Open source A500 simple SPI controller

[nikosidis]

Originally Posted by Mathesar

Thanks! That is of great help. Nice black accelerator! It looks pretty crowded and to me it seems the usual "cpu relocator" design will not clear the rgb2hdmi board. I now also know why you don't care about the emc shield so much, it doesn't fit anyway with the rgb2hdmi board

Haha, yes, I'm sure the shield would not fit but I do not like them anyway


I did my own design of the accelerator pcb. Just wanted something original. Glad you like it

[Mathesar]

I have been puzzling a bit with the accelerator but it seems hard to design a relocator style SSPI controller that leaves room for a RGB2HDM board, a rev.5 ROM adapter, shield, etc, etc. It is just too crowded near the CPU and Denise on an A500. That made me thinking about alternative locations for the SSPI controller and I wonder what your thoughts are.

The main attraction of this design is that it is simple, no programmable logic, no hard to get and fancy chips but just some jellybean logic chips. If I would permit myself the use of a microcontroller, I could make the SSPI controller piggyback on of the CIA chips, preferably the even CIA as the odd CIA could be covered by some styles of RGB2HDM adapters and/or CPU relocators. This would be like some sort of "internal SD-BOX". Something like a small PIC together with a level translator chip would be all that is needed. It would be faster too. It would break the "no programmers required" mantra though...

Another idea I had is too piggyback the controller on Gary. There is plenty of space around Gary. However, Gary is missing a few datalines that would have to be taken from somewhere else. So that would mean soldering some wires to the main board. Not ideal but cheap and simple.

The third option is the trapdoor slot. That would mean that the controller lives on the chipram bus that would probably make it a bit slower. It would also mean that a gary adapter is needed to mess with the addressing and a wire soldered to the motherboard to control A19 into Agnus. Personally I do not like this options so much.

A fourth option would be to try to make the SSPI controller less tall by using pinheaders like this: https://nl.aliexpress.com/item/32791...yAdapt=glo2nld It would still be a tight fit though...

What are your thoughts?

[pandy71]

Originally Posted by Mathesar

The main attraction of this design is that it is simple, no programmable logic, no hard to get and fancy chips but just some jellybean logic chips. If I would permit myself the use of a microcontroller, I could make the SSPI controller piggyback on of the CIA chips, preferably the even CIA as the odd CIA could be covered by some styles of RGB2HDM adapters and/or CPU relocators. This would be like some sort of "internal SD-BOX". Something like a small PIC together with a level translator chip would be all that is needed. It would be faster too. It would break the "no programmers required" mantra though...
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What are your thoughts?

If programmable uC can be programmed trough simple programmer (literally DIY or even better accommodate at the same PCB so introduce possibility of ISP by Amiga being able to reprogram / update uC - probably better to introduce some HW protection as jumper or mechanical switch to allow for this) then it is not substantially different than plain TTL logic.

[levo-ace]

Is this board shared anywhere? ( pcbway etc. )
are there any gerber files?

[Mathesar]

It's on Github. I would recommend aisler for PCB manufacturing, you can directly upload the kicad pcb project file there.

[utri007]

What would be cool is CDTV's diagnostic slot version. It has all the same signals as a Zorro slot, but different form. I would still like to see Zorro version of this.