[Coco] 6809 FPGA

[Dave Philipsen]

On 9/10/2015 10:12 PM, Bill Nobel wrote:
> Hey all,  I (as some of you know) have been trying to get Grant Searles project running on a DE0 Nano.  I have made some good advancements (Many, many thanks greatly to Roger Taylor and Dave Philipsen).
>
> But I need a little help again.  I took Rogers suggestion of updating my Quartus ii software to 15.0 and things did dramatically change.  I now have a flashing cursor in the top left corner (which should be there upon init of the VGA circuit).  I do have what seems like a little sync noise on the background (nothing serious).  I could post a pic, but I don’t want to clog the list.  This is all I get once I program the DE0 with Grants code.
>
> I think there is a problem with my selection of the external RAM chip (and or the pins I chose to drive it, it is all on GPIO-0)  I am using a Hitachi 628128 128k SRAM (only using 64k).  I am personally thinking, looking at the data sheet for the RAM, that it might not handle 3.3v CMOS levels good enough.  Am I correct?

Yep, that's a 5v SRAM.  And my guess is you need a 3.3v SRAM.  I am not 
positive on what the DE0 does for I/O but if it's like the DE1 then it's 
3.3v.


>
> Also, I do think something is wrong in the ROM code, it does compile, but I see in the reports, that there is a rollover in the intel HEX code and I don’t see any LU’s allocated for it in the compile reports.  I get a total of 44 warnings (most are for pin assignments I have not assigned yet).

Not sure what you mean by rollover.

>
> I also see a discrepancy on the pin planner versus the assignment editor, The pins are duplicated in the assignment editor, one set stating my location assignments, the other just stating location.  Is this normal?

You could have some pins duplicated in the assignment editor if one line 
assigns the signal to a pin and another line defines something else 
about the pin like whether it has a weak pull-up resistor attached to it 
for example.

> Bill Nobel
>
>

Dave Philipsen


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