After 8
Initial
Master SPI Shift
WordA
WordB
After 8
Initial
Slave SPI Shift Register
WordB
WordC
Shift Register
Transmitter Buffer
Control
Master
Receiver Register
Shift Register
Transmitter Buffer
Slave
(Transmit Only)
SPIDAT
SPICLK
SPIEN (Optional)
Control
(Single Line)
After 8
Initial
Master SPI Shift
WordA
WordC
After 8
Initial
Slave SPI Shift Register
WordB
WordA
Shift Register
Transmitter Buffer
Control
Master
Receiver Register
Shift Register
Slave
(Receive Only)
Receiver Register
SPIDAT
SPICLK
SPIEN (Optional)
Control
(Single Line)
Functional Description
24.3.1.2.1 Example With a Receive-Only Slave
shows a half duplex system with a Master device on the left and a receive-only Slave device
on the right. Each time a bit is transferred out from the Master, one bit is transferred in the Slave. After 8
cycles of the serial clock SPICLK, the 8-bit WordA has been transferred from the master to the slave.
Figure 24-4. SPI Half-Duplex Transmission (Receive-only Slave)
24.3.1.2.2 Example With a Transmit-Only Slave
shows a half duplex system with a Master device on the left and a transmit-only Slave device
on the right. Each time a bit is transferred out from the Slave, one bit is transferred in the Master. After 8
cycles of the serial clock SPICLK, the 8-bit WordA has been transferred from the slave to the master.
Figure 24-5. SPI Half-Duplex Transmission (Transmit-Only Slave)
3999
SPRUH73H – October 2011 – Revised April 2013
Multichannel Serial Port Interface (McSPI)
Copyright © 2011–2013, Texas Instruments Incorporated