I2S - can wroom be slave and receive pcm data?

[colinz]

I'm new to I2S and there is not much information about how to set it as slave and receive pcm data. What i've tried is two esp32 S3-wroom as i2s master and slave based on the official I2S example > FullDuplex, if i change the communication_format to I2S_COMM_FORMAT_I2S, the slave's serial will print a serials of "0", its not what i sent but it's another problem. But if i change both master and slave to I2S_COMM_FORMAT_STAND_PCM_SHORT, the slave will not print at all. Is there other thing i need to do to receive PCM data? I only wired bck, ws, and data in or out three lines, the mclk is floating. The slave code is like:

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1. #include "driver/i2s.h"
2.  
3. i2s_config_t i2s_config = {
4.   .mode = (i2s_mode_t)(I2S_MODE_SLAVE | I2S_MODE_TX | I2S_MODE_RX),
5.   .sample_rate = 8000,
6.   .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
7.   .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
8.   .communication_format = I2S_COMM_FORMAT_STAND_PCM_SHORT,
9.   .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
10.   .dma_buf_count = 8,
11.   .dma_buf_len = 256,
12.   .use_apll = true,
13. };
14.  
15. i2s_pin_config_t pin_config = {
16.   .bck_io_num = 4,
17.   .ws_io_num = 5,
18.   .data_out_num = 7,
19.   .data_in_num = 6
20. };
21.  
22. uint16_t rxbuf[256];
23. size_t readsize = 0;
24.  
25. void setup(){
26.   i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
27.   i2s_set_pin(I2S_NUM_0, &pin_config);
28.   Serial.begin(115200);
29. }
30.  
31. void loop(){
32.   readsize=0;
33.   i2s_read(I2S_NUM_0, &rxbuf[0], 3, &readsize, 100);
34.   if(readsize > 0){
35.     for(int i = 0; i < readsize; i++){
36.       Serial.print(rxbuf[i]);
37.       Serial.print(" ");
38.     }
39.     Serial.println();
40.   }
41. }

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