;**************************************************
;    Example 4
;**************************************************

;example on how to use A/D Converter                        
     
;written by Kenrick Chin
;version: 1.00 1997 Aug 22

;**************************************************
;    Hardware Constants
;**************************************************

REGS      EQU  $1000     ;base address of I/O registers
EEPROM	  EQU  $F800

ADCTL     EQU  $30            ;A/D Control Register
ADR1      EQU  $31            ;A/D Result Register 1
ADR2      EQU  $32            ;A/D Result Register 2
ADR3      EQU  $33            ;A/D Result Register 3
ADR4      EQU  $34            ;A/D Result Register 4

OPTION    EQU  $39            ;System Configuration Options

;ADCTL bit masks
CCF       EQU  $80            ;Conversion Complete Flag
SCAN      EQU  $20            ;Continuous Scan mode
MULT      EQU  $10            ;Multiple-Channel mode

;OPTION bit masks
ADPU      EQU  $80            ;A/D Power Up

;**************************************************
;         Start of code
;**************************************************

          ORG  EEPROM

;**************************************************
;         Start of program
;**************************************************
rstrt
          LDX    #REGS        ;set up I/O base address
          BSET   OPTION,X ADPU  ;power up A/D system

main
          LDB    #MULT        ;select Multiple-channel mode
          STB    ADCTL,X      ;start conversion

wait      BRCLR  ADCTL,X CCF wait  ;wait for conversion

          LDB    ADR1,X       ;get A/D register 1
           :
          LDB    ADR2,X       ;get A/D register 2
           :
          LDB    ADR3,X       ;get A/D register 3
           :
          LDB    ADR4,X       ;get A/D register 4
           :
           :
          BRA    main         ;loop forever

;**************************************************
;         Interrupt Vectors
;**************************************************

          ORG    $FFFE
          FDB    rstrt        ;cold reset address

          END