An ESP32-specific workaround has been circulated online. I have found a similar workaround for the ESP32-S3. The code below simply modifies the I2S RX registers to delay reading serial data by falling edge of the clock line, and subsequently force Philips mode.
There may be a better way to do this, but this is what worked for me. Hope this helps someone!
Code: sph0645.ino Select all
#include <driver/i2s.h>
#include <soc/i2s_reg.h>
#define BUF_LEN 2048
#define SAMPLE_RATE 44100
#define I2S_PORT I2S_NUM_0
#define DATA_PIN 7
#define BCLK_PIN 4
#define WS_PIN 17
void setup() {
Serial.begin(115200);
const i2s_config_t micCfg = {
.mode = i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_RX),
.sample_rate = SAMPLE_RATE,
.bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,
.channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
// My microphone is configured to send on the right channel.
// A bug in ESP-IDF swaps the two, so this is set to left.
// See https://github.com/espressif/esp-idf/issues/6625
.communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_STAND_I2S),
.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
.dma_buf_count = 8,
.dma_buf_len = 1024,
.use_apll = false,
.tx_desc_auto_clear = false,
.fixed_mclk = 0,
};
i2s_pin_config_t micPins = {
.bck_io_num = BCLK_PIN,
.ws_io_num = WS_PIN,
.data_out_num = -1,
.data_in_num = DATA_PIN,
};
esp_err_t err;
err = i2s_driver_install(I2S_PORT, &micCfg, 0, NULL);
if (err != ESP_OK) {
Serial.println("I2S driver initialization failed");
while (true);
}
// Delay by falling edge
REG_SET_BIT(I2S_RX_TIMING_REG(I2S_PORT), BIT(1));
// Force Philips mode
REG_SET_BIT(I2S_RX_CONF1_REG(I2S_PORT), I2S_RX_MSB_SHIFT);
err = i2s_set_pin(I2S_PORT, &micPins);
if (err != ESP_OK) {
Serial.println("Setting pins failed");
while (true);
}
}
void loop() {
static int32_t buf32[BUF_LEN];
static int16_t buf16[BUF_LEN];
size_t bytesRead;
esp_err_t err = i2s_read(I2S_PORT, (uint8_t*) buf32, BUF_LEN*sizeof(int32_t), &bytesRead, portMAX_DELAY);
if (err != ESP_OK) {
Serial.println("Error reading from microphone");
Serial.println(err);
return;
}
size_t samplesRead = bytesRead / sizeof(int32_t);
for (int i=0; i<samplesRead; i++) {
// Discard unused lower 12 bits. Sign bit is already where it needs to be.
buf32[i] >>= 12;
buf16[i] = (int16_t) (buf32[i] & 0xFFFF);
}
// Do stuff with signed 16-bit little-endian samples.
}
