IIS frame start delay (units of SCLK/BCK periods)

[shehold]

I am now using IIS data, I want to know the clock problem of next frame synchronization, the external ADC is set to standard IIS format, VS1005 read and output data has been wrong (there is noise), my DAC frame synchronization data is set to 1.0 delay, which should be the standard IIS protocol. But I carefully read the IIS protocol description of VS1005, it seems to be 0 or 0.5 delay format, can 1005 change the IIS data alignment? How to change.

[shehold]

Another problem is that IIS in 32-bit mode, I read IIS on a 24bit data, the final read down value is what? For example: 0xFFFFFF(24BIT mode),

Code: Select all

 static s_int32 myBuf[2*BUFSIZE];
    fread(myBuf, sizeof(s_int32)*2, BUFSIZE, stdaudioin); //IIS INPUT 24BIT MODE value :0xFFFFFF
//What is the *myBuf value read out at this time
    fwrite(myBuf, sizeof(s_int32)*2, BUFSIZE, stdaudioout); //IIS OUTPUT 32BIT MODE, *myBuf = 0x00FFFFFF OR *myBuf = 0xFFFFFF00 ?

[pasi]

VS1005 I2S is always using the I2S format (one-bit delay to frame sync). If you have bit errors, maybe the data (or frame sync) is changing too close to the bit clock changing.

If fewer bits are sent, the data should be MSb-aligned, i.e. 0xffffff becomes 0xffffff00. (But I have not personally verified this.)