LSB
D1
D2
D3
D4
D5
D6
MSB
D0
D1
D2
D3
D4
D5
D6
D7
Write SPIDAT
SPIx_CLK
SPIx_SIMO
SPIx_SOMI
Sample in
reception
Clock phase = 0 (SPIx_CLK without delay)
- Data is output on the rising edge of SPIx_CLK
- Input data is latched on the falling edge of SPIx_CLK
- A write to the SPIDAT regidter starts SPIx_CLK
Clock polarity = 0, Clock phase = 0
1
2
3
4
5
6
7
8
Architecture
1428
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Serial Peripheral Interface (SPI)
29.2.11.3 Clock Phase and Polarity
The SPI provides the flexibility to program four different clock mode combinations that SPIx_CLK may
operate, enabling a choice of the clock phase (delay or no delay) and the clock polarity (rising edge or
falling edge). When operating with PHASE active, the SPI makes the first bit of data available after
SPIDAT1 is written and before the first edge of SPIx_CLK. The data input and output edges depend on
the values of both the POLARITY and PHASE bits as shown in
Table 29-7. Clocking Modes
POLARITY
PHASE
Action
0
0
Data is output on the rising edge of SPIx_CLK. Input data is latched
on the falling edge.
0
1
Data is output one half-cycle before the first rising edge of SPIx_CLK
and on subsequent falling edges. Input data is latched on the rising
edge of SPIx_CLK.
1
0
Data is output on the falling edge of SPIx_CLK. Input data is latched
on the rising edge.
1
1
Data is output one half-cycle before the first falling edge of SPIx_CLK
and on subsequent rising edges. Input data is latched on the falling
edge of SPIx_CLK.
to
illustrate the four possible signals of SPIx_CLK corresponding to each mode.
Having four signal options allows the SPI to interface with different types of serial devices. Also shown are
the SPIx_CLK control bit polarity and phase values corresponding to each signal.
Figure 29-8. Clock Mode with POLARITY = 0 and PHASE = 0