Cirrus Logic AN130 - Manual (Page 12)

AN130
12 AN130REV2
;* Routine - write_register
;* Input - COMMAND, HIGHBYTE, MIDBYTE, LOWBYTE
;* Output - none
;* This subroutine writes to the internal registers of the CS55/2122/23/24/28
;*****************************************************************************
write_register BCF PORTA, CS ; Enable ADC
MOVF COMMAND, 0; Load W with Command byte
CALL send_byte ; Send command info
MOVF HIGHBYTE, 0 ; Load W with high byte
CALL send_byte ; Send high byte first..
MOVF MIDBYTE, 0 ; Load W with middle byte
CALL send_byte ; Then the middle byte..
MOVF LOWBYTE, 0 ; Load W with low byte
CALL send_byte ; .. and then the low byte last.
BSF PORTA, CS ; Disable ADC
RETURN ; Exit Subroutine
;*****************************************************************************
;* Routine - read_register
;* Input - COMMAND
;* Output - HIGHBYTE, MIDBYTE, LOWBYTE
;* This subroutine reads from the internal registers of the CS5521/22/23/24/28
;*****************************************************************************
read_register BCF PORTA, CS ; Enable ADC
MOVF COMMAND, 0; Load W with Command Byte
CALL send_byte ; Send Command info
CALL receive_byte ; receive High byte first..
MOVWF HIGHBYTE ; Move W to HIGHBYTE
CALL receive_byte ; and then the middle byte..
MOVWF MIDBYTE ; Move W to MIDBYTE
CALL receive_byte ; and finally the Low byte.
MOVWF LOWBYTE ; Move W to LOWBYTE
BSF PORTA, CS ; Disable ADC
RETURN ; Exit Subroutine
;*****************************************************************************