35.4.1 Client Mode Transmit Options

The SDO output of the SPI module in Client mode is controlled by the following:
  • TXR bit
  • TRIS bit associated with the SDO pin
  • Client Select input
  • Current state of the transmit FIFO
This control is summarized in the following table where TRISxn refers to the bit in the TRIS register corresponding to the pin that SDO has been assigned with PPS, TXR is the Transmit Data Required Control bit, SS is the state of the Client Select input, and TXBE is the transmit FIFO Buffer Empty bit.
Table 35-2. Client Mode Transmit
TRISxn(1)TXRSSTXBESDO State
00FALSE0Drives state determined by LATxn(2)
00FALSE1Drives state determined by LATxn(2)
00TRUE0

Outputs the oldest byte in the transmit
FIFO Does not remove data from the transmit FIFO

00TRUE1Outputs the most recently received byte
01FALSE0Drives state determined by LATxn(2)
01FALSE1Drives state determined by LATxn(2)
01TRUE0

Outputs the oldest byte in the transmit FIFO
Removes transmitted byte from the transmit FIFO
Decrements occupancy of transmit FIFO

01TRUE1

Outputs the most recently received byte
Sets the TXUIF bit

10FALSE0Tri-stated
10FALSE1Tri-stated
10TRUE0Tri-stated
10TRUE1Tri-stated
11FALSE0Tri-stated
11FALSE1Tri-stated
11TRUE0

Outputs the oldest byte in the transmit FIFO
Removes transmitted byte from the transmit FIFO
Decrements the FIFO occupancy

11TRUE1

Outputs the most recently received byte
Sets the TXUIF bit

Note:
  1. TRISxn is the bit in the TRISx register corresponding to the pin to which SDO has been assigned with PPS.
  2. LATxn is the bit in the LATx register corresponding to the pin to which SDO has been assigned with PPS.