I agree.  PRUs are an amazing resource in the beaglebone computers - and -
it is unfortunate there aren't more pins.  I have an idea for a project
along similar lines, to use the PRUs to emulate a bus master for a now
obsolete workstation bus.  It's 32 bits wide and I was thinking of an
approach similar to yours, using 8-bits of data and a bunch of latches.
Good to know someone else has had success with this.

One last question.  How are you sharing the data with the HDMI frame
buffer?

Cheers, Dan

On Thu, Nov 21, 2019 at 9:44 AM Tomas Espeleta <[email protected]>
wrote:

> Thanks Dan!
> Yep, I created two versions: one capturing READS + interpreting the video
> address, and another one capturing the 6502 writes. With the latter was
> much easier to tune the timings, so that's what I'm doing.
>
> I use 8 bits in parallel, hooking the BBB to the Apple II peripherals bus.
> I need 24 bits in total, so I use some electronics (a multiplexer and 3
> buffers), and time everything to capture each byte at the right time
> (ADDRESS LOW, ADDRESS HIGH, DATA).
>
> It's a pity that HDMI on the BBB steel so many pins from the PRU,
> otherwise I could write to the bus, emulate audio on hdmi, etc...
>
> PRU are amazing!
>
> On Thu, Nov 21, 2019 at 5:24 PM Dan Julio <[email protected]> wrote:
>
>> Very neat Tomas!
>>
>> A PRU is capturing the write to the video memory?  Are you reading the
>> data in via a parallel interface or serializing it?
>>
>> Cheers, Dan
>>
>> On Wednesday, November 20, 2019 at 9:19:44 AM UTC-7, Tomas Espeleta wrote:
>>>
>>> Helllo Guys,
>>> I just wanted to share the first steps of my project: take a look to my
>>> facebook post:
>>>
>>> https://www.facebook.com/groups/5251478676/permalink/10159148656378677/
>>>
>>> Best,
>>> Tomas
>>>
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