Posted on May 17, 2011 at 13:07I am trying to use a STM32F103ZE to get data from a CODEC via the I2S interface with 24 bits data.
This is the init sequence :
Code:
I2S_InitStructure.I2S_Mode = I2S_Mode_MasterRx;
I2S_InitStructure.I2S_Standard = I2S_Standard_Phillips;
I2S_InitStructure.I2S_DataFormat = I2S_DataFormat_24b;
I2S_InitStructure.I2S_MCLKOutput = I2S_MCLKOutput_Enable;
I2S_InitStructure.I2S_AudioFreq = I2S_AudioFreq_16k;
I2S_InitStructure.I2S_CPOL = SPI_CPOL_Low;
I2S_Init(SPI2, &I2S_InitStructure);
and the read sequence :
Code:
for (i=0; i<sizeof(buffer)/sizeof(u32); i++)
{
while(SPI_I2S_GetFlagStatus(SPI2,SPI_I2S_FLAG_RXNE)==RESET)
;
buffer[i] = SPI_I2S_ReceiveData(SPI2) << 16;
while(SPI_I2S_GetFlagStatus(SPI2,SPI_I2S_FLAG_RXNE)==RESET)
;
buffer[i] |= SPI_I2S_ReceiveData(SPI2);
}
This is an example of the data I get :
0xFFFCA9FF
0xFFC1A200
0x0006E9FF
0xFEB01A00
0xFFF6D000
...
According to the STM32 Ref Manual, page 549 (Figure 213),
the 8 LSB should be cleared. They are not ...
Am I doing something wrong, or is it a bug in the STM32 I2S implementation ?
