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Reduce popping during audio initialization using the additive DAC #21642

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merged 3 commits into from
Sep 25, 2023
Merged

Reduce popping during audio initialization using the additive DAC #21642

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48b36fd
Reduce popping during audio initialization using the additive DAC
Nebuleon Jul 30, 2023
b32e303
Lint the previous commit
Nebuleon Jul 30, 2023
9b061a5
dac_additive: Rework initialization; clarify use of "dac_buffer_empty"
Nebuleon Aug 3, 2023
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13 changes: 10 additions & 3 deletions platforms/chibios/drivers/audio_dac_additive.c
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Original file line number Diff line number Diff line change
Expand Up @@ -84,7 +84,7 @@ static const dacsample_t dac_buffer_trapezoid[AUDIO_DAC_BUFFER_SIZE] = {0x0, 0
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};
static dacsample_t dac_buffer[AUDIO_DAC_BUFFER_SIZE];

/* keep track of the sample position for for each frequency */
static float dac_if[AUDIO_MAX_SIMULTANEOUS_TONES] = {0.0};
Expand Down Expand Up @@ -308,10 +308,17 @@ void audio_driver_initialize(void) {
DACD1.params->dac->CR &= ~DAC_CR_BOFF1;
DACD2.params->dac->CR &= ~DAC_CR_BOFF2;

/* Start the DAC output with all off values. This buffer will then get fed
* with samples from dac_end, which will play notes.
*/
for (size_t i = 0; i < AUDIO_DAC_BUFFER_SIZE; i++) {
dac_buffer[i] = AUDIO_DAC_OFF_VALUE;
}

if (AUDIO_PIN == A4) {
dacStartConversion(&DACD1, &dac_conv_cfg, dac_buffer_empty, AUDIO_DAC_BUFFER_SIZE);
dacStartConversion(&DACD1, &dac_conv_cfg, dac_buffer, AUDIO_DAC_BUFFER_SIZE);
} else if (AUDIO_PIN == A5) {
dacStartConversion(&DACD2, &dac_conv_cfg, dac_buffer_empty, AUDIO_DAC_BUFFER_SIZE);
dacStartConversion(&DACD2, &dac_conv_cfg, dac_buffer, AUDIO_DAC_BUFFER_SIZE);
}

// no inverted/out-of-phase waveform (yet?), only pulling AUDIO_PIN_ALT to AUDIO_DAC_OFF_VALUE
Expand Down