diff options
Diffstat (limited to 'platforms/chibios/drivers/audio_dac_basic.c')
| -rw-r--r-- | platforms/chibios/drivers/audio_dac_basic.c | 245 | 
1 files changed, 245 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..fac6513506 --- /dev/null +++ b/platforms/chibios/drivers/audio_dac_basic.c @@ -0,0 +1,245 @@ +/* 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); +} | 
