kewalmshah
commented
6 years ago Hi @FlorisColpaert can you please test the output data from microphone first ? I have a sample code tested and works fine with PDM microphones.
/* I2S PDM example */
#include <stdio.h>
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2s.h"
#include "esp_system.h"
#include "esp_spi_flash.h"
#include "rom/spi_flash.h"
#define SAMPLE_RATE 16000
#define BITS_PS 16
#define I2S_NUM 0
#define BUF_COUNT 4
#define BUF_LENGTH 250
/*
* In PDM mode the clock is generated on WS line. Fwsclk = 64*(sample frequency)
* Here sample frequuency is 8KHz, hence WS clk frequency will be 64*8k = 512KHz
* Each sector of flash is 4096 bytes
*/
int16_t samples_data[SPI_FLASH_SEC_SIZE / 2] = {0}; //Since each sample is 2 bytes
void app_main()
{
i2s_config_t i2s_config = {
.mode = I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_PDM, //master, RX, PDM
.sample_rate = SAMPLE_RATE,
.bits_per_sample = BITS_PS,
.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
.communication_format = I2S_COMM_FORMAT_I2S, //pcm data format
.dma_buf_count = BUF_COUNT,
.dma_buf_len = BUF_LENGTH,
.use_apll = 0, //apll disabled
.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1 //interrupt level 1(lowest priority)
};
i2s_pin_config_t pin_config = {
.ws_io_num = GPIO_NUM_19,
.data_in_num = GPIO_NUM_35,
};
i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
i2s_set_pin(I2S_NUM, &pin_config);
printf("Start speaking\n");
vTaskDelay(1000/portTICK_PERIOD_MS);
/*
* Steps to follow:
* 1. erase each sector
* 2. read data from PDM mics
* 3. write to flash
*/
for (uint32_t base_addr = 0x300000; base_addr < 0x400000; base_addr += SPI_FLASH_SEC_SIZE) {
printf("erasing sector %x\n", base_addr / SPI_FLASH_SEC_SIZE);
spi_flash_erase_sector(base_addr / SPI_FLASH_SEC_SIZE);
i2s_read_bytes(I2S_NUM, (const char*)samples_data, SPI_FLASH_SEC_SIZE, portMAX_DELAY);
printf("writing at %x\n", base_addr);
spi_flash_write(base_addr, samples_data, sizeof(samples_data));
printf("done at %x\n", base_addr);
}
printf("Done writing data to flash\n");
}Please follow these steps to test PDM mic output.
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Flash the attached test code and start speaking so that PDM mic can record your voice and store the sample data into flash.
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Note the base address for flash and size of the sample data(in our test code size is 0x100000 and start address is 0x300000).
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Run following commands: A. cd ~/esp-idf/components/esptool_py/esptool/ B. python esptool.py --chip esp32 --port /dev/ttyUSB3 --baud 1152000 read_flash 0x300000 0x100000 ~/test.pcm python esptool.py --chip esp32 --port [port name] --baud [baud rate] read_flash [start address] [size] [file name and location] Now you have stored the recorded mic data in file test.pcm
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Now play the recorded pcm data on your computer using following command: aplay -f S16_LE -c2 -r16000 test.pcm aplay -f [signed 16 little endian] -[stereo] -r[sample rate] [file name] Now you can listen to the recorded data.
FlorisColpaert
Piocky
faaltunel
phorenabess
giPeteR
anhnhancao
Hey, I have issue's using the INMP621 microphone with PDM.. I can't get correct data from it to calculate the noise level(dB). When there is no special sound. The data is always around 976 and doesn't gets to a negative value. I do se change when i make some noice, but i don't think it's relevant. The sound level only changes like 0.01db.
Does anyone see some major errors I made?
i2s_config_t i2s_config = { .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_PDM), .sample_rate = 44100, .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT, .channel_format = I2S_CHANNEL_FMT_ONLY_RIGHT, .communication_format = (i2s_comm_format_t)(I2S_COMM_FORMAT_PCM ), .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1, // lowest interrupt priority .dma_buf_count = 8, .dma_buf_len = 68, .use_apll = 0 };
// // Clock is internal // // No data out i2s_pin_config_t pinConfig = { .bck_io_num = I2S_PIN_NO_CHANGE, .ws_io_num = clkOut->GetPin(), // WS is connected to clock for external clock .data_out_num = I2S_PIN_NO_CHANGE, .data_in_num = pinRx->GetPin() // Data input of mic };
i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL); //install and start i2s driver i2s_set_pin(I2S_NUM_0, &pinConfig);
.....
while ((readcount < 8000)) { if ( (i2s_pop_sample(I2S_NUM_0, (char *)&sample, (TickType_t)portMAXDELAY)) >= 2) { // sample = ((sampleBfr[1] << 8 & 0xFF00) + (sampleBfr[0] & 0x00ff)); rms += pow((double)sample/32767, 2); readcount++; } }
if( readcount >= 8000) { double db; if (rms != 0){ db = 20*log10(sqrt((double)rms/(readcount))); } else db = 0;
successHandler((float)db);
}else{ failHandler(); }