; Gestione di un AD7715 ( A to D Converter, Sigma-delta, 16 Bit ) Analog Device per 68HC908GP32
; Pin Out di interconnessione per GP32 S-DIL 42 e AD7715 16DIL
;	GP32		AD7715
;	36 PA1		4 CS
;	6 Reset		5 Reset
;	32 PB7		12 DRDY
;	18 PD3/SCK	1 SCK
;	16 PD1/MISO	13 DOUT
;	17 PD2/MOSI	14 DIN
; 
; AD7715 non misura segnali in input inferiori a 600 mV se programmato con il buffer attivo
; Si puņ evitare l'inconveniente ponendo a -600 mV il pin 11 AnGND ( 1N4148 in Pull-down diretto verso -Vss rispetto a GND )

$include 'gp32regs.inc'
COMMAND        	EQU   $50        ;COMANDO DA ESEGUIRE
ADCHI          	EQU   $51        ;VALORE BINARIO LETTURA ADC BYTE H
ADCLOW         	EQU   $52        ;VALORE BINARIO LETTURA ADC BYTE L
DELAY          	EQU   $53        ;CONTATORE RITARDO PER SPI SENDATA

* PRESET AD7715
* GAIN= 1   * AUTOCAL * CLK HI *  50Hz * UNIPOLAR * BUFFER= OFF * NO FSYNC

ADCPRESET		LDA     #$FF
ADCPA			STA     $FFFF			;watch dog refresh
                    	BRSET   7,PORTB,ADCPA         	;WAIT UNTIL DRDY = LOW

                    	MOV     #%00010000,COMMAND
                   	JSR     SEND
                    	LDA     SPSCR
                    	LDA     SPDR

                    	LDA     #$FF
ADCPL               	STA     $FFFF
                    	BRSET   7,PORTB,ADCPL         	;WAIT UNTIL DRDY = LOW

                    	MOV     #%01100110,COMMAND      ;SET UP REGISTER
                    	JSR     SEND
                    	LDA     SPSCR
                    	LDA     SPDR

                    	LDA     #$FF
ADCPM               	STA     $FFFF
                    	BRSET   7,PORTB,ADCPM         	;WAIT UNTIL DRDY = LOW

**********************************************************
* SUB INVIO DATO IN SERIALE SINCRONA ( DATO IN COMMAND ) *
**********************************************************

SEND                	BRCLR   3,SPSCR,SEND
                    	MOV     COMMAND,SPDR

                    	MOV     #$FF,DELAY      	;RITARDO
SENDA               	DEC     DELAY
                    	BNE     SENDA
                    	RTS

*************************************************
* SUB LETTURA ADC 16 BIT AD7715                 *
* RESTITUISCE SU ADCHI E ADCLOW IL VALORE LETTO *
*************************************************
READC        		LDA	  $FF
RIB           		STA       $FFFF
              		BRSET     7,PORTB,RIB     	;WAIT UNTIL DRDY = LOW

              		LDA       #%00111000      	;PERFORM READ DATA
              		STA       COMMAND
              		JSR       SEND
RIC           		STA       $FFFF
              		BRSET     7,PORTB,RIC     	;WAIT UNTIL DRDY = LOW
              		LDA       SPSCR
              		LDA       SPDR

              		CLR       COMMAND
              		JSR       SEND
              		LDA       SPSCR
              		LDA       SPDR
              		STA       ADCHI

              		JSR       SEND
              		LDA       SPSCR
              		LDA       SPDR
              		STA       ADCLOW
              		RTS