diff options
Diffstat (limited to 'platforms/chibios/drivers/audio_dac_additive.c')
| -rw-r--r-- | platforms/chibios/drivers/audio_dac_additive.c | 335 |
1 files changed, 335 insertions, 0 deletions
diff --git a/platforms/chibios/drivers/audio_dac_additive.c b/platforms/chibios/drivers/audio_dac_additive.c new file mode 100644 index 0000000000..db304adb87 --- /dev/null +++ b/platforms/chibios/drivers/audio_dac_additive.c @@ -0,0 +1,335 @@ +/* Copyright 2016-2019 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 the dac unit many STM32 are equipped with, to output a modulated waveform from samples stored in the dac_buffer_* array who are passed to the hardware through DMA + + it is also possible to have a custom sample-LUT by implementing/overriding 'dac_value_generate' + + this driver allows for multiple simultaneous tones to be played through one single channel by doing additive wave-synthesis +*/ + +#if !defined(AUDIO_PIN) +# error "Audio feature enabled, but no suitable pin selected as AUDIO_PIN - see docs/feature_audio under 'ARM (DAC additive)' for available options." +#endif +#if defined(AUDIO_PIN_ALT) && !defined(AUDIO_PIN_ALT_AS_NEGATIVE) +# pragma message "Audio feature: AUDIO_PIN_ALT set, but not AUDIO_PIN_ALT_AS_NEGATIVE - pin will be left unused; audio might still work though." +#endif + +#if !defined(AUDIO_PIN_ALT) +// no ALT pin defined is valid, but the c-ifs below need some value set +# define AUDIO_PIN_ALT PAL_NOLINE +#endif + +#if !defined(AUDIO_DAC_SAMPLE_WAVEFORM_SINE) && !defined(AUDIO_DAC_SAMPLE_WAVEFORM_TRIANGLE) && !defined(AUDIO_DAC_SAMPLE_WAVEFORM_SQUARE) && !defined(AUDIO_DAC_SAMPLE_WAVEFORM_TRAPEZOID) +# define AUDIO_DAC_SAMPLE_WAVEFORM_SINE +#endif + +#ifdef AUDIO_DAC_SAMPLE_WAVEFORM_SINE +/* one full sine wave over [0,2*pi], but shifted up one amplitude and left pi/4; for the samples to start at 0 + */ +static const dacsample_t dac_buffer_sine[AUDIO_DAC_BUFFER_SIZE] = { + // 256 values, max 4095 + 0x0, 0x1, 0x2, 0x6, 0xa, 0xf, 0x16, 0x1e, 0x27, 0x32, 0x3d, 0x4a, 0x58, 0x67, 0x78, 0x89, 0x9c, 0xb0, 0xc5, 0xdb, 0xf2, 0x10a, 0x123, 0x13e, 0x159, 0x175, 0x193, 0x1b1, 0x1d1, 0x1f1, 0x212, 0x235, 0x258, 0x27c, 0x2a0, 0x2c6, 0x2ed, 0x314, 0x33c, 0x365, 0x38e, 0x3b8, 0x3e3, 0x40e, 0x43a, 0x467, 0x494, 0x4c2, 0x4f0, 0x51f, 0x54e, 0x57d, 0x5ad, 0x5dd, 0x60e, 0x63f, 0x670, 0x6a1, 0x6d3, 0x705, 0x737, 0x769, 0x79b, 0x7cd, 0x800, 0x832, 0x864, 0x896, 0x8c8, 0x8fa, 0x92c, 0x95e, 0x98f, 0x9c0, 0x9f1, 0xa22, 0xa52, 0xa82, 0xab1, 0xae0, 0xb0f, 0xb3d, 0xb6b, 0xb98, 0xbc5, 0xbf1, 0xc1c, 0xc47, 0xc71, 0xc9a, 0xcc3, 0xceb, 0xd12, 0xd39, 0xd5f, 0xd83, 0xda7, 0xdca, 0xded, 0xe0e, 0xe2e, 0xe4e, 0xe6c, 0xe8a, 0xea6, 0xec1, 0xedc, 0xef5, 0xf0d, 0xf24, 0xf3a, 0xf4f, 0xf63, 0xf76, 0xf87, 0xf98, 0xfa7, 0xfb5, 0xfc2, 0xfcd, 0xfd8, 0xfe1, 0xfe9, 0xff0, 0xff5, 0xff9, 0xffd, 0xffe, + 0xfff, 0xffe, 0xffd, 0xff9, 0xff5, 0xff0, 0xfe9, 0xfe1, 0xfd8, 0xfcd, 0xfc2, 0xfb5, 0xfa7, 0xf98, 0xf87, 0xf76, 0xf63, 0xf4f, 0xf3a, 0xf24, 0xf0d, 0xef5, 0xedc, 0xec1, 0xea6, 0xe8a, 0xe6c, 0xe4e, 0xe2e, 0xe0e, 0xded, 0xdca, 0xda7, 0xd83, 0xd5f, 0xd39, 0xd12, 0xceb, 0xcc3, 0xc9a, 0xc71, 0xc47, 0xc1c, 0xbf1, 0xbc5, 0xb98, 0xb6b, 0xb3d, 0xb0f, 0xae0, 0xab1, 0xa82, 0xa52, 0xa22, 0x9f1, 0x9c0, 0x98f, 0x95e, 0x92c, 0x8fa, 0x8c8, 0x896, 0x864, 0x832, 0x800, 0x7cd, 0x79b, 0x769, 0x737, 0x705, 0x6d3, 0x6a1, 0x670, 0x63f, 0x60e, 0x5dd, 0x5ad, 0x57d, 0x54e, 0x51f, 0x4f0, 0x4c2, 0x494, 0x467, 0x43a, 0x40e, 0x3e3, 0x3b8, 0x38e, 0x365, 0x33c, 0x314, 0x2ed, 0x2c6, 0x2a0, 0x27c, 0x258, 0x235, 0x212, 0x1f1, 0x1d1, 0x1b1, 0x193, 0x175, 0x159, 0x13e, 0x123, 0x10a, 0xf2, 0xdb, 0xc5, 0xb0, 0x9c, 0x89, 0x78, 0x67, 0x58, 0x4a, 0x3d, 0x32, 0x27, 0x1e, 0x16, 0xf, 0xa, 0x6, 0x2, 0x1}; +#endif // AUDIO_DAC_SAMPLE_WAVEFORM_SINE +#ifdef AUDIO_DAC_SAMPLE_WAVEFORM_TRIANGLE +static const dacsample_t dac_buffer_triangle[AUDIO_DAC_BUFFER_SIZE] = { + // 256 values, max 4095 + 0x0, 0x20, 0x40, 0x60, 0x80, 0xa0, 0xc0, 0xe0, 0x100, 0x120, 0x140, 0x160, 0x180, 0x1a0, 0x1c0, 0x1e0, 0x200, 0x220, 0x240, 0x260, 0x280, 0x2a0, 0x2c0, 0x2e0, 0x300, 0x320, 0x340, 0x360, 0x380, 0x3a0, 0x3c0, 0x3e0, 0x400, 0x420, 0x440, 0x460, 0x480, 0x4a0, 0x4c0, 0x4e0, 0x500, 0x520, 0x540, 0x560, 0x580, 0x5a0, 0x5c0, 0x5e0, 0x600, 0x620, 0x640, 0x660, 0x680, 0x6a0, 0x6c0, 0x6e0, 0x700, 0x720, 0x740, 0x760, 0x780, 0x7a0, 0x7c0, 0x7e0, 0x800, 0x81f, 0x83f, 0x85f, 0x87f, 0x89f, 0x8bf, 0x8df, 0x8ff, 0x91f, 0x93f, 0x95f, 0x97f, 0x99f, 0x9bf, 0x9df, 0x9ff, 0xa1f, 0xa3f, 0xa5f, 0xa7f, 0xa9f, 0xabf, 0xadf, 0xaff, 0xb1f, 0xb3f, 0xb5f, 0xb7f, 0xb9f, 0xbbf, 0xbdf, 0xbff, 0xc1f, 0xc3f, 0xc5f, 0xc7f, 0xc9f, 0xcbf, 0xcdf, 0xcff, 0xd1f, 0xd3f, 0xd5f, 0xd7f, 0xd9f, 0xdbf, 0xddf, 0xdff, 0xe1f, 0xe3f, 0xe5f, 0xe7f, 0xe9f, 0xebf, 0xedf, 0xeff, 0xf1f, 0xf3f, 0xf5f, 0xf7f, 0xf9f, 0xfbf, 0xfdf, + 0xfff, 0xfdf, 0xfbf, 0xf9f, 0xf7f, 0xf5f, 0xf3f, 0xf1f, 0xeff, 0xedf, 0xebf, 0xe9f, 0xe7f, 0xe5f, 0xe3f, 0xe1f, 0xdff, 0xddf, 0xdbf, 0xd9f, 0xd7f, 0xd5f, 0xd3f, 0xd1f, 0xcff, 0xcdf, 0xcbf, 0xc9f, 0xc7f, 0xc5f, 0xc3f, 0xc1f, 0xbff, 0xbdf, 0xbbf, 0xb9f, 0xb7f, 0xb5f, 0xb3f, 0xb1f, 0xaff, 0xadf, 0xabf, 0xa9f, 0xa7f, 0xa5f, 0xa3f, 0xa1f, 0x9ff, 0x9df, 0x9bf, 0x99f, 0x97f, 0x95f, 0x93f, 0x91f, 0x8ff, 0x8df, 0x8bf, 0x89f, 0x87f, 0x85f, 0x83f, 0x81f, 0x800, 0x7e0, 0x7c0, 0x7a0, 0x780, 0x760, 0x740, 0x720, 0x700, 0x6e0, 0x6c0, 0x6a0, 0x680, 0x660, 0x640, 0x620, 0x600, 0x5e0, 0x5c0, 0x5a0, 0x580, 0x560, 0x540, 0x520, 0x500, 0x4e0, 0x4c0, 0x4a0, 0x480, 0x460, 0x440, 0x420, 0x400, 0x3e0, 0x3c0, 0x3a0, 0x380, 0x360, 0x340, 0x320, 0x300, 0x2e0, 0x2c0, 0x2a0, 0x280, 0x260, 0x240, 0x220, 0x200, 0x1e0, 0x1c0, 0x1a0, 0x180, 0x160, 0x140, 0x120, 0x100, 0xe0, 0xc0, 0xa0, 0x80, 0x60, 0x40, 0x20}; +#endif // AUDIO_DAC_SAMPLE_WAVEFORM_TRIANGLE +#ifdef AUDIO_DAC_SAMPLE_WAVEFORM_SQUARE +static const dacsample_t dac_buffer_square[AUDIO_DAC_BUFFER_SIZE] = { + [0 ... AUDIO_DAC_BUFFER_SIZE / 2 - 1] = 0, // first and + [AUDIO_DAC_BUFFER_SIZE / 2 ... AUDIO_DAC_BUFFER_SIZE - 1] = AUDIO_DAC_SAMPLE_MAX, // second half +}; +#endif // AUDIO_DAC_SAMPLE_WAVEFORM_SQUARE +/* +// four steps: 0, 1/3, 2/3 and 1 +static const dacsample_t dac_buffer_staircase[AUDIO_DAC_BUFFER_SIZE] = { + [0 ... AUDIO_DAC_BUFFER_SIZE/3 -1 ] = 0, + [AUDIO_DAC_BUFFER_SIZE / 4 ... AUDIO_DAC_BUFFER_SIZE / 2 -1 ] = AUDIO_DAC_SAMPLE_MAX / 3, + [AUDIO_DAC_BUFFER_SIZE / 2 ... 3 * AUDIO_DAC_BUFFER_SIZE / 4 -1 ] = 2 * AUDIO_DAC_SAMPLE_MAX / 3, + [3 * AUDIO_DAC_BUFFER_SIZE / 4 ... AUDIO_DAC_BUFFER_SIZE -1 ] = AUDIO_DAC_SAMPLE_MAX, +} +*/ +#ifdef AUDIO_DAC_SAMPLE_WAVEFORM_TRAPEZOID +static const dacsample_t dac_buffer_trapezoid[AUDIO_DAC_BUFFER_SIZE] = {0x0, 0x1f, 0x7f, 0xdf, 0x13f, 0x19f, 0x1ff, 0x25f, 0x2bf, 0x31f, 0x37f, 0x3df, 0x43f, 0x49f, 0x4ff, 0x55f, 0x5bf, 0x61f, 0x67f, 0x6df, 0x73f, 0x79f, 0x7ff, 0x85f, 0x8bf, 0x91f, 0x97f, 0x9df, 0xa3f, 0xa9f, 0xaff, 0xb5f, 0xbbf, 0xc1f, 0xc7f, 0xcdf, 0xd3f, 0xd9f, 0xdff, 0xe5f, 0xebf, 0xf1f, 0xf7f, 0xfdf, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, 0xfff, + 0xfff, 0xfdf, 0xf7f, 0xf1f, 0xebf, 0xe5f, 0xdff, 0xd9f, 0xd3f, 0xcdf, 0xc7f, 0xc1f, 0xbbf, 0xb5f, 0xaff, 0xa9f, 0xa3f, 0x9df, 0x97f, 0x91f, 0x8bf, 0x85f, 0x7ff, 0x79f, 0x73f, 0x6df, 0x67f, 0x61f, 0x5bf, 0x55f, 0x4ff, 0x49f, 0x43f, 0x3df, 0x37f, 0x31f, 0x2bf, 0x25f, 0x1ff, 0x19f, 0x13f, 0xdf, 0x7f, 0x1f, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}; +#endif // AUDIO_DAC_SAMPLE_WAVEFORM_TRAPEZOID + +static dacsample_t dac_buffer_empty[AUDIO_DAC_BUFFER_SIZE] = {AUDIO_DAC_OFF_VALUE}; + +/* keep track of the sample position for for each frequency */ +static float dac_if[AUDIO_MAX_SIMULTANEOUS_TONES] = {0.0}; + +static float active_tones_snapshot[AUDIO_MAX_SIMULTANEOUS_TONES] = {0, 0}; +static uint8_t active_tones_snapshot_length = 0; + +typedef enum { + OUTPUT_SHOULD_START, + OUTPUT_RUN_NORMALLY, + // path 1: wait for zero, then change/update active tones + OUTPUT_TONES_CHANGED, + OUTPUT_REACHED_ZERO_BEFORE_TONE_CHANGE, + // path 2: hardware should stop, wait for zero then turn output off = stop the timer + OUTPUT_SHOULD_STOP, + OUTPUT_REACHED_ZERO_BEFORE_OFF, + OUTPUT_OFF, + OUTPUT_OFF_1, + OUTPUT_OFF_2, // trailing off: giving the DAC two more conversion cycles until the AUDIO_DAC_OFF_VALUE reaches the output, then turn the timer off, which leaves the output at that level + number_of_output_states +} output_states_t; +output_states_t state = OUTPUT_OFF_2; + +/** + * Generation of the waveform being passed to the callback. Declared weak so users + * can override it with their own wave-forms/noises. + */ +__attribute__((weak)) uint16_t dac_value_generate(void) { + // DAC is running/asking for values but snapshot length is zero -> must be playing a pause + if (active_tones_snapshot_length == 0) { + return AUDIO_DAC_OFF_VALUE; + } + + /* doing additive wave synthesis over all currently playing tones = adding up + * sine-wave-samples for each frequency, scaled by the number of active tones + */ + uint16_t value = 0; + float frequency = 0.0f; + + for (uint8_t i = 0; i < active_tones_snapshot_length; i++) { + /* Note: a user implementation does not have to rely on the active_tones_snapshot, but + * could directly query the active frequencies through audio_get_processed_frequency */ + frequency = active_tones_snapshot[i]; + + dac_if[i] = dac_if[i] + ((frequency * AUDIO_DAC_BUFFER_SIZE) / AUDIO_DAC_SAMPLE_RATE) * 2 / 3; + /*Note: the 2/3 are necessary to get the correct frequencies on the + * DAC output (as measured with an oscilloscope), since the gpt + * timer runs with 3*AUDIO_DAC_SAMPLE_RATE; and the DAC callback + * is called twice per conversion.*/ + + dac_if[i] = fmod(dac_if[i], AUDIO_DAC_BUFFER_SIZE); + + // Wavetable generation/lookup + uint16_t dac_i = (uint16_t)dac_if[i]; + +#if defined(AUDIO_DAC_SAMPLE_WAVEFORM_SINE) + value += dac_buffer_sine[dac_i] / active_tones_snapshot_length; +#elif defined(AUDIO_DAC_SAMPLE_WAVEFORM_TRIANGLE) + value += dac_buffer_triangle[dac_i] / active_tones_snapshot_length; +#elif defined(AUDIO_DAC_SAMPLE_WAVEFORM_TRAPEZOID) + value += dac_buffer_trapezoid[dac_i] / active_tones_snapshot_length; +#elif defined(AUDIO_DAC_SAMPLE_WAVEFORM_SQUARE) + value += dac_buffer_square[dac_i] / active_tones_snapshot_length; +#endif + /* + // SINE + value += dac_buffer_sine[dac_i] / active_tones_snapshot_length / 3; + // TRIANGLE + value += dac_buffer_triangle[dac_i] / active_tones_snapshot_length / 3; + // SQUARE + value += dac_buffer_square[dac_i] / active_tones_snapshot_length / 3; + //NOTE: combination of these three wave-forms is more exemplary - and doesn't sound particularly good :-P + */ + + // STAIRS (mostly usefully as test-pattern) + // value_avg = dac_buffer_staircase[dac_i] / active_tones_snapshot_length; + } + + return value; +} + +/** + * DAC streaming callback. Does all of the main computing for playing songs. + * + * Note: chibios calls this CB twice: during the 'half buffer event', and the 'full buffer event'. + */ +static void dac_end(DACDriver *dacp) { + dacsample_t *sample_p = (dacp)->samples; + + // work on the other half of the buffer + if (dacIsBufferComplete(dacp)) { + sample_p += AUDIO_DAC_BUFFER_SIZE / 2; // 'half_index' + } + + for (uint8_t s = 0; s < AUDIO_DAC_BUFFER_SIZE / 2; s++) { + if (OUTPUT_OFF <= state) { + sample_p[s] = AUDIO_DAC_OFF_VALUE; + continue; + } else { + sample_p[s] = dac_value_generate(); + } + + /* zero crossing (or approach, whereas zero == DAC_OFF_VALUE, which can be configured to anything from 0 to DAC_SAMPLE_MAX) + * ============================*=*========================== AUDIO_DAC_SAMPLE_MAX + * * * + * * * + * --------------------------------------------------------- + * * * } AUDIO_DAC_SAMPLE_MAX/100 + * --------------------------------------------------------- AUDIO_DAC_OFF_VALUE + * * * } AUDIO_DAC_SAMPLE_MAX/100 + * --------------------------------------------------------- + * * + * * * + * * * + * =====*=*================================================= 0x0 + */ + if (((sample_p[s] + (AUDIO_DAC_SAMPLE_MAX / 100)) > AUDIO_DAC_OFF_VALUE) && // value approaches from below + (sample_p[s] < (AUDIO_DAC_OFF_VALUE + (AUDIO_DAC_SAMPLE_MAX / 100))) // or above + ) { + if ((OUTPUT_SHOULD_START == state) && (active_tones_snapshot_length > 0)) { + state = OUTPUT_RUN_NORMALLY; + } else if (OUTPUT_TONES_CHANGED == state) { + state = OUTPUT_REACHED_ZERO_BEFORE_TONE_CHANGE; + } else if (OUTPUT_SHOULD_STOP == state) { + state = OUTPUT_REACHED_ZERO_BEFORE_OFF; + } + } + + // still 'ramping up', reset the output to OFF_VALUE until the generated values reach that value, to do a smooth handover + if (OUTPUT_SHOULD_START == state) { + sample_p[s] = AUDIO_DAC_OFF_VALUE; + } + + if ((OUTPUT_SHOULD_START == state) || (OUTPUT_REACHED_ZERO_BEFORE_OFF == state) || (OUTPUT_REACHED_ZERO_BEFORE_TONE_CHANGE == state)) { + uint8_t active_tones = MIN(AUDIO_MAX_SIMULTANEOUS_TONES, audio_get_number_of_active_tones()); + active_tones_snapshot_length = 0; + // update the snapshot - once, and only on occasion that something changed; + // -> saves cpu cycles (?) + for (uint8_t i = 0; i < active_tones; i++) { + float freq = audio_get_processed_frequency(i); + if (freq > 0) { // disregard 'rest' notes, with valid frequency 0.0f; which would only lower the resulting waveform volume during the additive synthesis step + active_tones_snapshot[active_tones_snapshot_length++] = freq; + } + } + + if ((0 == active_tones_snapshot_length) && (OUTPUT_REACHED_ZERO_BEFORE_OFF == state)) { + state = OUTPUT_OFF; + } + if (OUTPUT_REACHED_ZERO_BEFORE_TONE_CHANGE == state) { + state = OUTPUT_RUN_NORMALLY; + } + } + } + + // update audio internal state (note position, current_note, ...) + if (audio_update_state()) { + if (OUTPUT_SHOULD_STOP != state) { + state = OUTPUT_TONES_CHANGED; + } + } + + if (OUTPUT_OFF <= state) { + if (OUTPUT_OFF_2 == state) { + // stopping timer6 = stopping the DAC at whatever value it is currently pushing to the output = AUDIO_DAC_OFF_VALUE + gptStopTimer(&GPTD6); + } else { + state++; + } + } +} + +static void dac_error(DACDriver *dacp, dacerror_t err) { + (void)dacp; + (void)err; + + chSysHalt("DAC failure. halp"); +} + +static const GPTConfig gpt6cfg1 = {.frequency = AUDIO_DAC_SAMPLE_RATE * 3, + .callback = NULL, + .cr2 = TIM_CR2_MMS_1, /* MMS = 010 = TRGO on Update Event. */ + .dier = 0U}; + +static const DACConfig dac_conf = {.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_cfg = {.num_channels = 1U, .end_cb = dac_end, .error_cb = dac_error, .trigger = DAC_TRG(0b000)}; + +void audio_driver_initialize() { + if ((AUDIO_PIN == A4) || (AUDIO_PIN_ALT == A4)) { + palSetLineMode(A4, PAL_MODE_INPUT_ANALOG); + dacStart(&DACD1, &dac_conf); + } + if ((AUDIO_PIN == A5) || (AUDIO_PIN_ALT == A5)) { + palSetLineMode(A5, PAL_MODE_INPUT_ANALOG); + dacStart(&DACD2, &dac_conf); + } + + /* 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; + + if (AUDIO_PIN == A4) { + dacStartConversion(&DACD1, &dac_conv_cfg, dac_buffer_empty, AUDIO_DAC_BUFFER_SIZE); + } else if (AUDIO_PIN == A5) { + dacStartConversion(&DACD2, &dac_conv_cfg, dac_buffer_empty, AUDIO_DAC_BUFFER_SIZE); + } + + // no inverted/out-of-phase waveform (yet?), only pulling AUDIO_PIN_ALT to AUDIO_DAC_OFF_VALUE +#if defined(AUDIO_PIN_ALT_AS_NEGATIVE) + if (AUDIO_PIN_ALT == A4) { + dacPutChannelX(&DACD1, 0, AUDIO_DAC_OFF_VALUE); + } else if (AUDIO_PIN_ALT == A5) { + dacPutChannelX(&DACD2, 0, AUDIO_DAC_OFF_VALUE); + } +#endif + + gptStart(&GPTD6, &gpt6cfg1); +} + +void audio_driver_stop(void) { state = OUTPUT_SHOULD_STOP; } + +void audio_driver_start(void) { + gptStartContinuous(&GPTD6, 2U); + + for (uint8_t i = 0; i < AUDIO_MAX_SIMULTANEOUS_TONES; i++) { + dac_if[i] = 0.0f; + active_tones_snapshot[i] = 0.0f; + } + active_tones_snapshot_length = 0; + state = OUTPUT_SHOULD_START; +} |