AT83C5111 datasheet(38/86 Pages) ATMEL

38 / 86 page

AT8xC5111

4190A–8051–11/02

Figure 16 shows an SPI transmission in which CPHA is ’1’. In this case, the Master

begins driving its MOSI pin on the first SCK edge. Therefore the Slave uses the first

SCK edge as a start transmission signal. The SS pin can remain low between transmis-

sions (Figure 17). This format may be preferable in systems having only one Master and

only one Slave driving the MISO data line.

Figure 5. Data Transmission Format (CPHA = 1)

Figure 15 shows the first SCK edge is the MSB capture strobe. Therefore, the Slave

must begin driving its data before the first SCK edge, and a falling edge on the SS pin is

used to start the transmission. The SS pin must be toggled high and then low between

each byte transmitted (Figure 17).

Figure 6. CPHA/SS Timing

MSB

bit6

bit5

bit4

bit3

bit2

bit1

LSB

bit6

bit5

bit4

bit3

bit2

bit1

MSB

LSB

567

Capture Point

SS (to Slave)

MISO (from Slave)

MOSI (from Master)

SCK (CPOL = 1)

SCK (CPOL = 0)

SPEN (Internal)

SCK Cycle Number

Byte 1

Byte 2

Byte 3

MISO/MOSI

Master SS

Slave SS

(CPHA = 1)

Slave SS

(CPHA = 0)

AT83C5111 数据表(PDF) 38 Page - ATMEL Corporation

AT83C5111 数据表(HTML) 38 Page - ATMEL Corporation

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