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nrf: PDMIn: Implement

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So far, this supports only 16kHz and 16-bit samples with a fixed gain.
This is enough to support the basic functionality of e.g., sensing
ambient audio levels.
This commit is contained in:
Jeff Epler 2019-08-15 19:31:42 -05:00 committed by jepler
parent 79f8a85786
commit 912fd7759d
2 changed files with 77 additions and 14 deletions
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84
ports/nrf/common-hal/audiobusio/PDMIn.c
View File

@ -25,9 +25,15 @@
*/
#include "common-hal/audiobusio/PDMIn.h"
#include "shared-bindings/microcontroller/Pin.h"
#include "py/runtime.h"
__attribute__((used))
NRF_PDM_Type *nrf_pdm = NRF_PDM;
static uint32_t dummy_buffer[4];
void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t* self,
const mcu_pin_obj_t* clock_pin,
const mcu_pin_obj_t* data_pin,
@ -35,30 +41,90 @@ void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t* self,
uint8_t bit_depth,
bool mono,
uint8_t oversample) {
mp_raise_RuntimeError(translate("not implemented"));
assert_pin_free(clock_pin);
assert_pin_free(data_pin);
claim_pin(clock_pin);
claim_pin(data_pin);
self->mono = mono;
self->clock_pin_number = clock_pin->number;
self->data_pin_number = data_pin->number;
if (sample_rate != 16000) {
mp_raise_ValueError(translate("only sample_rate=16000 is supported"));
}
if (bit_depth != 16) {
mp_raise_ValueError(translate("only bit_depth=16 is supported"));
}
nrf_pdm->PSEL.CLK = self->clock_pin_number;
nrf_pdm->PSEL.DIN = self->data_pin_number;
nrf_pdm->PDMCLKCTRL = PDM_PDMCLKCTRL_FREQ_Default; // For Ratio64
nrf_pdm->RATIO = PDM_RATIO_RATIO_Ratio64;
nrf_pdm->GAINL = PDM_GAINL_GAINL_DefaultGain;
nrf_pdm->GAINR = PDM_GAINR_GAINR_DefaultGain;
nrf_pdm->ENABLE = 1;
nrf_pdm->SAMPLE.PTR = (uintptr_t)&dummy_buffer;
nrf_pdm->SAMPLE.MAXCNT = 1;
nrf_pdm->TASKS_START = 1;
}
bool common_hal_audiobusio_pdmin_deinited(audiobusio_pdmin_obj_t* self) {
mp_raise_RuntimeError(translate("not implemented"));
return !self->clock_pin_number;
}
void common_hal_audiobusio_pdmin_deinit(audiobusio_pdmin_obj_t* self) {
mp_raise_RuntimeError(translate("not implemented"));
nrf_pdm->ENABLE = 0;
reset_pin_number(self->clock_pin_number);
self->clock_pin_number = 0;
reset_pin_number(self->data_pin_number);
self->data_pin_number = 0;
}
uint8_t common_hal_audiobusio_pdmin_get_bit_depth(audiobusio_pdmin_obj_t* self) {
return self->bit_depth;
return 16;
}
uint32_t common_hal_audiobusio_pdmin_get_sample_rate(audiobusio_pdmin_obj_t* self) {
return self->sample_rate;
return 16000;
}
uint32_t common_hal_audiobusio_pdmin_record_to_buffer(audiobusio_pdmin_obj_t* self,
uint16_t* output_buffer, uint32_t output_buffer_length) {
mp_raise_RuntimeError(translate("not implemented"));
}
// Note: Adafruit's module has SELECT pulled to GND, which makes the DATA
// valid when the CLK is low, therefore it must be sampled on the rising edge.
if (self->mono) {
nrf_pdm->MODE = PDM_MODE_OPERATION_Stereo | PDM_MODE_EDGE_LeftRising;
} else {
nrf_pdm->MODE = PDM_MODE_OPERATION_Mono | PDM_MODE_EDGE_LeftRising;
}
void common_hal_audiobusio_pdmin_record_to_file(audiobusio_pdmin_obj_t* self, uint8_t* buffer, uint32_t length) {
mp_raise_RuntimeError(translate("not implemented"));
// step 1. Redirect to real buffer
nrf_pdm->SAMPLE.PTR = (uintptr_t)output_buffer;
nrf_pdm->SAMPLE.MAXCNT = output_buffer_length;
// a delay is the safest simple way to ensure that the above requested sample has started
mp_hal_delay_us(200);
nrf_pdm->EVENTS_END = 0;
// step 2. Registers are double buffered, so pre-redirect back to dummy buffer
nrf_pdm->SAMPLE.PTR = (uintptr_t)&dummy_buffer;
nrf_pdm->SAMPLE.MAXCNT = 1;
// Step 3. wait for PDM to end
while (!nrf_pdm->EVENTS_END) {
MICROPY_VM_HOOK_LOOP;
}
// Step 4. They want unsigned
for (uint32_t i=0; i<output_buffer_length; i++) {
output_buffer[i] += 32768;
}
if (self->mono) {
return (output_buffer_length / 2) * 2;
} else {
return (output_buffer_length / 4) * 4;
}
}

7
ports/nrf/common-hal/audiobusio/PDMIn.h
View File

@ -33,11 +33,8 @@
typedef struct {
mp_obj_base_t base;
const mcu_pin_obj_t *clock_pin;
const mcu_pin_obj_t *data_pin;
uint32_t sample_rate;
uint8_t bytes_per_sample;
uint8_t bit_depth;
uint8_t clock_pin_number, data_pin_number;
bool mono;
} audiobusio_pdmin_obj_t;
#endif