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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, 5, 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);
+}