AT89LP2052 datasheet(45/90 Pages) ATMEL

45 / 90 page

3547F–MICRO–6/06

AT89LP2052/LP4052

Figure 18-4. SPI Transfer Format with CPHA = 0

Note:

*Not defined but normally MSB of character just received

Figure 18-5. SPI Transfer Format with CPHA = 1

Note:

*Not defined but normally LSB of previously transmitted character

18.4

SPI Pin Configuration

Before using the Serial Peripheral Interface the four SPI pins – SCK, MISO, MOSI and SS –

must be properly configured for the desired functionality. See Section 14.7 “Port Alternate Func-

tions” on page 20. When the SPI is in Master mode, SCK and MOSI must be configured as

bidirectional or output, with P1.7 and P1.5 set to “1”. MISO should be input-only, or bidirectional

with P1.6 set to “1”. When the SPI is in Slave mode, SCK, MOSI and SS must be configured as

input-only, or as bidirectional with P1.7, P1.6 and P1.4 set to “1”. MISO should be set as bidirec-

tional or output, with P1.6 set to “1”. If all four pins are set as bidirectional and their respectively

port bits are all “1”, it is possible to switch between Master and Slave mode without reconfiguring

the pins.

MSB

LSB

MSB

LSB

SCK CYCLE #

(FOR REFERENCE)

SCK (CPOL = 0)

SCK (CPOL = 1)

MOSI

(FROM MASTER)

MISO

(FROM SLAVE)

SS (TO SLAVE)

AT89LP2052 Datasheet(PDF) 45 Page - ATMEL Corporation