SPI —

SPI

SPI(Serial Peripheral Interfacer ) SPI RAM EEPROM FlashROM A D D A LED LED I O UART SPI I O SPI I O

AT89C205l SPI EEPROM 93CA6 1 I O SPI

93C46 SPI

93CA6 SPI 4 I O (SK) DO DI CS (MSB) (LsB) 93C46 SPI 2

SPI

SPI AT89C2051 SPI 1 AT89C2051 EEPROM 93C46 P1 0 SPI SDO P1 2 SPI SCK P1 3 SPI SCS P1 1 SPI SDI

P1 2(SCK) 0( )

AT89C2051 P1 0 1 (1) 2 (10) 6 (A5A4A3A2A1A0) P1 1 1 (0) l6 ( )

AT89C2051 P1 0 1 (1) 2 (01) 6 (A5A4A3A2A1A0) P1 0 l6 ( )

(WEN)) 1 (1) 2 (00) 6 (11XXXX)

(WDS)) 1 (1) 2 (00) 6 (00XXXX)

C51 SPI

// I/O

sbit SDO=P1^0

sbit SDI=P1^1

sbit SCK=P1^ 2

sbit SCS=P1^3

sbit ACC_7= ACC^7

unsigned int SpiRead(unsigned char add)

{

unsigned char i

unsigned int datal6

add&=0x3f /*6 */

add |=0x80 /* l0*/

SDO=1 /* 1 */

SCK=0

SCK=1

for(i=0 i<8 i++)/* */

{

if(add&0x80==1)

SDO=1

else

SDO=0

SCK=0 /* */

SCK=1

add<<= 1

}

SCK=1 /* 1 */

SCK=0

datal6<<= 1;/* 16 */

for(i=0 i<16 i++)

{

SCK= 1

_nop_()

if(SDI==1)

datal6|=0x01

SCK =0

datal6< < =1

}

return datal6

}

SCK ( ) ( ) ) P1 2(SCK)