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In this section we offer some articles, how to program some specific parts of a game or the TI92!
We will add articles, so revisit this section!
How to use the timer in own programs
To use the timer, you first have to set a defined frequency (You don't know the current frequency). I suggest - you have - to set the frequency to $d1 - 30 Hz (30 ticks per second), use port $600016. Now you can use the AutoInt 5 with a counter. There you should use an internal counter, and when this counter is 30, then a second is over. It sounds difficult, but look at the code, it is easy...
;********* VARIABLES
oldTimer dc.l 0
Time dc.w 0 ; Your time!
InternCounter dc.w 0 ; Internal counter
; InstallTimer
; Installs your timer interrupt and sets the right frequency.
InstallTimer:
move.l $64+(5-1)*4,oldTimer
clr.w InternCounter
move.l #TimerInterrupt,$64+(5-1)*4 ; Timer installed!
move.w #$d1,($600016) ; Set frequency
rts
; DeinstallTimer
; Removes your timer interrupt, you should call this routine at the end!
DeinstallTimer:
move.l oldTimer,$64+(5-1)*4
rts
TimerInterrupt:
add.w #1,InternCounter
cmp.w #29,InternCounter ; Since we start with 0
beq ResetInternCounter
rte
ResetInternCounter:
; +1 or -1 of the time
sub.w #1,Time
;add.w #1,Time
clr.w InternCounter
rte
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So, this was, how you can use the timer.
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