I'm currently implementing a simple timer (Jiffy Clock) for my SBC.
So I try timer 1 in free run mode and want to count interrupts but nothing happens.
I look at the /IRQ pin of the 6522 with my logic analyzer and nothing happens there either.
My initialization currently looks like this:
Code:
sei
lda #%01111111
sta VIA_IER ; disable all interrupts
; setting free run mode with interrupts enabled
lda #%01000000
sta VIA_ACR
lda #%11000000
sta VIA_IER ; enable interrupt for timer 1
; setting the vias timer 1 in free run mode, jiffy timer, load with
lda #<JIFFY_VIA_TIMER_LOAD
sta VIA_T1LL
lda #>JIFFY_VIA_TIMER_LOAD
sta VIA_T1LH
cli
i also tried #%11000000, so that i can see an output on the PB7 pin, PB7 works, but no signal on the IRQ Pin.
When i trigger manually the IRQ Pin the IRQ Service routine worked.
IRQ is wired as wired-OR with an 3k3 Resistor to +5V.
The 6522 is an N Type- so should be ok with wired OR.
PS.: i did not change the IC.
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don't count on me, i'm engineer (Animotion)
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