A control bit MODE16 (SPIxCON<10>) allows the module to communicate in either 8-bit or 16-bit modes. The functionality will be the same for each mode except the number of bits that are received and transmitted. The following should be noted in this context:
The module is reset when the value of the MODE16 control bit is changed. Consequently, the bit should not be changed during normal operation.
Data are transmitted out of bit 7 of the shift register SPIxSR for 8-bit operation and out of bit 15 for 16-bit operation. In both modes data are shifted into bit ‘0’ of the SPIxSR.
8 clock pulses at the SCKx pin are required to shift in/out data in 8 bit mode, while 16 clock pulses are required in the 16-bit mode.