RGB to HDMI using a Pi Zero and a small CPLD

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danielj
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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by danielj » Wed Nov 27, 2019 7:17 pm

=D>

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-B-
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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by -B- » Fri Nov 29, 2019 11:47 am

Have you tried the QL yet, with its famous overscan in monitor mode?
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IanB
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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by IanB » Fri Nov 29, 2019 6:36 pm

-B- wrote:
Fri Nov 29, 2019 11:47 am
Have you tried the QL yet, with its famous overscan in monitor mode?
Unfortunately I don't have a QL but it looks like it has a standard RGB TTL output so it should work, it's just a matter of creating a profile.
Does anyone here have a QL?

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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by -B- » Fri Nov 29, 2019 7:10 pm

I have a couple but I’m not in the UK.
I will be for Christmas though, so if you’d like me to lend you one....

Neil.
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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by IanB » Fri Nov 29, 2019 11:12 pm

-B- wrote:
Fri Nov 29, 2019 7:10 pm
I have a couple but I’m not in the UK.
I will be for Christmas though, so if you’d like me to lend you one....
That might be useful. I can probably create a profile with just some tech info although it would have to be connected to a real machine for the final tweaks.

Do you know what pixel clock frequency the QL uses? (It seems to be 10Mhz from online info)
Also how many clock cycles are there in a video line? (This should be around 640 but may vary 1 or 2 either way)

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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by -B- » Fri Nov 29, 2019 11:35 pm

IanB wrote:
Fri Nov 29, 2019 11:12 pm
Do you know what pixel clock frequency the QL uses? (It seems to be 10Mhz from online info)
Also how many clock cycles are there in a video line? (This should be around 640 but may vary 1 or 2 either way)
This might help...
ZX8301.pdf
(376.68 KiB) Downloaded 19 times

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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by IanB » Sat Nov 30, 2019 12:26 am

-B- wrote:
Fri Nov 29, 2019 11:35 pm
This might help...
ZX8301.pdf
Thanks, it was 10Mhz & 640 clock cycles so I created a new profile based on that, you can try it when the new software is released.

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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by IanB » Sat Dec 14, 2019 2:16 pm

Got my new issue 2 combined RGB and YUV boards back from JLC so I can now use it for analog RGB sources, 6847 YUV type sources and monochrome sources.

Here it is working with the Amstrad CPC:
rgb.jpg

And an Atom:
yuv.jpg

It even works with the beeb / electron:
beeb.jpg
(It isn't require of course as they will work on the raw TTL inputs but it does mean you can swap between supported machines without having to remove the analog interface)

Here's a closeup of the new board:
Closeup.jpg
(It's connected via a test harness so I can do signal measurements)

There are still a few issues to sort out as the software really doesn't like noise in the sync input and that can happen when setting up the sync levels but once the profiles is setup it seems to work very smoothly.

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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by -B- » Sat Dec 14, 2019 2:34 pm

Excellent stuff!
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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by IanB » Sat Dec 28, 2019 3:36 pm

I've added support for a few more machines:

Camputers Lynx:
capture6.png
This one has a 3 bit TTL output like the beeb.

Colour Genie:
capture4.png
This one uses TTL connections picked up internally.

Tandy Micro Color Computer: (MC-10)
capture2.png
This one uses the new RGB/YUV interface with YUV signals picked up internally and that should also work with the Tandy color computers 1 & 2.
Interestingly this has quite different settings to the Dragon 32 as the PAL Tandy color computers use a slightly different clock frequency for the 6847.

The Dragon 32 also works with the RGB/YUV interface (previously mentioned in the Aom thread).
As it has a composite output I was able to do a side by side comparison with the RGBtoHD output: (composite on the left, RGBtoHD on the right)
sidebyside.jpg
Composite doesn't actually look that bad in the photo but here are a couple of closeups:

This is composite using a Retrotink 2X converter:
retrotink.jpg

This is RGBtoHD using the RGB/YUV addon interface:
rgb2hd.jpg

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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by aotta » Mon Jan 20, 2020 2:15 pm

excellent!
but when the new ttl version will be published? on github rgbtohdmi i found nothing about...

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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by hoglet » Mon Jan 20, 2020 2:18 pm

aotta wrote:
Mon Jan 20, 2020 2:15 pm
excellent!
but when the new ttl version will be published? on github rgbtohdmi i found nothing about...
All the work in the last 12 months has been happening in the dev branch:
https://github.com/hoglet67/RGBtoHDMI/tree/dev

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Re: RGB to HDMI using a Pi Zero and a small CPLD

Post by aotta » Mon Jan 20, 2020 2:44 pm

thank you hoglet, i missed the dev branch! i'll order a pcb asap!

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