The I2SC user interface includes a Receive Holding Register (I2SC_RHR) and a Transmit Holding Register (I2SC_THR). These registers are used to access audio samples for both audio channels.
When a new data word is available in I2SC_RHR, the Receive Ready bit (RXRDY) in I2SC_SR is set. Reading I2SC_RHR clears this bit.
A receive overrun condition occurs if a new data word becomes available before the previous data word has been read from I2SC_RHR. In this case, the Receive Overrun bit in I2SC_SR and bit i of the RXORCH field in I2SC_SR are set, where i is the current receive channel number.
When I2SC_THR is empty, the Transmit Ready bit (TXRDY) in I2SC_SR is set. Writing to I2SC_THR clears this bit.
A transmit underrun condition occurs if a new data word needs to be transmitted before it has been written to I2SC_THR. In this case, the Transmit Underrun (TXUR) bit and bit i of the TXORCH field in I2SC_SR are set, where i is the current transmit channel number. If the TXSAME bit in I2SC_MR is ’0’, then a zero data word is transmitted in case of underrun. If I2SC_MR.TXSAME is ’1’, then the previous data word for the current transmit channel number is transmitted.
Data words are right-justified in I2SC_RHR and I2SC_THR. For the 16-bit compact stereo data format, the left sample uses bits 15:0 and the right sample uses bits 31:16 of the same data word. For the 8-bit compact stereo data format, the left sample uses bits 7:0 and the right sample uses bits 15:8 of the same data word.