Rainbow Electronics АDC0805 - Manual (Page 24)

Functional Description
(Continued)
SAMPLE PROGRAM FOR FIGURE 14 ADC0801-MC6800 CPU INTERFACE
0010 DF 36 DATAIN STX TEMP2 Save contents of X
0012 CE 00 2C LDX $002C Upon IRQ low CPU
0015 FF FF F8 STX $FFF8 jumps to 002C
0018 B7 50 00 STAA $5000 Start ADC0801
001B 0E CLI
001C 3E CONVRT WAI Wait for interrupt
001D DE 34 LDX TEMP1
001F 8C 02 0F CPX $020F Is final data stored
0022 27 14 BEQ ENDP
0024 B7 50 00 STAA $5000 Restarts ADC0801
0027 08 INX
0028 DF 34 STX TEMP1
002A 20 F0 BRA CONVRT
002C DE 34 INTRPT LDX TEMP1
002E B6 50 00 LDAA $5000 Read data
0031 A7 00 STAA X Store it at X
0033 3B RTI
0034 02 00 TEMP1 FDB $0200 Starting address for
data storage
0036 00 00 TEMP2 FDB $0000
0038 CE 02 00 ENDP LDX $0200 Reinitialize TEMP1
003B DF 34 STX TEMP1
003D DE 36 LDX TEMP2
003F 39 RTS Return from subroutine
To user’s program
Note 1 In order for the microprocessor to service subroutines and interrupts the stack pointer must be dimensioned in the user’s program
TL H 5671 – 25
FIGURE 15 ADC0801 – MC6820 PIA Interface
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