6502.org

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__STACKSIZE__:  value = $0200, weak = yes;

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__STACKSIZE__:  value = $0200, type = weak

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    __STACKSIZE__: type = weak, value = $0800; # 2k stack

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; ---------------------------------------------------------------------------
; delay.s
; ---------------------------------------------------------------------------
;
; Delay subroutines

.export _delay_3us,_delay_ms

.segment  "CODE"

; ---------------------------------------------------------------------------
; Delay 3us
_delay_3us:
	tax
delay_3us_loop:
	dex
	bne delay_3us_loop
	rts

; ---------------------------------------------------------------------------
; Delay ms
_delay_ms:
	tay
delay_ms_loop1:	
	ldx #$FF
delay_ms_loop2:
	jsr _delay_3us
	dex
	bne delay_ms_loop2
	dey
	bne delay_ms_loop1
	rts

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#ifndef _DELAY_H_
#define _DELAY_H_

extern void __fastcall__ delay_3us (uint8_t duration);
extern void __fastcall__ delay_ms (uint8_t duration);

#endif

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; ---------------------------------------------------------------------------
; hd44780.s
; ---------------------------------------------------------------------------
;
; LCD driver

hd44780_cmd		=	$A380
hd44780_data	=	$A381

.import _delay_3us,_delay_ms
.export _hd44780_init,_hd44780_putc, _hd44780_puts, _hd44780_cmd

.segment "ZEROPAGE"

ptr:
	.res 2

.segment  "CODE"

; ---------------------------------------------------------------------------
; Initialize display
_hd44780_init:
	;delay 100ms
	lda #$64
	jsr _delay_ms
	lda #$30
	sta hd44780_cmd
	;delay 10ms
	lda #$0A
	jsr _delay_ms
	lda #$30
	sta hd44780_cmd
	;delay 100us
	lda #$21
	jsr _delay_3us
	lda #$30
	sta hd44780_cmd
	;delay 100us
	lda #$21
	jsr _delay_3us
	lda #$38
	jsr _hd44780_cmd
	lda #$08
	jsr _hd44780_cmd
	lda #$01
	jsr _hd44780_cmd
	lda #$06
	jsr _hd44780_cmd
	lda #$0C
	jsr _hd44780_cmd
	rts

; ---------------------------------------------------------------------------
; Send one character
_hd44780_putc:
	pha
	jsr _hd44780_busy
	pla
	sta hd44780_data
	rts

; ---------------------------------------------------------------------------
; Send string of characters terminated by \0	
_hd44780_puts:
	ldy #$00
	stx ptr
	sta ptr+1
hd44780_puts_loop:
	lda (ptr),y
	beq hd44780_puts_return
	jsr _hd44780_putc
	iny
	jmp hd44780_puts_loop
hd44780_puts_return:	
	rts

; ---------------------------------------------------------------------------
; Send command
_hd44780_cmd:
	pha
	jsr _hd44780_busy
	pla
	sta hd44780_cmd
	rts
	
; ---------------------------------------------------------------------------
; Wait for busy flag	
_hd44780_busy:
	lda hd44780_cmd
	and #$80
	bne _hd44780_busy
	rts

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#ifndef _HD44780_H_
#define _HD44780_H_

#include <stdint.h>

extern void hd44780_init (void);
extern void __fastcall__ hd44780_putc (char c);
extern void __fastcall__ hd44780_puts (char *str);
extern void __fastcall__ hd44780_cmd (uint8_t cmd);
extern void __fastcall__ hd44780_gotoxy (uint8_t x, uint8_t y);

#endif

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# Adjust the run address to match the .org in the source code
all: main.hex

main.hex: a.out
	bin2hex.py --offset=0xc000 a.out main.hex

a.out: interrupt.o vectors.o main.o hd44780.o delay.o
	ld65 -C ./lib/ethergeiger.cfg -m main.map interrupt.o vectors.o hd44780.o delay.o main.o ./lib/ethergeiger.lib	

main.s: main.c
	cc65 -t none -O --cpu 6502 main.c
	
main.o: main.s
	ca65 --cpu 6502 main.s
	
delay.o: delay.s
	ca65 --cpu 6502 delay.s
	
hd44780.o: hd44780.s
	ca65 --cpu 6502 hd44780.s
	
interrupt.o: interrupt.s
	ca65 --cpu 6502 interrupt.s
	
vectors.o: vectors.s
	ca65 --cpu 6502 vectors.s	
	
clean:
	$(RM) *.o *.lst *.map, *.out, *.hex a.out main.s

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; ---------------------------------------------------------------------------
; Delay 3us
_delay_3us:
   tax
delay_3us_loop:
   dex
   bne delay_3us_loop
   rts

; ---------------------------------------------------------------------------
; Delay ms
_delay_ms:
   tay
delay_ms_loop1:   
   ldx #$FF
delay_ms_loop2:
   jsr _delay_3us
   dex
   bne delay_ms_loop2
   dey
   bne delay_ms_loop1
   rts

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; Delay subroutines

.export _delay_5us,_delay_ms

.segment  "CODE"

; ---------------------------------------------------------------------------
; Delay 5us
; there's an additional 15us overhead for each call, so the
; minimum delay is 20us with increments of 5us. The formula is:
; duration = 5*a + 15, where "a" is the value in the accumulator
; note a value of zero in "a" is treated as 256, not zero!
_delay_5us:
   nop
   tax
delay_5us_loop:
   dex
   bne delay_5us_loop
   rts

; ---------------------------------------------------------------------------
; Delay ms
_delay_ms:
   tay
   lda #196                            ; 196*5 + 15 = 995 (dey&bne take 5 cycles)
delay_ms_loop1:   
   jsr _delay_5us
   dey
   bne delay_ms_loop1
   rts