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