Cirrus Logic AN118 - Manual (Page 27)

AN118
AN118REV2 27
/**************************************************************/
/* Routine - Delay
*/
/* Input - none */
/* Output - none */
/* Description - This routine is used as a LED delay routine */
/**************************************************************/
void Delay(void) {
data int j;
for (j=0; j<10000; j++)
for (j=0; j<10000; j++);
}
;****************************************************************
;* Routine - RECEIVE_BYTE
;* Input - none
;* Output - Byte received is placed in R7
;* Description - This subroutine receives 1 byte from converter
;****************************************************************
; The function prototype is: char RECEIVE_BYTE(void);
$DEBUG
USING 0
; Use register bank 0
TCOD SEGMENT CODE ; Define ROUT as a segment of code
PUBLIC RECEIVE_BYTE ; Make subroutine global
RSEG TCOD ; Make code relocatable
RECEIVE_BYTE:
MOV R1,#08 ; Set count to 8 to receive byte
LOOP: ; Receive the byte
MOV C,P1.2 ; Move bit to carry
RLC A ; Rotate A in preparation for next bit
SETB P1.3 ; Set SCLK
CLR P1.3 ; Clear SCLK
DJNZ R1,LOOP ; Decrement byte, repeat loop if not zero
MOV R7,A ; Byte to be return is placed in R7
RET ; Exit subroutine
END