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Rev. 1.00
449 of 576
January 28, 2022
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F54231/HT32F54241/HT32F54243/HT32F54253
21 Serial Peripheral Interface (SPI)
21 Serial Peripheral Interface (SPI)
CPOL = 1, CPHA = 0
In this format, the received data is sampled on the SCK line falling edge while the transmitted
data is changed on the SCK line rising edge. In the master mode, the first bit is driven when data
is written into the SPIDR register. In the slave mode, the first bit is driven when the SEL signal
changes to an active level. The accompanying figure shows the single byte transfer timing of this
format.
SCK
MISO
MOSI
TX[7]
TX[6]
TX[5]
TX[4]
TX[3]
TX[2]
TX[1]
TX[0]
RX[7]
RX[6]
RX[5]
RX[4]
RX[3]
RX[2]
RX[1]
½ SCK
SEL (SELAP=0)
SEL (SELAP=1)
RX[0]
Data sampled
Figure 159. SPI Single Byte Transfer Timing Diagram – CPOL = 1, CPHA = 0
The accompanying figure shows the continuous data transfer timing of this format. Note that the
SEL signal must change to an inactive level between each data frame.
SCK
SEL (SELAP=0)
SEL (SELAP=1)
Data1
Data2
MOSI/MISO
½ SCK
½ SCK
Figure 160. SPI Continuous Transfer Timing Diagram – CPOL = 1, CPHA = 0