AT32F425
Series Reference Manual
2022.03.30
Page 171
Ver 2.01
FBN=0: 8-bit frame
Slave transmit: 0xaa, 0xcc, 0xaa
Figure 13-10 Slave half-duplex transmit
BF flag
SCK
CS
MISO
1
0
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
0
0
0
TDBE flag
Drive
Transmit buffer empty and
software can write data
Half-duplex communication – master receive
Configured as follows:
MSTEN=1: Master enable
SLBEN=1: Single line bidirectional mode
SLBTD=0: Receive enable
CLKPOL=0, CLKPHA=0: SCK idle output low, use the first edge for sampling
FBN=0: 8-bit frame
Master receive: 0xaa, 0xcc, 0xaa
Figure 13-11 Master half-duplex receive
SCK
BF flag
CS
MOSI
1
0
1
1
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
0
0
0
BF flag remains low
RDBF flag
Sampling
Software needs to read the
received data
13.2.11 TI mode
The SPI interface supports TI mode. The TIEN bit can be set to enable SPI TI mode.
In TI mode, a bit of different is present between continouous and discontinuous communication timings.
When the to-be transmitted data is written before the rising SCK edge corresponding to the last data
of the current transmit frame, it it a continuous communication, without dummy CLK between data, and
the host sends a valid CS pulse while transmitting the last data of the current frame.
Figure 13-12 TI mode continous transfer
SCK
MISO
CS
MOSI
MSB
LSB MSB
LSB
When the to-be-transmitted data is written between the rising and falling SCK edge corresponding to
the last data of the current transmit frame, a dummy CLK exists between data.