19.4.2.5.2 Left Justified Mode
The Left Justified mode is similar to I2S mode, however, in this mode, the SPI shifts the audio data’s MSb on the first SCKx edge that is coincident with an LRCK transition. On the receiver side, the SPI module samples the MSb on the next SCKx edge.
In general, a codec using justified protocols defaults to transmitting data on the rising edge of SCKx and receiving data on the falling edge of SCKx.
- Required Configuration Settings
To set the module to Left Justified mode, the following bits must to be set:
- AUDMOD[1:0] =
01(SPIxCON1[25:24]) - FRMPOL =
1(SPIxCON1[21]) - CKP =
0(SPIxCON1[6])
- AUDMOD[1:0] =
This enables the SDOx and LRCK transitions to occur on the rising edge of SCKx. Refer to the sample waveform diagrams shown in Figure 19-23 and Figure 19-24 for 16, 24 and 32-bit audio data transfers.
