USART Operation: SPI Mode

15-8 USART Peripheral Interface, SPI Mode

Receive Enable

The SPI receive enable state diagrams are shown in Figure 156 and

Figure 157. When USPIEx = 0, UCLK is disabled from shifting data into the

RX shift register.

Figure 156. SPI Master Receive-Enable State Diagram
Idle State
(Receiver
Enabled)
Receive
Disable
Receiver
Collects
Character
USPIEx = 0 No Data Written
to UxTXBUF Not Completed
USPIEx = 1
USPIEx = 0
USPIEx = 1 Handle Interrupt
Conditions
Character
Received
USPIEx = 1
USPIEx = 0
SWRST
PUC
Data Written
to UxTXBUF
Figure 157. SPI Slave Receive-Enable State Diagram
Idle State
(Receive
Enabled)
Receive
Disable
Receiver
Collects
Character
USPIEx = 0 No Clock at UCLK Not Completed
USPIEx = 1
USPIEx = 0
USPIEx = 1 Handle Interrupt
Conditions
Character
Received
USPIEx = 1
USPIEx = 0
SWRST
PUC
External Clock
Present