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Merge pull request #927 from dhalbert/pdmin_serializer_on_off 

PDMIn: turn serializer on when starting DMA
This commit is contained in:
Scott Shawcroft 2018-06-12 10:42:08 -07:00 committed by GitHub
parent d427ed64a2 4691b30c02
commit ab0bc1c2f8
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 9 additions and 7 deletions
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16
ports/atmel-samd/common-hal/audiobusio/PDMIn.c
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@ -203,9 +203,9 @@ void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t* self,
i2s_set_enable(true);
// Run the serializer all the time. This eliminates startup delay for the microphone.
// Run the clock all the time. This eliminates startup delay for the microphone,
// which can be 10-100ms. Turn serializer on as needed.
i2s_set_clock_unit_enable(self->clock_unit, true);
i2s_set_serializer_enable(self->serializer, true);
claim_pin(clock_pin);
claim_pin(data_pin);
@ -379,6 +379,8 @@ uint32_t common_hal_audiobusio_pdmin_record_to_buffer(audiobusio_pdmin_obj_t* se
dma_configure(dma_channel, trigger_source, true);
init_event_channel_interrupt(event_channel, CORE_GCLK, EVSYS_ID_GEN_DMAC_CH_0 + dma_channel);
// Turn on serializer now to get it in sync with DMA.
i2s_set_serializer_enable(self->serializer, true);
dma_enable_channel(dma_channel);
// Record
@ -399,11 +401,9 @@ uint32_t common_hal_audiobusio_pdmin_record_to_buffer(audiobusio_pdmin_obj_t* se
#ifdef SAMD51
#define MAX_WAIT_COUNTS 6000
#endif
while (!event_interrupt_active(event_channel)) {
if (wait_counts++ > MAX_WAIT_COUNTS) {
// Buffer has stopped filling; DMA may have missed an I2S trigger event.
break;
}
// If wait_counts exceeds the max count, buffer has probably stopped filling;
// DMA may have missed an I2S trigger event.
while (!event_interrupt_active(event_channel) && ++wait_counts < MAX_WAIT_COUNTS) {
#ifdef MICROPY_VM_HOOK_LOOP
MICROPY_VM_HOOK_LOOP
#endif
@ -463,6 +463,8 @@ uint32_t common_hal_audiobusio_pdmin_record_to_buffer(audiobusio_pdmin_obj_t* se
disable_event_channel(event_channel);
dma_disable_channel(dma_channel);
// Turn off serializer, but leave clock on, to avoid mic startup delay.
i2s_set_serializer_enable(self->serializer, false);
return values_output;
}