Level 2 IRQ infinite loop

LeCaravage · 09 July 2022, 18:51

Hi again,

Amiga 500 OCS (512/512).
I have a pb with an infinite loop IRQ.
This is a Lvl 2 irq ($68.W) triggered by Copper at the end of the frame ($009C,$8800).

But right after the RTE, the PC jumps again in ($68.W) and again and again.
Before RTE I do a move.w #$0008,$dff09C. So why cpu acts like the Irq was never accomplished ?

Anyone already had this pb ?

a/b · 09 July 2022, 19:12

Masks $8800 ($0800 specifically) and $0008 don't match. Also, whay are you using lvl2 interrupt for that (some of the CIA timers are at lvl2, as well as keyboard)?
I prefer to use lvl1 ($64.w vector, mask $0004) so it doesn't interfere with other hardware I might need to use (e.g. blitter int, keyboard, CIA timer for music player or trackdisk, ...), and since it's lower priority I don't have to worry how long is the interrupt handler.

LeCaravage · 09 July 2022, 19:45

Switched to lvl1 irq. Works fine. Thank you dear Mr a/b.

09 July 2022, 18:51	#1
LeCaravage Registered User Join Date: May 2017 Location: AmigaLand Posts: 459	Level 2 IRQ infinite loop Hi again, Amiga 500 OCS (512/512). I have a pb with an infinite loop IRQ. This is a Lvl 2 irq ($68.W) triggered by Copper at the end of the frame ($009C,$8800). But right after the RTE, the PC jumps again in ($68.W) and again and again. Before RTE I do a move.w #$0008,$dff09C. So why cpu acts like the Irq was never accomplished ? Anyone already had this pb ?

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09 July 2022, 19:12	#2
a/b Registered User Join Date: Jun 2016 Location: europe Posts: 1,062	Masks $8800 ($0800 specifically) and $0008 don't match. Also, whay are you using lvl2 interrupt for that (some of the CIA timers are at lvl2, as well as keyboard)? I prefer to use lvl1 ($64.w vector, mask $0004) so it doesn't interfere with other hardware I might need to use (e.g. blitter int, keyboard, CIA timer for music player or trackdisk, ...), and since it's lower priority I don't have to worry how long is the interrupt handler.

09 July 2022, 19:45	#3
LeCaravage Registered User Join Date: May 2017 Location: AmigaLand Posts: 459	Switched to lvl1 irq. Works fine. Thank you dear Mr a/b.

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