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qmk_firmware/platforms/chibios/drivers/audio_dac_basic.c

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/* Copyright 2016-2020 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/>.
*/
#include "audio.h"
#include "ch.h"
#include "hal.h"
/*
Audio Driver: DAC
which utilizes both channels of the DAC unit many STM32 are equipped with to output a modulated square-wave, from precomputed samples stored in a buffer, which is passed to the hardware through DMA
this driver can either be used to drive to separate speakers, wired to A4+Gnd and A5+Gnd, which allows two tones to be played simultaneously
OR
one speaker wired to A4+A5 with the AUDIO_PIN_ALT_AS_NEGATIVE define set - see docs/feature_audio
*/
#if !defined(AUDIO_PIN)
# pragma message "Audio feature enabled, but no suitable pin selected as AUDIO_PIN - see docs/feature_audio under 'ARM (DAC basic)' for available options."
// TODO: make this an 'error' instead; go through a breaking change, and add AUDIO_PIN A5 to all keyboards currently using AUDIO on STM32 based boards? - for now: set the define here
# define AUDIO_PIN A5
#endif
// check configuration for ONE speaker, connected to both DAC pins
#if defined(AUDIO_PIN_ALT_AS_NEGATIVE) && !defined(AUDIO_PIN_ALT)
# error "Audio feature: AUDIO_PIN_ALT_AS_NEGATIVE set, but no pin configured as AUDIO_PIN_ALT"
#endif
#ifndef AUDIO_PIN_ALT
// no ALT pin defined is valid, but the c-ifs below need some value set
# define AUDIO_PIN_ALT -1
#endif
#if !defined(AUDIO_STATE_TIMER)
# define AUDIO_STATE_TIMER GPTD8
#endif
// square-wave
static const dacsample_t dac_buffer_1[AUDIO_DAC_BUFFER_SIZE] = {
// First half is max, second half is 0
[0 ... AUDIO_DAC_BUFFER_SIZE / 2 - 1] = AUDIO_DAC_SAMPLE_MAX,
[AUDIO_DAC_BUFFER_SIZE / 2 ... AUDIO_DAC_BUFFER_SIZE - 1] = 0,
};
// square-wave
static const dacsample_t dac_buffer_2[AUDIO_DAC_BUFFER_SIZE] = {
// opposite of dac_buffer above
[0 ... AUDIO_DAC_BUFFER_SIZE / 2 - 1] = 0,
[AUDIO_DAC_BUFFER_SIZE / 2 ... AUDIO_DAC_BUFFER_SIZE - 1] = AUDIO_DAC_SAMPLE_MAX,
};
GPTConfig gpt6cfg1 = {.frequency = AUDIO_DAC_SAMPLE_RATE,
.callback = NULL,
.cr2 = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event. */
.dier = 0U};
GPTConfig gpt7cfg1 = {.frequency = AUDIO_DAC_SAMPLE_RATE,
.callback = NULL,
.cr2 = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event. */
.dier = 0U};
static void gpt_audio_state_cb(GPTDriver *gptp);
GPTConfig gptStateUpdateCfg = {.frequency = 10,
.callback = gpt_audio_state_cb,
.cr2 = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event. */
.dier = 0U};
static const DACConfig dac_conf_ch1 = {.init = AUDIO_DAC_OFF_VALUE, .datamode = DAC_DHRM_12BIT_RIGHT};
static const DACConfig dac_conf_ch2 = {.init = AUDIO_DAC_OFF_VALUE, .datamode = DAC_DHRM_12BIT_RIGHT};
/**
* @note The DAC_TRG(0) here selects the Timer 6 TRGO event, which is triggered
* on the rising edge after 3 APB1 clock cycles, causing our gpt6cfg1.frequency
* to be a third of what we expect.
*
* Here are all the values for DAC_TRG (TSEL in the ref manual)
* TIM15_TRGO 0b011
* TIM2_TRGO 0b100
* TIM3_TRGO 0b001
* TIM6_TRGO 0b000
* TIM7_TRGO 0b010
* EXTI9 0b110
* SWTRIG 0b111
*/
static const DACConversionGroup dac_conv_grp_ch1 = {.num_channels = 1U, .trigger = DAC_TRG(0b000)};
static const DACConversionGroup dac_conv_grp_ch2 = {.num_channels = 1U, .trigger = DAC_TRG(0b010)};
void channel_1_start(void) {
gptStart(&GPTD6, &gpt6cfg1);
gptStartContinuous(&GPTD6, 2U);
palSetPadMode(GPIOA, 4, PAL_MODE_INPUT_ANALOG);
}
void channel_1_stop(void) {
gptStopTimer(&GPTD6);
palSetPadMode(GPIOA, 4, PAL_MODE_OUTPUT_PUSHPULL);
palSetPad(GPIOA, 4);
}
static float channel_1_frequency = 0.0f;
void channel_1_set_frequency(float freq) {
channel_1_frequency = freq;
channel_1_stop();
if (freq <= 0.0) // a pause/rest has freq=0
return;
gpt6cfg1.frequency = 2 * freq * AUDIO_DAC_BUFFER_SIZE;
channel_1_start();
}
float channel_1_get_frequency(void) {
return channel_1_frequency;
}
void channel_2_start(void) {
gptStart(&GPTD7, &gpt7cfg1);
gptStartContinuous(&GPTD7, 2U);
palSetPadMode(GPIOA, 5, PAL_MODE_INPUT_ANALOG);
}
void channel_2_stop(void) {
gptStopTimer(&GPTD7);
palSetPadMode(GPIOA, 5, PAL_MODE_OUTPUT_PUSHPULL);
palSetPad(GPIOA, 5);
}
static float channel_2_frequency = 0.0f;
void channel_2_set_frequency(float freq) {
channel_2_frequency = freq;
channel_2_stop();
if (freq <= 0.0) // a pause/rest has freq=0
return;
gpt7cfg1.frequency = 2 * freq * AUDIO_DAC_BUFFER_SIZE;
channel_2_start();
}
float channel_2_get_frequency(void) {
return channel_2_frequency;
}
static void gpt_audio_state_cb(GPTDriver *gptp) {
if (audio_update_state()) {
#if defined(AUDIO_PIN_ALT_AS_NEGATIVE)
// one piezo/speaker connected to both audio pins, the generated square-waves are inverted
channel_1_set_frequency(audio_get_processed_frequency(0));
channel_2_set_frequency(audio_get_processed_frequency(0));
#else // two separate audio outputs/speakers
// primary speaker on A4, optional secondary on A5
if (AUDIO_PIN == A4) {
channel_1_set_frequency(audio_get_processed_frequency(0));
if (AUDIO_PIN_ALT == A5) {
if (audio_get_number_of_active_tones() > 1) {
channel_2_set_frequency(audio_get_processed_frequency(1));
} else {
channel_2_stop();
}
}
}
// primary speaker on A5, optional secondary on A4
if (AUDIO_PIN == A5) {
channel_2_set_frequency(audio_get_processed_frequency(0));
if (AUDIO_PIN_ALT == A4) {
if (audio_get_number_of_active_tones() > 1) {
channel_1_set_frequency(audio_get_processed_frequency(1));
} else {
channel_1_stop();
}
}
}
#endif
}
}
void audio_driver_initialize() {
if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
palSetPadMode(GPIOA, 4, PAL_MODE_INPUT_ANALOG);
dacStart(&DACD1, &dac_conf_ch1);
// initial setup of the dac-triggering timer is still required, even
// though it gets reconfigured and restarted later on
gptStart(&GPTD6, &gpt6cfg1);
}
if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
palSetPadMode(GPIOA, 5, PAL_MODE_INPUT_ANALOG);
dacStart(&DACD2, &dac_conf_ch2);
gptStart(&GPTD7, &gpt7cfg1);
}
/* enable the output buffer, to directly drive external loads with no additional circuitry
*
* see: AN4566 Application note: Extending the DAC performance of STM32 microcontrollers
* Note: Buffer-Off bit -> has to be set 0 to enable the output buffer
* Note: enabling the output buffer imparts an additional dc-offset of a couple mV
*
* this is done here, reaching directly into the stm32 registers since chibios has not implemented BOFF handling yet
* (see: chibios/os/hal/ports/STM32/todo.txt '- BOFF handling in DACv1.'
*/
DACD1.params->dac->CR &= ~DAC_CR_BOFF1;
DACD2.params->dac->CR &= ~DAC_CR_BOFF2;
// start state-updater
gptStart(&AUDIO_STATE_TIMER, &gptStateUpdateCfg);
}
void audio_driver_stop(void) {
if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
gptStopTimer(&GPTD6);
// stop the ongoing conversion and put the output in a known state
dacStopConversion(&DACD1);
dacPutChannelX(&DACD1, 0, AUDIO_DAC_OFF_VALUE);
}
if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
gptStopTimer(&GPTD7);
dacStopConversion(&DACD2);
dacPutChannelX(&DACD2, 0, AUDIO_DAC_OFF_VALUE);
}
gptStopTimer(&AUDIO_STATE_TIMER);
}
void audio_driver_start(void) {
if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) {
dacStartConversion(&DACD1, &dac_conv_grp_ch1, (dacsample_t *)dac_buffer_1, AUDIO_DAC_BUFFER_SIZE);
}
if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) {
dacStartConversion(&DACD2, &dac_conv_grp_ch2, (dacsample_t *)dac_buffer_2, AUDIO_DAC_BUFFER_SIZE);
}
gptStartContinuous(&AUDIO_STATE_TIMER, 2U);
}
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