Rainbow Electronics АDC0805 - Manual (Page 26)

Functional Description
(Continued)
TL H 5671 – 26
Note 1 Numbers in parentheses refer to MC6800 CPU pin out
Note 2 Numbers of letters in brackets refer to standard M6800 system common bus code
FIGURE 16 Interfacing Multiple A Ds in an MC6800 System
SAMPLE PROGRAM FOR FIGURE 16 INTERFACING MULTIPLE A Ds IN AN MC6800 SYSTEM
ADDRESS HEX CODE MNEMONICS COMMENTS
0010 DF 44 DATAIN STX TEMP Save Contents of X
0012 CE 00 2A LDX $002A Upon IRQ LOW CPU
0015 FF FF F8 STX $FFF8 Jumps to 002A
0018 B7 50 00 STAA $5000 Starts all A D’s
001B 0E CLI
001C 3E WAI Wait for interrupt
001D CE 50 00 LDX $5000
0020 DF 40 STX INDEX1 Reset both INDEX
0022 CE 02 00 LDX $0200 1 and 2 to starting
0025 DF 42 STX INDEX2 addresses
0027 DE 44 LDX TEMP
0029 39 RTS Return from subroutine
002A DE 40 INTRPT LDX INDEX1 INDEX1 x X
002C A6 00 LDAA X Read data in from A D at X
002E 08 INX Increment X by one
002F DF 40 STX INDEX1 X x INDEX1
0031 DE 42 LDX INDEX2 INDEX2 x X
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