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M0A21/M0A23 Series
May 06, 2022
Page
563
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
of the preceding transaction word and the first clock edge of the following transaction word. The default
value is 0x3. The period of the suspend interval is obtained according to the following equation.
(SUSPITV[3:0] + 0.5) * period of SPI_CLK clock cycle
Example:
SUSPITV = 0x0 … 0.5 SPI_CLK clock cycle.
SUSPITV = 0x1 … 1.5 SPI_CLK clock cycle.
……
SUSPITV = 0xE … 14.5 SPI_CLK clock cycle.
SUSPITV = 0xF … 15.5 SPI_CLK clock cycle.
Note:
Master only
[7:6]
SCLKMODE
Serial Bus Clock Mode
This bit field defines the SCLK idle status, data transmit, and data receive edge.
MODE0 = The idle state of SPI clock is low level. Data is transmitted with falling edge and received with
rising edge.
MODE1 = The idle state of SPI clock is low level. Data is transmitted with rising edge and received with
falling edge.
MODE2 = The idle state of SPI clock is high level. Data is transmitted with rising edge and received with
falling edge.
MODE3 = The idle state of SPI clock is high level. Data is transmitted with falling edge and received with
rising edge.
[5:4]
Reserved
Reserved.
[3]
AUTOSS
Automatic Slave Select Function Enable
0 = Slave select signal will be controlled by the setting value of SS (USPI_PROTCTL[2]) bit.
1 = Slave select signal will be generated automatically. The slave select signal will be asserted by the SPI
controller when transmit/receive is started, and will be de-asserted after each transmit/receive is finished.
Note:
Master only
[2]
SS
Slave Select Control
If AUTOSS bit is cleared, setting this bit to 1 will set the slave select signal to active state, and setting this
bit to 0 will set the slave select back to inactive state.
If the AUTOSS function is enabled (AUTOSS = 1), the setting value of this bit will not affect the current state
of slave select signal.
Note:
In SPI protocol, the internal slave select signal is active high.
Note:
Master only
[1]
SLV3WIRE
Slave 3-wire Mode Selection
The SPI protocol can work with 3-wire interface (without slave select signal) in Slave mode.
0 = 4-wire bi-direction interface.
1 = 3-wire bi-direction interface.
Note:
Slave only
[0]
SLAVE
Slave Mode Selection
0 = Master mode.
1 = Slave mode.