Applications Information (Continued)

SAMPLE PROGRAM FOR ADC0841 — INS8039 INTERFACE

CONVERTING TWO RATIOMETRIC, DIFFERENTIAL SIGNALS

ORG 0H

0000 04 10 JMP BEGIN ;START PROGRAM AT ADDR 10

ORG 10H ;MAIN PROGRAM

0010 B9 FF BEGIN: MOV R1,

0FFH ;LOAD R1 WITH A UNUSED ADDR

;LOCATION

0012 B8 20 MOV R0,

20H ;A/D DATA ADDRESS

0014 89 FF ORL P1,

0FFH ;SET PORT 1 OUTPUTS HIGH

0016 23 00 MOV A,00H ;LOAD THE ACC WITH 00

0018 14 50 CALL CONV ;CALL THE CONVERSION SUBROUTINE

;CONTINUE MAIN PROGRAM

Continuous Conversion

DS008557-19

Operating with Automotive Ratiometric Transducers

DS008557-17

(−)

0.15 V

of V

≤V

XDR

≤85

of V

www.national.com 10

Applications Information (Continued)

;CONVERSION SUBROUTINE

;ENTRY: ACC — A/D MUX DATA

;EXIT: ACC — CONVERTED DATA

ORG 50H

0050 99 FE CONV: ANL P1,

0FEH ;CHIP SELECT THE A/D

0052 91 MOVX

R1,A ;START CONVERSION

0053 09 LOOP: IN A,P1 ;INPUT INTR STATE

0054 32 53 JB1 LOOP ;IF INTR

1 GOTO LOOP

0056 81 MOVX A,

R1 ;IF INTR

0 INPUT A/D DATA

0057 89 01 ORL P1,&01H ;CLEAR THE A/D CHIP SELECT

0059 A0 MOV

R0,A ;STORE THE A/D DATA

005A 83 RET ;RETURN TO MAIN PROGRAM

ADC0841_INS8039 Interface

DS008557-20

www.national.com11

Applications Information (Continued)

SAMPLE PROGRAM FOR ADC0841 — NSC800 INTERFACE

0010 NCONV EQU 16 ;TWICE THE NUMBER OF REQUIRED

;CONVERSIONS

000F DEL EQU 15 ;DELAY 60 µsec CONVERSION

001F CS EQU 1FH ;THE BOARD ADDRESS

3C00 ADDTA EQU 003CH ;START OF RAM FOR A/D

;DATA

0000' 00 DTA: DB 08H ;DATA

0001' 0E 1F START: LD C,CS

0003' 06 16 LD B,NCONV

0005' 21 0000' LD HL,DTA

0008' 11 003C LD DE,ADDTA

000B' ED A3 STCONV: OUTI ;START A CONVERSION

000D' EB EX DE,HL ;HL

RAM ADDRESS FOR THE

;A/D DATA

000E' 3E 0F LD A,DEL

0010' 3D WAIT: DEC A ;WAIT 60 µsec FOR THE

0011' C2 0013' JP NZ,WAIT ;CONVERSION TO FINISH

0014' ED A2 INI ;STORE THE A/D’S DATA

;THE REQUIRED CONVERSIONS

COMPLETED?

0016' EB EX DE,HL

0017' C2 000E' JP NZ,STCONV ;IF NOT GOTO STCONV

END

Note 12: A conversion is started, then a 60 µs wait for the A/D to complete a conversion and the data is stored at address ADDTA for the first conversion,

ADDTA + 1 for the second conversion, etc. for a total of 8 conversions.

I/O Interface to NSC800

™

DS008557-21

Part #	ADC0841CCN
Description	IC, A/D CONERTER, 8-BITCMOS, 20PIN DIP
Category	IC
Availability	In Stock
Qty	4

Qty	Price
1 - 2	$10.71477
3 +	$8.11725

ADC0841CCN

Related Items

Technical Document