Rainbow-electronics AT89C5132 Manual de usuario descargar pdf (Pagina 122)

122

AT8xC5132

4173A–8051–08/02

Figure 97. Data Transmission Format (CPHA = 0)

Figure 98. Data Transmission Format (CPHA = 1)

Management Figure 97 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 99). SPDAT must be loaded with data before SS

is asserted

again.

Figure 98 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 99).

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

(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

(to Slave)

Capture Point

1 2 ... 117 118 119 120 121 122 123 124 125 126 127 ... 161 162

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Rainbow-electronics AT89C5132 Manual de usuario Pagina 122