NULL);
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}
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}
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void audio_driver_stop(void) {
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channel_1_stop();
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- gptStopTimer(&AUDIO_STATE_TIMER);
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-}
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-
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-/* a regular timer task, that checks the note to be currently played
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- * and updates the pwm to output that frequency
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- */
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-static void gpt_callback(GPTDriver *gptp) {
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- float freq; // TODO: freq_alt
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-
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- if (audio_update_state()) {
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- freq = audio_get_processed_frequency(0); // freq_alt would be index=1
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- channel_1_set_frequency(freq);
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- }
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+ chVTReset(&audio_vt);
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}
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Stefan Kerkmann