Datasheet

120
AT89C5132
4173C–USB–07/04
Figure 96. Data Transmission Format (CPHA = 0)
Figure 97. Data Transmission Format (CPHA = 1)
SS
Management Figure 96 shows an SPI transmission with CPHA = 0, where the first SCK edge is the
MSB capture point. Therefore the slave starts to output its MSB as soon as it is
selected: SS
asserted to low level. SS must then be deasserted between each byte
transmission (see Figure 98). SPDAT must be loaded with data before SS
is asserted
again.
Figure 97 shows an SPI transmission with CPHA = 1, where the first SCK edge is used
by the slave as a start of transmission signal. Therefore SS
may remain asserted
between each byte transmission (see Figure 98).
1 2 3 4 5 6 7 8
MSB
bit 1 LSBbit 2bit 4 bit 3bit 6 bit 5
bit 1bit 2bit 4 bit 3bit 6 bit 5MSB LSB
MOSI (from Master)
MISO (from Slave)
SCK (CPOL = 1)
SCK (CPOL = 0)
SPEN (Internal)
SCK Cycle Number
SS
(to Slave)
to Capture Point
1 2 3 4 5 6 7 8
MSB bit 1 LSBbit 2bit 4 bit 3bit 6 bit 5
bit 1bit 2bit 4 bit 3bit 6 bit 5MSB LSB
MOSI (from Master)
MISO (from Slave)
SCK (CPOL = 1)
SCK (CPOL = 0)
SPEN (Internal)
SCK Cycle Number
SS
(to Slave)
Capture Point