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nrf: Add i2s audio output

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Testing performed: I used a Particle Xenon with a HDA1334 I2S DAC.
I played a variety of mono 16-bit samples at 11025 and 22050Hz nominal
bit rates.  With this setup, all the 11025Hz samples sound good.
I tested play, pause,  and loop functionality.

During some runs with 22050Hz samples, there were glitches.  However,
these may have only occurred during runs where I had set breakpoints
and watchpoints in gdb.

I also tested with a MAX98357A I2S amplifier.  On this device, everything
sounded "scratchy".  I was powering it from 5V and the 5V rail seemed
steady, so I don't have an explanation for this.  However, I haven't
tried it with a SAMD board.
This commit is contained in:
jepler 2019-09-08 13:08:15 -05:00
parent bd7b03fc7e
commit f38ee42874
4 changed files with 297 additions and 9 deletions
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8
ports/nrf/background.c
View File

@ -33,6 +33,10 @@
#include "shared-module/displayio/__init__.h"
#endif
#if CIRCUITPY_AUDIOBUSIO
#include "common-hal/audiobusio/I2SOut.h"
#endif
#if CIRCUITPY_AUDIOPWMIO
#include "common-hal/audiopwmio/PWMAudioOut.h"
#endif
@ -54,6 +58,10 @@ void run_background_tasks(void) {
#if CIRCUITPY_AUDIOPWMIO
audiopwmout_background();
#endif
#if CIRCUITPY_AUDIOBUSIO
i2s_background();
#endif
#if CIRCUITPY_DISPLAYIO
displayio_background();

262
ports/nrf/common-hal/audiobusio/I2SOut.c
View File

@ -24,47 +24,291 @@
* THE SOFTWARE.
*/
#include <math.h>
#include <string.h>
#include "common-hal/microcontroller/Pin.h"
#include "common-hal/audiobusio/I2SOut.h"
#include "shared-bindings/audiobusio/I2SOut.h"
#include "shared-module/audiocore/__init__.h"
#include "py/obj.h"
#include "py/runtime.h"
static audiobusio_i2sout_obj_t *instance;
struct { int16_t l, r; } static_sample16 = {0x8000, 0x8000};
struct { uint8_t l1, r1, l2, r2; } static_sample8 = {0x80, 0x80, 0x80, 0x80};
struct frequency_info { uint32_t RATIO; uint32_t MCKFREQ; int sample_rate; float abserr; };
struct ratio_info { uint32_t RATIO; int16_t divisor; bool can_16bit; };
struct ratio_info ratios[] = {
{ I2S_CONFIG_RATIO_RATIO_32X, 32, true },
{ I2S_CONFIG_RATIO_RATIO_48X, 48, false },
{ I2S_CONFIG_RATIO_RATIO_64X, 64, true },
{ I2S_CONFIG_RATIO_RATIO_96X, 96, true },
{ I2S_CONFIG_RATIO_RATIO_128X, 128, true },
{ I2S_CONFIG_RATIO_RATIO_192X, 192, true },
{ I2S_CONFIG_RATIO_RATIO_256X, 256, true },
{ I2S_CONFIG_RATIO_RATIO_384X, 384, true },
{ I2S_CONFIG_RATIO_RATIO_512X, 512, true },
};
struct mclk_info { uint32_t MCKFREQ; int divisor; };
struct mclk_info mclks[] = {
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV8, 8 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV10, 10 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV11, 11 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV15, 15 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV16, 16 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV21, 21 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV23, 23 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV31, 31 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV42, 42 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV63, 63 },
{ I2S_CONFIG_MCKFREQ_MCKFREQ_32MDIV125, 125 },
};
static void calculate_ratio_info(uint32_t target_sample_rate, struct frequency_info *info,
int ratio_index, int mclk_index) {
info->RATIO = ratios[ratio_index].RATIO;
info->MCKFREQ = mclks[mclk_index].MCKFREQ;
info->sample_rate = 32000000
/ ratios[ratio_index].divisor / mclks[mclk_index].divisor;
info->abserr = fabsf(1.0f * target_sample_rate - info->sample_rate)
/ target_sample_rate;
}
void choose_i2s_clocking(audiobusio_i2sout_obj_t *self, uint32_t sample_rate) {
struct frequency_info best = {0, 0, 0, 1.0};
for (size_t ri=0; ri<sizeof(ratios) / sizeof(ratios[0]); ri++) {
if (NRF_I2S->CONFIG.SWIDTH == I2S_CONFIG_SWIDTH_SWIDTH_16Bit
&& !ratios[ri].can_16bit) {
continue;
}
for (size_t mi=0; mi<sizeof(mclks) / sizeof(mclks[0]); mi++) {
struct frequency_info info = {0, 0, 1.0};
calculate_ratio_info(sample_rate, &info, ri, mi);
if (info.abserr < best.abserr) {
best = info;
}
#ifdef DEBUG_CLOCKING
mp_printf(&mp_plat_print,
"RATIO=%3d MCKFREQ=%08x rate=%d abserr=%.4f\n",
info.RATIO, info.MCKFREQ, info.sample_rate,
(double)info.abserr);
#endif
}
}
NRF_I2S->CONFIG.RATIO = best.RATIO;
NRF_I2S->CONFIG.MCKFREQ = best.MCKFREQ;
self->sample_rate = best.sample_rate;
}
static void i2s_buffer_fill(audiobusio_i2sout_obj_t* self) {
void *buffer = self->buffers[self->next_buffer];
NRF_I2S->TXD.PTR = (uintptr_t)buffer;
self->next_buffer = !self->next_buffer;
size_t bytesleft = self->buffer_length;
if (self->paused || self->stopping) {
if (self->stopping) {
NRF_I2S->TASKS_STOP = 1;
self->playing = false;
}
stopping: ;
uint32_t *bp = (uint32_t*)buffer;
uint32_t *be = (uint32_t*)(buffer + bytesleft);
for (; bp != be; )
*bp++ = self->hold_value;
return;
}
while (bytesleft) {
if (self->sample_data == self->sample_end) {
uint32_t sample_buffer_length;
audioio_get_buffer_result_t get_buffer_result =
audiosample_get_buffer(self->sample, false, 0,
&self->sample_data, &sample_buffer_length);
self->sample_end = self->sample_data + sample_buffer_length;
if (get_buffer_result == GET_BUFFER_DONE) {
if (self->loop) {
audiosample_reset_buffer(self->sample, false, 0);
} else {
self->stopping = true;
goto stopping;
}
}
}
uint16_t bytecount = MIN(bytesleft, (size_t)(self->sample_end - self->sample_data));
if (self->samples_signed) {
memcpy(buffer, self->sample_data, bytecount);
} else if (self->bytes_per_sample == 2) {
uint16_t *bp = (uint16_t*)buffer;
uint16_t *be = (uint16_t*)(buffer + bytecount);
uint16_t *sp = (uint16_t*)self->sample_data;
for (; bp != be; bp++) {
*bp++ = *sp++ + 0x8000;
}
} else {
uint8_t *bp = (uint8_t*)buffer;
uint8_t *be = (uint8_t*)(buffer + bytecount);
uint8_t *sp = (uint8_t*)self->sample_data;
for (; bp != be; bp++) {
*bp++ = *sp++ + 0x80;
}
}
buffer += bytecount;
self->sample_data += bytecount;
bytesleft -= bytecount;
}
if (self->bytes_per_sample == 1 && self->channel_count == 1) {
self->hold_value = 0x01010101 * *(uint8_t*)(buffer-1);
} else if (self->bytes_per_sample == 2 && self->channel_count == 2) {
self->hold_value = *(uint32_t*)(buffer-4);
} else {
self->hold_value = 0x00010001 * *(uint16_t*)(buffer-2);
}
}
void common_hal_audiobusio_i2sout_construct(audiobusio_i2sout_obj_t* self,
const mcu_pin_obj_t* bit_clock, const mcu_pin_obj_t* word_select,
const mcu_pin_obj_t* data, bool left_justified) {
mp_raise_NotImplementedError(NULL);
if (instance)
mp_raise_RuntimeError(translate("Device in use"));
instance = self;
claim_pin(bit_clock);
claim_pin(word_select);
claim_pin(data);
NRF_I2S->PSEL.SCK = self->bit_clock_pin_number = bit_clock->number;
NRF_I2S->PSEL.LRCK = self->word_select_pin_number = word_select->number;
NRF_I2S->PSEL.SDOUT = self->data_pin_number = data->number;
NRF_I2S->CONFIG.MODE = I2S_CONFIG_MODE_MODE_Master;
NRF_I2S->CONFIG.RXEN = I2S_CONFIG_RXEN_RXEN_Disabled;
NRF_I2S->CONFIG.TXEN = I2S_CONFIG_TXEN_TXEN_Enabled;
NRF_I2S->CONFIG.MCKEN = I2S_CONFIG_MCKEN_MCKEN_Enabled;
NRF_I2S->CONFIG.SWIDTH = I2S_CONFIG_SWIDTH_SWIDTH_16Bit;
NRF_I2S->CONFIG.ALIGN = I2S_CONFIG_ALIGN_ALIGN_Left;
NRF_I2S->CONFIG.FORMAT = left_justified ? I2S_CONFIG_FORMAT_FORMAT_Aligned
: I2S_CONFIG_FORMAT_FORMAT_I2S;
}
bool common_hal_audiobusio_i2sout_deinited(audiobusio_i2sout_obj_t* self) {
mp_raise_NotImplementedError(NULL);
return self->data_pin_number == 0xff;
}
void common_hal_audiobusio_i2sout_deinit(audiobusio_i2sout_obj_t* self) {
mp_raise_NotImplementedError(NULL);
if (common_hal_audiobusio_i2sout_deinited(self)) {
return;
}
reset_pin_number(self->bit_clock_pin_number);
self->bit_clock_pin_number = 0xff;
reset_pin_number(self->word_select_pin_number);
self->word_select_pin_number = 0xff;
reset_pin_number(self->data_pin_number);
self->data_pin_number = 0xff;
instance = NULL;
}
void common_hal_audiobusio_i2sout_play(audiobusio_i2sout_obj_t* self,
mp_obj_t sample, bool loop) {
mp_raise_NotImplementedError(NULL);
if (common_hal_audiobusio_i2sout_get_playing(self)) {
common_hal_audiobusio_i2sout_stop(self);
}
self->sample = sample;
self->loop = loop;
uint32_t sample_rate = audiosample_sample_rate(sample);
self->bytes_per_sample = audiosample_bits_per_sample(sample) / 8;
uint32_t max_buffer_length;
bool single_buffer, samples_signed;
audiosample_get_buffer_structure(sample, /* single channel */ false,
&single_buffer, &samples_signed, &max_buffer_length,
&self->channel_count);
self->single_buffer = single_buffer;
self->samples_signed = samples_signed;
choose_i2s_clocking(self, sample_rate);
/* Allocate buffers based on a maximum duration */
enum { buffer_length_ms = 8 };
self->buffer_length = MAX(
2*max_buffer_length,
sample_rate * buffer_length_ms * self->bytes_per_sample
* self->channel_count / 1000);
self->buffer_length = (self->buffer_length + 3) & ~3;
self->buffers[0] = m_malloc(self->buffer_length, false);
self->buffers[1] = m_malloc(self->buffer_length, false);
audiosample_reset_buffer(self->sample, false, 0);
self->next_buffer = 0;
self->sample_data = self->sample_end = 0;
self->playing = true;
self->paused = false;
self->stopping = false;
i2s_buffer_fill(self);
NRF_I2S->CONFIG.CHANNELS = self->channel_count == 1 ? I2S_CONFIG_CHANNELS_CHANNELS_Left : I2S_CONFIG_CHANNELS_CHANNELS_Stereo;
NRF_I2S->RXTXD.MAXCNT = self->buffer_length / 4;
NRF_I2S->ENABLE = I2S_ENABLE_ENABLE_Enabled;
NRF_I2S->TASKS_START = 1;
i2s_background();
}
void common_hal_audiobusio_i2sout_pause(audiobusio_i2sout_obj_t* self) {
mp_raise_NotImplementedError(NULL);
self->paused = true;
}
void common_hal_audiobusio_i2sout_resume(audiobusio_i2sout_obj_t* self) {
mp_raise_NotImplementedError(NULL);
self->paused = false;
}
bool common_hal_audiobusio_i2sout_get_paused(audiobusio_i2sout_obj_t* self) {
mp_raise_NotImplementedError(NULL);
return self->paused;
}
void common_hal_audiobusio_i2sout_stop(audiobusio_i2sout_obj_t* self) {
mp_raise_NotImplementedError(NULL);
NRF_I2S->TASKS_STOP = 1;
self->stopping = true;
}
bool common_hal_audiobusio_i2sout_get_playing(audiobusio_i2sout_obj_t* self) {
mp_raise_NotImplementedError(NULL);
if (NRF_I2S->EVENTS_STOPPED) {
self->playing = false;
NRF_I2S->EVENTS_STOPPED = 0;
}
return self->playing;
}
void i2s_background(void) {
if (NRF_I2S->EVENTS_TXPTRUPD) {
NRF_I2S->EVENTS_TXPTRUPD = 0;
if (instance) {
i2s_buffer_fill(instance);
} else {
NRF_I2S->TASKS_STOP = 1;
}
}
}
void i2s_reset(void) {
NRF_I2S->TASKS_STOP = 1;
NRF_I2S->ENABLE = I2S_ENABLE_ENABLE_Disabled;
NRF_I2S->PSEL.MCK = 0xFFFFFFFF;
NRF_I2S->PSEL.SCK = 0xFFFFFFFF;
NRF_I2S->PSEL.LRCK = 0xFFFFFFFF;
NRF_I2S->PSEL.SDOUT = 0xFFFFFFFF;
NRF_I2S->PSEL.SDIN = 0xFFFFFFFF;
instance = NULL;
}

27
ports/nrf/common-hal/audiobusio/I2SOut.h
View File

@ -31,6 +31,33 @@
typedef struct {
mp_obj_base_t base;
mp_obj_t *sample;
uint8_t *buffers[2];
uint8_t *sample_data, *sample_end;
uint16_t buffer_length;
uint16_t sample_rate;
uint32_t hold_value;
uint8_t next_buffer;
uint8_t bit_clock_pin_number;
uint8_t word_select_pin_number;
uint8_t data_pin_number;
uint8_t channel_count;
uint8_t bytes_per_sample;
bool left_justified : 1;
bool playing : 1;
bool stopping : 1;
bool paused : 1;
bool loop : 1;
bool samples_signed : 1;
bool single_buffer : 1;
} audiobusio_i2sout_obj_t;
void i2s_reset(void);
void i2s_background(void);
#endif // MICROPY_INCLUDED_NRF_COMMON_HAL_AUDIOBUSIO_I2SOUT_H

9
ports/nrf/supervisor/port.c
View File

@ -50,6 +50,10 @@
#include "shared-bindings/rtc/__init__.h"
#ifdef CIRCUITPY_AUDIOBUSIO
#include "common-hal/audiobusio/I2SOut.h"
#endif
#ifdef CIRCUITPY_AUDIOPWMIO
#include "common-hal/audiopwmio/PWMAudioOut.h"
#endif
@ -98,10 +102,15 @@ void reset_port(void) {
spi_reset();
uart_reset();
#ifdef CIRCUITPY_AUDIOBUSIO
i2s_reset();
#endif
#ifdef CIRCUITPY_AUDIOPWMIO
audiopwmout_reset();
#endif
#if CIRCUITPY_PULSEIO
pwmout_reset();
pulseout_reset();