MiSTer FPGA Forum

Hi,

I wonder if anyone has had a similar issue. I've put together a simple arcade core - I'm going to start publishing the step in videos coming up - anyway I'm putting the controller inputs into my core as so (Verilog):

.BUTTONS(~{m_coin, m_start, m_bomb, m_fire, m_right, m_left, m_down, m_up}),

This is the standard setup for the controls as far as I see.

Now if I pull from those controls in that order it works ok. However in my instantiated module, if I change the order like this:

.D({IN0[7:6],in_coin,in_fire,in_right,in_down,in_left,in_up}),

My core doesn't like it and is creating a permanent interrupt on the CPU. Why on earth would the order matter like this?

Has anyone else come across this issue at all?
Thanks.

Do you have the code posted up anywhere so we can see more details of what is going on?

Yeah, it's a bit tough to reason about without more context. The only scenario I can imagine at the moment that doesn't seem completely off the wall is something along these lines:

• A CPU that vectors interrupts based on the data bus
• The inputs are applied to the data bus during the interrupt vector cycle
• One order of inputs happens to invoke the expected ISR
• The other order happens to invoke a different ISR that doesn't acknowledge the interrupting device

Thanks - I'll setup the code in a github. At the moment I'm just fudging the MiSTer shell to allow the pass-through of the comp sync and RGB signals, so it's only working on my CRT.

The strange thing is that if I change the order of the up and right control inputs it works. I really don't see how that would affect anything.

I can use Signal Tap to monitor the core if I'm using it direct for the USB blaster SOF, but how do I get it working if I'm using the usual RBF with the full MiSTer shell?

nico24 wrote: ↑Thu Nov 25, 2021 5:42 pm I can use Signal Tap to monitor the core if I'm using it direct for the USB blaster SOF, but how do I get it working if I'm using the usual RBF with the full MiSTer shell?

There isn't much of a difference except that you start the rbf/mra on MiSTer instead of clicking the Program Device button. What is the issue that you are having?

I'll give it a go. I didn't now you could have it ready for acquisition if you didn't use the Program Device route!
Thanks.