SRAM TV Image Generation by John Haskins

This is an api / codebase that will generate an image on the tv screen based on the bits of sram. It usues virtually all of the avaialable sram, leaving only 39 bytes for the stack. This yeilds a field 96x82 that looks pretty good sitting on the screen.

Comments, Questions, and Suggestions welcome.

2006.05.13: Finally got everything up on sourceforge, take a look at https://sourceforge.net/projects/avrtv/ for the project details and latest version.

2005.02.09: New version 0.5 includes some upgrades, changed the pixel numbering so that 0,0 is _top_ left instead of bottom. Now included 2 example application, one similar to previouse and a drawing program that uses 6 of the 8 pins on port d. Major enhancments still left to do but may have to wait a while for them.

2005.02.06: New version 0.4 includes basic bitmap support, and a character set stored in EEPROM. Example app writes the character set to the screen. It also includes a Readme talking about the hardware settup, sorry about that for you that downloaded already and don't know how to connect it to the tv.

; /---------------------------------\
; | Draw on a TV, NTSC timing |
; | |
; | Runs at 8MHz on the ATMega16 |
; | |
; |---------------------------------|
; | John Haskins |
; \---------------------------------/

.INCLUDE "m16def.inc"

.include "8MHzM16TVMacs.inc" ; the MARCROs that help the application draw stuff to the tv, should be included at the top of the file

.DEF py=r16
.DEF px=r17
.DEF dir=r18
.DEF btn=r19
.DEF temp1=r20

.EQU BOUND_T=1
.EQU BOUND_B=70
.EQU BOUND_L=1
.EQU BOUND_R=95

.EQU ML=0
.EQU MR=1
.EQU MU=3
.EQU MD=4
.EQU PEN=6
.EQU ERS=7

.EQU BUTTONS=PIND

;-------------------------------------------------------------
.CSEG ; code segment
.ORG $0000 ; begining of code
rjmp reset ; reset interrupt (and start)
.ORG OVF0addr ; location of Timer0 Overflow ISR
rjmp ISR_TOV0 ; 2 Interrupt Service Routine for Timer0 Overflow
.ORG OC0addr ; location of Timer0 Compare Match ISR (shouldn't need to do this but it is what works so...)
rjmp ISR_COMP0 ; 2 Interrupt Service Routine for Timer0 Overflow

;-------------------------------------------------------------

.ORG $0030 ; after last interrupt

reset:
SetupStack ; 4 Setup the Stack ! Required or do yourself
SetupXPointer ; 2 Setup X Pointer ! Required or do yourself
SetupYPointer ; 2 Setup X Pointer ! Required or do yourself
SetupTVState ; 3 Setup TV State Mchn ! Required
SetupTimer0 ; 8 Setup Timer ! Required

;-------------------------------------------------------------

main:
ldi temp1,$ff ; 1
out DDRB,temp1 ; 1
ldi temp1,$00 ; 1
out DDRD,temp1 ; 1

; setup the picture
FillImage $00 ; clear the image

nop
nop

;-----

ClearTimer0 ; ready to begin
sei ; 1 enable interrupts ! Required

init:
ldi px,0
ldi py,71
ldi temp1,96
line:
SPX px,py
inc px
dec temp1
brne line

ldi py,10
ldi px,10
ldi dir,$00
ldi btn,$ff
nop

LDBMI cp1,0,73
LDBMI cp2,1,73
LDBMI cp3,2,73
LDBMI ct,3,73
LDBMI cv,4,73
LDBMI cd,5,73
LDBMI lr,6,73
LDBMI la,7,73
LDBMI lw,8,73

nop
nop

mainLoop:
; rjmp mainLoop; don't do anything

; rcall WasteThousand
; rcall WasteThousand
; rcall WasteThousand
; rcall WasteThousand
; rcall WasteThousand
; rcall WasteThousand
; rcall WasteThousand
; rcall WasteThousand
; rcall WasteThousand
; rcall WasteThousand

nop
nop
TPX px,py
rcall LoadDir
sbrc dir,PEN
rcall PENPixelPre
sbrc dir,ERS
rcall ERSPixelPre
moveX:
sbrc dir,ML
rjmp moveLeft
sbrc dir,MR
rjmp moveRight
moveY:
sbrc dir,MU
rjmp moveUp
sbrc dir,MD
rjmp moveDown
moveDone:
sbrc dir,PEN
rcall PENPixelPost
sbrc dir,ERS
rcall ERSPixelPost

rjmp mainLoop ; 2 keep it going

;-------------------------------------------------------------

MoveRight:
LDBMI ar,10,73
inc px
cpi px,BOUND_R
brlo mrd
dec px
cbr dir,MR
LDBMI arx,10,73
mrd:
rjmp moveY

;-------------------------------------------------------------

MoveLeft:
LDBMI al,10,73
dec px
cpi px,BOUND_L
brsh mld
inc px
cbr dir,ML
LDBMI alx,10,73
mld:
rjmp moveY

;-------------------------------------------------------------

MoveDown:
LDBMI ad,10,73
inc py
cpi py,BOUND_B
brlo mud
dec py
cbr dir,MU
LDBMI adx,10,73
mud:
rjmp moveDone

;-------------------------------------------------------------

MoveUp:
LDBMI au,10,73
dec py
cpi py,BOUND_T
brsh mdd
inc py
cbr dir,MD
LDBMI aux,10,73
mdd:
rjmp moveDone

;-------------------------------------------------------------

LoadDir:
in temp1,BUTTONS
neg temp1
eor btn,temp1
;mov btn,temp1

bst dir,PEN
brts wasPEN
wasERS:
bst btn,PEN
brts donePen

sbr btn,1<<ERS
cbr btn,1<<PEN
rjmp donePEN
wasPEN:
bst btn,ERS
brts donePEN

sbr btn,1<<PEN
cbr btn,1<<ERS
rjmp donePEN
donePEN:
mov dir,btn
in btn,BUTTONS
neg btn
ret

;-------------------------------------------------------------

PENPixelPre:
LDBMI PENICON,11,73
;LDBMI sp,11,73
SPX px,py
ret

;-------------------------------------------------------------

ERSPixelPre:
LDBMI ERSICON,11,73
;LDBMI sp,11,73
CPX px,py
ret

;-------------------------------------------------------------

PENPixelPost:
; SPX px,py
ret

;-------------------------------------------------------------

ERSPixelPost:
; CPX px,py
ret

;-------------------------------------------------------------


; Include the TV outpu routines
.include "8MHzM16TV.inc" ; The main API, has the interrupt routines and draws to the tv
.include "Delay.inc" ; Delay routines
.include "TVDrawChars.inc" ; EEPROM character data
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Another Link: http://www.avrfreaks.net/index.php?module=...ect&item_id=287
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