mirror of
https://github.com/EranMorkon/AMTS.git
synced 2023-12-28 16:48:38 +00:00
91 lines
4.5 KiB
ArmAsm
91 lines
4.5 KiB
ArmAsm
;******************************************************************************
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;* Z80 Assemblerprogramm *
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;* Josef Reisinger *
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;* josef.reisinger@htl-hl.ac.at *
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;* 26/04/2015 *
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;******************************************************************************
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; ---------------------------- PIO 82C55 I/O ---------------------------------
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PIO_A: EQU $80 ; (INPUT)
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PIO_B: EQU $81 ; (OUTPUT) OUT TO LEDS
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PIO_C: EQU $82 ; (INPUT) IN from DIP SWITCHES
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PIO_CON: EQU $83 ; CONTROL BYTE PIO 82C55
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; --------------------------- CTC Z80 Timer Counter --------------------------
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CTC0 EQU $00 ; Channel 0
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CTC1 EQU $01 ; Channel 1
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CTC2 EQU $02 ; Channel 2
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CTC3 EQU $03 ; Channel 3
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; -------------------------- SIO (USART) ----------------------------------------
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SIO_A_D: EQU $40 ; Channel A Data Register
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SIO_B_D: EQU $41 ; Channel B Data Register
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SIO_A_C: EQU $42 ; Channel A Control Register
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SIO_B_C: EQU $43 ; Channel B Control Register
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;-------------------------- CONSTANTS ----------------------------------------
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RAMTOP: EQU $FFFF ; 32Kb RAM 8000H-FFFFH
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COUNTER: EQU $8000 ; RAM Counter
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;******************************************************************************
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;* RESET HANDLER *
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;* Function: Initalize system and start Main Programm *
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;******************************************************************************
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ORG $0000
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DI ; Disable interrupt
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LD SP,RAMTOP ; Set stack pointer
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JP MAIN ; jump to Main program
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;*******************************************************************
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;* MAIN PROGRAM *
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;*******************************************************************
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ORG $0100
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MAIN: LD HL,COUNTER ; Reset RAM Counter
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LD A,$00
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LD (HL),A
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; ------------------ Initialize PIO ----------------
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LD A,$99 ; Initialize 8255: PA0-PA7=IN (DIP SWITCHES), PB0-PB7=OUT (LEDS),
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OUT (PIO_CON),A ; PC0-PC7=IN, Mode 0 Selektion
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;------------------ Configure CTC -----------------------
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LD A,$A5 ; Configure CTC Channel 0:Interrupt, Timer Mode, Prescaler = 256,
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OUT (CTC0),A ; trigger on positive edge, next word = time constant, Channel continuous result operation
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LD A,$FF ; Write Time constant 255*256*552ns= 36,03ms
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OUT (CTC0),A
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LD A,$A8 ; Loading Interrupt Vector register
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OUT (CTC0),A ; trigger on positive edge, next word = time constant, Channel continuous result operation
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;---------------------- Configure Interrupt -----------------
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LD A,$01 ; Loading Interrupt Register
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LD I,A
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IM 2 ; Interrupt Mode 2
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EI ; Enable Interrupt
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;--------------------- Main Program --------------------------
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AGAIN: JP AGAIN ; Endlos
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;******************************************************************************
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;* INTERRUPT SERVICE ROUTINE *
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;* CTC Channel 0 *
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;******************************************************************************
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ORG $01A8
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DEFW _INT_CTC
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_INT_CTC: PUSH AF
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PUSH HL
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LD HL,COUNTER
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LD A,(HL) ; Read Counter
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INC A ; Increment Counter
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CP $07 ; 252,21ms reached?
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JP NZ,_END_INT
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LD A,$00 ; Reset Counter
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IN A,(PIO_B) ; Toggle LED's with 2Hz
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CPL
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OUT (PIO_B),A ;
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_END_INT: LD (HL),A ; Store Counter
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POP HL
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POP AF
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EI ; Entry Point of Interrupt Service Routine
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RETI
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