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Rev. 1.00
423 of 486
July 31, 2018
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F50231/HT32F50241
20 Serial Peripheral Interface (SPI)
Figure 154 shows the continuous data transfer timing diagram of this format. Note that the SEL
signal must change to an inactive level between each data frame.
SCK
SEL (SELAP=0)
Data1
Data2
MOSI/MISO
SEL (SELAP=1)
Figure 154. SPI Continuous Data Transfer Timing Diagram – CPOL = 0, CPHA = 0
CPOL = 0, CPHA = 1
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 at the first SCK clock rising
edge. Figure 155 shows the single data byte transfer timing.
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=1)
RX[0]
Data sampled
SEL(SELAP=0)
Figure 155. SPI Single Byte Transfer Timing Diagram – CPOL = 0, CPHA = 1