diff options
Diffstat (limited to 'platforms/chibios/drivers/audio_dac_basic.c')
| -rw-r--r-- | platforms/chibios/drivers/audio_dac_basic.c | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/platforms/chibios/drivers/audio_dac_basic.c b/platforms/chibios/drivers/audio_dac_basic.c new file mode 100644 index 0000000000..64439a1e3c --- /dev/null +++ b/platforms/chibios/drivers/audio_dac_basic.c @@ -0,0 +1,249 @@ +/* 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); +} |