penguin86/pato-z80-home-computer
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Merge branch 'master' of ichibi:/home/git/Repositories/pato-z80-home-computer

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This commit is contained in:
Daniele Verducci (ZenPenguin) 2021-01-10 07:23:18 +01:00
commit 66414a2e57
1 changed files with 38 additions and 18 deletions
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46
pat80-io-devices/composite-pal-adapter/software/avr-assembly/main.asm
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@ -16,6 +16,17 @@
; Video pin: PA0 (pin 1)
; Sync pin: PC0 (pin 22)
; Debug hsync pin: PC1 (pin 23)
;
; RESERVED REGISTERS:
; R25: Current status (what the interrupt should do when fired):
; 0, 2, 4, 6, 8 = long sync start (sync pin low and register next interrupt after 30uS)
; 1, 3, 5, 7, 9 = long sync end (sync pin high and register next interrupt after 2uS)
; 10, 12, 14, 16, 18 = short sync start (sync pin low and register next interrupt after 2uS)
; 11, 13, 15, 17, 19 = short sync end (sync pin high and register next interrupt after 30uS)
; 20 = draw lines (draw 304 lines complete with line sync and back porch, then start short
; sync: sync pin low and next interrupt after 2uS)
; 21, 23, 25, 27, 29 = short sync start (sync pin low and register next interrupt after 2uS)
; 22, 24, 26, 28, 30 = short sync end (sync pin high, reset R25 to 0 and register next interrupt after 30uS)
.include "atmega1284definition.asm"
@ -29,29 +40,27 @@
; start vector
.org 0x0000
rjmp main ; jump to main label
.org 0x0002
rjmp on_int0 ; interrupt 0
; main program
main:
; setup
sbi DDRC, SYNC_PIN ; set pin as output
sbi DDRC, DEBUG_PIN ; set pin as output
ldi r16, 0xFF
out DDRA, r16 ; set port as output (contains video pin)
;*** Load data into ram ***
; Set X to 0x0100
ldi r27, high(FRAMEBUFFER<<1)
ldi r26, low(FRAMEBUFFER<<1)
; Set Z to 0x1000 (cat image)
ldi r31, high(CAT_IMAGE<<1)
ldi r30, low(CAT_IMAGE<<1)
;*** Load data into ram ***
; Set X to 0x0100
ldi r27, high(FRAMEBUFFER<<1)
ldi r26, low(FRAMEBUFFER<<1)
; Set Z to 0x1000 (cat image)
ldi r31, high(CAT_IMAGE<<1)
ldi r30, low(CAT_IMAGE<<1)
load_mem_loop:
load_mem_loop:
lpm r17, Z+
;ldi r17, 0b00001111
st X+, r17
@ -61,6 +70,17 @@ load_mem_loop:
cpi r26, 0b11000000
brne load_mem_loop ; if not 0, repeat h_picture_loop
; loop forever
forever:
jmp forever
; ********* FUNCTIONS CALLED BY INTERRUPT ***********
on_int0:
; called two times per line (every 32 uS) during hsync. Disabled while drawing picture.
v_refresh_loop:
; set X register to framebuffer start 0x0100