C8051F336/7/8/9
SFR Definition 23.1. SPI0CFG: SPI0 Configuration
Bit
7
6
5
4
3
2
1
0
SPIBSY
MSTEN
CKPHA
CKPOL
SLVSEL
NSSIN
SRMT
RXBMT
Name
Type
Reset
R
0
R/W
0
R/W
0
R/W
0
R
0
R
1
R
1
R
1
SFR Address = 0xA1
Bit
Name
Function
7
SPIBSY
SPI Busy.
This bit is set to logic 1 when a SPI transfer is in progress (master or slave mode).
6
5
4
3
MSTEN
CKPHA
CKPOL
SLVSEL
Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
SPI0 Clock Phase.
*
0: Data centered on first edge of SCK period.
1: Data centered on second edge of SCK period.
*
SPI0 Clock Polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
Slave Selected Flag.
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected
slave. It is cleared to logic 0 when NSS is high (slave not selected). This bit does
not indicate the instantaneous value at the NSS pin, but rather a de-glitched ver-
sion of the pin input.
2
1
NSSIN
SRMT
NSS Instantaneous Pin Input.
This bit mimics the instantaneous value that is present on the NSS port pin at the
time that the register is read. This input is not de-glitched.
Shift Register Empty (valid in slave mode only).
This bit will be set to logic 1 when all data has been transferred in/out of the shift
register, and there is no new information available to read from the transmit buffer
or write to the receive buffer. It returns to logic 0 when a data byte is transferred to
the shift register from the transmit buffer or by a transition on SCK. SRMT = 1 when
in Master Mode.
0
RXBMT
Receive Buffer Empty (valid in slave mode only).
This bit will be set to logic 1 when the receive buffer has been read and contains no
new information. If there is new information available in the receive buffer that has
not been read, this bit will return to logic 0. RXBMT = 1 when in Master Mode.
*Note: In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data on MISO is
sampled one SYSCLK before the end of each data bit, to provide maximum settling time for the slave device.
See Table 23.1 for timing parameters.
Rev. 0.2
181
SILICON [ SILICON ]
