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micropython/ports/esp32/machine_i2s.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2021 Mike Teachman
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
// This file is never compiled standalone, it's included directly from
// extmod/machine_i2s.c via MICROPY_PY_MACHINE_I2S_INCLUDEFILE.
#include "py/mphal.h"
#include "driver/i2s.h"
#include "soc/i2s_reg.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/queue.h"
#include "esp_task.h"
// Notes on this port's specific implementation of I2S:
// - a FreeRTOS task is created to implement the asynchronous background operations
// - a FreeRTOS queue is used to transfer the supplied buffer to the background task
// - all sample data transfers use DMA
#define I2S_TASK_PRIORITY (ESP_TASK_PRIO_MIN + 1)
#define I2S_TASK_STACK_SIZE (2048)
#define DMA_BUF_LEN_IN_I2S_FRAMES (256)
// The transform buffer is used with the readinto() method to bridge the opaque DMA memory on the ESP devices
// with the app buffer. It facilitates audio sample transformations. e.g. 32-bits samples to 16-bit samples.
// The size of 240 bytes is an engineering optimum that balances transfer performance with an acceptable use of heap space
#define SIZEOF_TRANSFORM_BUFFER_IN_BYTES (240)
typedef enum {
I2S_TX_TRANSFER,
I2S_RX_TRANSFER,
} direction_t;
typedef struct _non_blocking_descriptor_t {
mp_buffer_info_t appbuf;
mp_obj_t callback;
direction_t direction;
} non_blocking_descriptor_t;
typedef struct _machine_i2s_obj_t {
mp_obj_base_t base;
i2s_port_t i2s_id;
mp_hal_pin_obj_t sck;
mp_hal_pin_obj_t ws;
mp_hal_pin_obj_t sd;
int8_t mode;
i2s_bits_per_sample_t bits;
format_t format;
int32_t rate;
int32_t ibuf;
mp_obj_t callback_for_non_blocking;
io_mode_t io_mode;
uint8_t transform_buffer[SIZEOF_TRANSFORM_BUFFER_IN_BYTES];
QueueHandle_t i2s_event_queue;
QueueHandle_t non_blocking_mode_queue;
TaskHandle_t non_blocking_mode_task;
} machine_i2s_obj_t;
STATIC mp_obj_t machine_i2s_deinit(mp_obj_t self_in);
// The frame map is used with the readinto() method to transform the audio sample data coming
// from DMA memory (32-bit stereo, with the L and R channels reversed) to the format specified
// in the I2S constructor. e.g. 16-bit mono
STATIC const int8_t i2s_frame_map[NUM_I2S_USER_FORMATS][I2S_RX_FRAME_SIZE_IN_BYTES] = {
{ 6, 7, -1, -1, -1, -1, -1, -1 }, // Mono, 16-bits
{ 4, 5, 6, 7, -1, -1, -1, -1 }, // Mono, 32-bits
{ 6, 7, 2, 3, -1, -1, -1, -1 }, // Stereo, 16-bits
{ 4, 5, 6, 7, 0, 1, 2, 3 }, // Stereo, 32-bits
};
void machine_i2s_init0() {
for (i2s_port_t p = 0; p < I2S_NUM_AUTO; p++) {
MP_STATE_PORT(machine_i2s_obj)[p] = NULL;
}
}
// The following function takes a sample buffer and swaps L/R channels
//
// Background: For 32-bit stereo, the ESP-IDF API has a L/R channel orientation that breaks
// convention with other ESP32 channel formats
//
// appbuf[] = [L_0-7, L_8-15, L_16-23, L_24-31, R_0-7, R_8-15, R_16-23, R_24-31] = [Left channel, Right channel]
// dma[] = [R_0-7, R_8-15, R_16-23, R_24-31, L_0-7, L_8-15, L_16-23, L_24-31] = [Right channel, Left channel]
//
// where:
// L_0-7 is the least significant byte of the 32 bit sample in the Left channel
// L_24-31 is the most significant byte of the 32 bit sample in the Left channel
//
// Example:
//
// appbuf[] = [0x99, 0xBB, 0x11, 0x22, 0x44, 0x55, 0xAB, 0x77] = [Left channel, Right channel]
// dma[] = [0x44, 0x55, 0xAB, 0x77, 0x99, 0xBB, 0x11, 0x22] = [Right channel, Left channel]
// where:
// LEFT Channel = 0x99, 0xBB, 0x11, 0x22
// RIGHT Channel = 0x44, 0x55, 0xAB, 0x77
//
// samples in appbuf are in little endian format:
// 0x77 is the most significant byte of the 32-bit sample
// 0x44 is the least significant byte of the 32-bit sample
STATIC void swap_32_bit_stereo_channels(mp_buffer_info_t *bufinfo) {
int32_t swap_sample;
int32_t *sample = bufinfo->buf;
uint32_t num_samples = bufinfo->len / 4;
for (uint32_t i = 0; i < num_samples; i += 2) {
swap_sample = sample[i + 1];
sample[i + 1] = sample[i];
sample[i] = swap_sample;
}
}
STATIC int8_t get_frame_mapping_index(i2s_bits_per_sample_t bits, format_t format) {
if (format == MONO) {
if (bits == I2S_BITS_PER_SAMPLE_16BIT) {
return 0;
} else { // 32 bits
return 1;
}
} else { // STEREO
if (bits == I2S_BITS_PER_SAMPLE_16BIT) {
return 2;
} else { // 32 bits
return 3;
}
}
}
STATIC i2s_bits_per_sample_t get_dma_bits(uint8_t mode, i2s_bits_per_sample_t bits) {
if (mode == (I2S_MODE_MASTER | I2S_MODE_TX)) {
return bits;
} else { // Master Rx
// read 32 bit samples for I2S hardware. e.g. MEMS microphones
return I2S_BITS_PER_SAMPLE_32BIT;
}
}
STATIC i2s_channel_fmt_t get_dma_format(uint8_t mode, format_t format) {
if (mode == (I2S_MODE_MASTER | I2S_MODE_TX)) {
if (format == MONO) {
return I2S_CHANNEL_FMT_ONLY_LEFT;
} else { // STEREO
return I2S_CHANNEL_FMT_RIGHT_LEFT;
}
} else { // Master Rx
// read stereo frames for all I2S hardware
return I2S_CHANNEL_FMT_RIGHT_LEFT;
}
}
STATIC uint32_t get_dma_buf_count(uint8_t mode, i2s_bits_per_sample_t bits, format_t format, int32_t ibuf) {
// calculate how many DMA buffers need to be allocated
uint32_t dma_frame_size_in_bytes =
(get_dma_bits(mode, bits) / 8) * (get_dma_format(mode, format) == I2S_CHANNEL_FMT_RIGHT_LEFT ? 2: 1);
uint32_t dma_buf_count = ibuf / (DMA_BUF_LEN_IN_I2S_FRAMES * dma_frame_size_in_bytes);
return dma_buf_count;
}
STATIC uint32_t fill_appbuf_from_dma(machine_i2s_obj_t *self, mp_buffer_info_t *appbuf) {
// copy audio samples from DMA memory to the app buffer
// audio samples are read from DMA memory in chunks
// loop, reading and copying chunks until the app buffer is filled
// For asyncio mode, the loop will make an early exit if DMA memory becomes empty
// Example:
// a MicroPython I2S object is configured for 16-bit mono (2 bytes per audio sample).
// For every frame coming from DMA (8 bytes), 2 bytes are "cherry picked" and
// copied to the supplied app buffer.
// Thus, for every 1 byte copied to the app buffer, 4 bytes are read from DMA memory.
// If a 8kB app buffer is supplied, 32kB of audio samples is read from DMA memory.
uint32_t a_index = 0;
uint8_t *app_p = appbuf->buf;
uint8_t appbuf_sample_size_in_bytes = (self->bits / 8) * (self->format == STEREO ? 2: 1);
uint32_t num_bytes_needed_from_dma = appbuf->len * (I2S_RX_FRAME_SIZE_IN_BYTES / appbuf_sample_size_in_bytes);
while (num_bytes_needed_from_dma) {
size_t num_bytes_requested_from_dma = MIN(sizeof(self->transform_buffer), num_bytes_needed_from_dma);
size_t num_bytes_received_from_dma = 0;
TickType_t delay;
if (self->io_mode == ASYNCIO) {
delay = 0; // stop i2s_read() operation if DMA memory becomes empty
} else {
delay = portMAX_DELAY; // block until supplied buffer is filled
}
esp_err_t ret = i2s_read(
self->i2s_id,
self->transform_buffer,
num_bytes_requested_from_dma,
&num_bytes_received_from_dma,
delay);
check_esp_err(ret);
// process the transform buffer one frame at a time.
// copy selected bytes from the transform buffer into the user supplied appbuf.
// Example:
// a MicroPython I2S object is configured for 16-bit mono. This configuration associates to
// a frame map index of 0 = { 6, 7, -1, -1, -1, -1, -1, -1 } in the i2s_frame_map array
// This mapping indicates:
// appbuf[x+0] = frame[6]
// appbuf[x+1] = frame[7]
// frame bytes 0-5 are not used
uint32_t t_index = 0;
uint8_t f_index = get_frame_mapping_index(self->bits, self->format);
while (t_index < num_bytes_received_from_dma) {
uint8_t *transform_p = self->transform_buffer + t_index;
for (uint8_t i = 0; i < I2S_RX_FRAME_SIZE_IN_BYTES; i++) {
int8_t t_to_a_mapping = i2s_frame_map[f_index][i];
if (t_to_a_mapping != -1) {
*app_p++ = transform_p[t_to_a_mapping];
a_index++;
}
t_index++;
}
}
num_bytes_needed_from_dma -= num_bytes_received_from_dma;
if ((self->io_mode == ASYNCIO) && (num_bytes_received_from_dma < num_bytes_requested_from_dma)) {
// Unable to fill the entire app buffer from DMA memory. This indicates all DMA RX buffers are empty.
// Clear the I2S event queue so ioctl() indicates that the I2S object cannot currently
// supply more audio samples
xQueueReset(self->i2s_event_queue);
break;
}
}
return a_index;
}
STATIC size_t copy_appbuf_to_dma(machine_i2s_obj_t *self, mp_buffer_info_t *appbuf) {
if ((self->bits == I2S_BITS_PER_SAMPLE_32BIT) && (self->format == STEREO)) {
swap_32_bit_stereo_channels(appbuf);
}
size_t num_bytes_written = 0;
TickType_t delay;
if (self->io_mode == ASYNCIO) {
delay = 0; // stop i2s_write() operation if DMA memory becomes full
} else {
delay = portMAX_DELAY; // block until supplied buffer is emptied
}
esp_err_t ret = i2s_write(self->i2s_id, appbuf->buf, appbuf->len, &num_bytes_written, delay);
check_esp_err(ret);
if ((self->io_mode == ASYNCIO) && (num_bytes_written < appbuf->len)) {
// Unable to empty the entire app buffer into DMA memory. This indicates all DMA TX buffers are full.
// Clear the I2S event queue so ioctl() indicates that the I2S object cannot currently
// accept more audio samples
xQueueReset(self->i2s_event_queue);
// Undo the swap transformation as the buffer has not been completely emptied.
// The asyncio stream writer will use the same buffer in a future write call.
if ((self->bits == I2S_BITS_PER_SAMPLE_32BIT) && (self->format == STEREO)) {
swap_32_bit_stereo_channels(appbuf);
}
}
return num_bytes_written;
}
// FreeRTOS task used for non-blocking mode
STATIC void task_for_non_blocking_mode(void *self_in) {
machine_i2s_obj_t *self = (machine_i2s_obj_t *)self_in;
non_blocking_descriptor_t descriptor;
for (;;) {
if (xQueueReceive(self->non_blocking_mode_queue, &descriptor, portMAX_DELAY)) {
if (descriptor.direction == I2S_TX_TRANSFER) {
copy_appbuf_to_dma(self, &descriptor.appbuf);
} else { // RX
fill_appbuf_from_dma(self, &descriptor.appbuf);
}
mp_sched_schedule(descriptor.callback, MP_OBJ_FROM_PTR(self));
}
}
}
STATIC void mp_machine_i2s_init_helper(machine_i2s_obj_t *self, mp_arg_val_t *args) {
// are Pins valid?
int8_t sck = args[ARG_sck].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_sck].u_obj);
int8_t ws = args[ARG_ws].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_ws].u_obj);
int8_t sd = args[ARG_sd].u_obj == MP_OBJ_NULL ? -1 : machine_pin_get_id(args[ARG_sd].u_obj);
// is Mode valid?
i2s_mode_t mode = args[ARG_mode].u_int;
if ((mode != (I2S_MODE_MASTER | I2S_MODE_RX)) &&
(mode != (I2S_MODE_MASTER | I2S_MODE_TX))) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid mode"));
}
// is Bits valid?
i2s_bits_per_sample_t bits = args[ARG_bits].u_int;
if ((bits != I2S_BITS_PER_SAMPLE_16BIT) &&
(bits != I2S_BITS_PER_SAMPLE_32BIT)) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid bits"));
}
// is Format valid?
format_t format = args[ARG_format].u_int;
if ((format != STEREO) &&
(format != MONO)) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid format"));
}
// is Rate valid?
// Not checked: ESP-IDF I2S API does not indicate a valid range for sample rate
// is Ibuf valid?
// Not checked: ESP-IDF I2S API will return error if requested buffer size exceeds available memory
self->sck = sck;
self->ws = ws;
self->sd = sd;
self->mode = mode;
self->bits = bits;
self->format = format;
self->rate = args[ARG_rate].u_int;
self->ibuf = args[ARG_ibuf].u_int;
self->callback_for_non_blocking = MP_OBJ_NULL;
self->i2s_event_queue = NULL;
self->non_blocking_mode_queue = NULL;
self->non_blocking_mode_task = NULL;
self->io_mode = BLOCKING;
i2s_config_t i2s_config;
i2s_config.communication_format = I2S_COMM_FORMAT_STAND_I2S;
i2s_config.mode = mode;
i2s_config.bits_per_sample = get_dma_bits(mode, bits);
i2s_config.channel_format = get_dma_format(mode, format);
i2s_config.sample_rate = self->rate;
i2s_config.intr_alloc_flags = ESP_INTR_FLAG_LOWMED;
i2s_config.dma_desc_num = get_dma_buf_count(mode, bits, format, self->ibuf);
i2s_config.dma_frame_num = DMA_BUF_LEN_IN_I2S_FRAMES;
i2s_config.use_apll = false;
i2s_config.tx_desc_auto_clear = true;
i2s_config.fixed_mclk = 0;
i2s_config.mclk_multiple = I2S_MCLK_MULTIPLE_256;
i2s_config.bits_per_chan = 0;
// I2S queue size equals the number of DMA buffers
check_esp_err(i2s_driver_install(self->i2s_id, &i2s_config, i2s_config.dma_desc_num, &self->i2s_event_queue));
// apply low-level workaround for bug in some ESP-IDF versions that swap
// the left and right channels
// https://github.com/espressif/esp-idf/issues/6625
#if CONFIG_IDF_TARGET_ESP32S3
REG_SET_BIT(I2S_TX_CONF_REG(self->i2s_id), I2S_TX_MSB_SHIFT);
REG_SET_BIT(I2S_TX_CONF_REG(self->i2s_id), I2S_RX_MSB_SHIFT);
#else
REG_SET_BIT(I2S_CONF_REG(self->i2s_id), I2S_TX_MSB_RIGHT);
REG_SET_BIT(I2S_CONF_REG(self->i2s_id), I2S_RX_MSB_RIGHT);
#endif
i2s_pin_config_t pin_config;
pin_config.mck_io_num = I2S_PIN_NO_CHANGE;
pin_config.bck_io_num = self->sck;
pin_config.ws_io_num = self->ws;
if (mode == (I2S_MODE_MASTER | I2S_MODE_RX)) {
pin_config.data_in_num = self->sd;
pin_config.data_out_num = I2S_PIN_NO_CHANGE;
} else { // TX
pin_config.data_in_num = I2S_PIN_NO_CHANGE;
pin_config.data_out_num = self->sd;
}
check_esp_err(i2s_set_pin(self->i2s_id, &pin_config));
}
STATIC machine_i2s_obj_t *mp_machine_i2s_make_new_instance(mp_int_t i2s_id) {
if (i2s_id < 0 || i2s_id >= I2S_NUM_AUTO) {
mp_raise_ValueError(MP_ERROR_TEXT("invalid id"));
}
machine_i2s_obj_t *self;
if (MP_STATE_PORT(machine_i2s_obj)[i2s_id] == NULL) {
self = m_new_obj_with_finaliser(machine_i2s_obj_t);
self->base.type = &machine_i2s_type;
MP_STATE_PORT(machine_i2s_obj)[i2s_id] = self;
self->i2s_id = i2s_id;
} else {
self = MP_STATE_PORT(machine_i2s_obj)[i2s_id];
machine_i2s_deinit(self);
}
return self;
}
STATIC void mp_machine_i2s_deinit(machine_i2s_obj_t *self) {
i2s_driver_uninstall(self->i2s_id);
if (self->non_blocking_mode_task != NULL) {
vTaskDelete(self->non_blocking_mode_task);
self->non_blocking_mode_task = NULL;
}
if (self->non_blocking_mode_queue != NULL) {
vQueueDelete(self->non_blocking_mode_queue);
self->non_blocking_mode_queue = NULL;
}
self->i2s_event_queue = NULL;
}
STATIC void mp_machine_i2s_irq_update(machine_i2s_obj_t *self) {
if (self->io_mode == NON_BLOCKING) {
// create a queue linking the MicroPython task to a FreeRTOS task
// that manages the non blocking mode of operation
self->non_blocking_mode_queue = xQueueCreate(1, sizeof(non_blocking_descriptor_t));
// non-blocking mode requires a background FreeRTOS task
if (xTaskCreatePinnedToCore(
task_for_non_blocking_mode,
"i2s_non_blocking",
I2S_TASK_STACK_SIZE,
self,
I2S_TASK_PRIORITY,
(TaskHandle_t *)&self->non_blocking_mode_task,
MP_TASK_COREID) != pdPASS) {
mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("failed to create I2S task"));
}
} else {
if (self->non_blocking_mode_task != NULL) {
vTaskDelete(self->non_blocking_mode_task);
self->non_blocking_mode_task = NULL;
}
if (self->non_blocking_mode_queue != NULL) {
vQueueDelete(self->non_blocking_mode_queue);
self->non_blocking_mode_queue = NULL;
}
}
}
MP_REGISTER_ROOT_POINTER(struct _machine_i2s_obj_t *machine_i2s_obj[I2S_NUM_AUTO]);
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