GD32VF103 User Manual
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and goes low when transmission or reception process begins. When SPI is disabled, the NSS
goes high.
The application may also use a general purpose IO as NSS pin to realize more flexible NSS.
18.5.3.
SPI operating modes
Table 18-2. SPI operating modes
Mode
Description
Register configuration
Data pin usage
MFD
Master full-duplex
MSTMOD = 1
RO = 0
BDEN = 0
BDOEN: Don’t care
MOSI: Transmission
MISO: Reception
MTU
Master transmission with
unidirectional connection
MSTMOD = 1
RO = 0
BDEN = 0
BDOEN: Don’t care
MOSI: Transmission
MISO: Not used
MRU
Master reception with
unidirectional connection
MSTMOD = 1
RO = 1
BDEN = 0
BDOEN: Don’t care
MOSI: Not used
MISO: Reception
MTB
Master transmission with
bidirectional connection
MSTMOD = 1
RO = 0
BDEN = 1
BDOEN = 1
MOSI: Transmission
MISO: Not used
MRB
Master reception with
bidirectional connection
MSTMOD = 1
RO = 0
BDEN = 1
BDOEN = 0
MOSI: Reception
MISO: Not used
SFD
Slave full-duplex
MSTMOD = 0
RO = 0
BDEN = 0
BDOEN: Don’t care
MOSI: Reception
MISO: Transmission
STU
Slave transmission with
unidirectional connection
MSTMOD = 0
RO = 0
BDEN = 0
BDOEN: Don’t care
MOSI: Not used
MISO: Transmission
SRU
Slave reception with
unidirectional connection
MSTMOD = 0
RO = 1
BDEN = 0
BDOEN: Don’t care
MOSI: Reception
MISO: Not used
STB
Slave transmission with
bidirectional connection
MSTMOD = 0
RO = 0
MOSI: Not used
MISO: Transmission