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Project: HDMI/DVI out for STFM

Posted: Tue Nov 19, 2019 11:28 pm
by Darklord
Hmm, so when you say "FM" does that mean it has to be ST models with a modulator?

I'm thinking about my STacy, of course. :)

Project: HDMI/DVI out for STFM

Posted: Tue Nov 19, 2019 11:37 pm
by Icky
Darklord wrote:
Tue Nov 19, 2019 11:28 pm
Hmm, so when you say "FM" does that mean it has to be ST models with a modulator?

I'm thinking about my STacy, of course. :)
This works with STF as well as STFM.

Project: HDMI/DVI out for STFM

Posted: Wed Nov 20, 2019 12:20 am
by Smonson
It might be a bit power-hungry for the Stacy, it draws about 250-300mA. At the end of the day though, you just need a standard ST shifter.

Project: HDMI/DVI out for STFM

Posted: Sat Nov 30, 2019 9:01 am
by Smonson
There's something seriously wrong with the new v6 board, and I can't figure out what the problem is. The MAX3814 HDMI interface IC gets really hot, really fast - and the whole thing uses an extra 150mA or so over the previous one. So I've redone the artwork so that the MAX3814 is connected more like how it was in v5 with a ground plane under it and no vias in the signal paths or near the HDMI connector, plus I've added back-termination resistors and another bypass cap (I had 2, the datasheet recommends 3). I also moved all the bypass capacitors to the back of the board - first time I've ever done that. I hope that cleaning up noise and power/ground stuff might help - after all, this thing is running at 320MHz.

So, sorry about the lack of good news, but it's going to need another spin through the process.

Project: HDMI/DVI out for STFM

Posted: Sat Nov 30, 2019 10:42 am
by exxos
Oh no :( Anything I can do to help ?

But yeah, if you only change the PCB layout, then at high speeds its enough. I've had 2 volts oscillations between GND pins on the CPU and thats like 1cm long track! Normally there's a recommended PCB layout for the chips in the datasheets. I always use a GND & VCC plane now. Slap some ceramics as close to the devices power pins as possible. Any slight angles in tracks will aggravate oscillations. Via's are not a good idea for high speed stuff. Its one reason I spent so long trying to keep via's to a minimum on the H4 board, or if they have to be used, on shorter length traces only / lower speed signals.

Project: HDMI/DVI out for STFM

Posted: Sat Nov 30, 2019 10:56 am
by Smonson
The PCB layout is really all I changed in this revision of the board, although I also moved some of the FPGA pins around for routing reasons. I removed the ground plane for a stupid reason - I was reading a recommended layout plan for the HDMI connector and it proposed removing the ground plane from under the connector. I extrapolated that to the MAX3814. I thought it might have something to do with capacitance between the tracks and a nearby ground at higher speeds (HDMI can go up to 12GHz). But it turns out the MAX3814 datasheet recommends a ground plane, so that's gone back in for 6.1.

I didn't include the back-termination resistors in the original design because when this IC wasn't present at all (with the FPGA driving the HDMI), there weren't any. So I stuck to what was working, and indeed, it seemed to be working fine until now!

There's no recommended layout in the datasheet (and no application note!) - but tonight I read the datasheet for the dev board, and it's got a layout almost exactly the same as what I've set up for the next version. The only differences are that they put the bypass caps on the top, and they used curved tracks instead of 45-degree bevels. I guess gently curved tracks might have a positive effect at 1.6GHz (MAX3814's top speed)? :shrug:

I carefully checked the IO bank voltages etc in Quartus but couldn't find anything suss in the FPGA side.

Project: HDMI/DVI out for STFM

Posted: Sat Nov 30, 2019 1:51 pm
by exxos
There's a eval kit for it which has some layouts in it. Round short traces are better for higher frequencies and every mm of track can be critical.

Project: HDMI/DVI out for STFM

Posted: Wed Mar 18, 2020 1:18 pm
by Icky
Great work by @Smonson on TOS select of all three resolution options and coupled with the HDMI / Shifter board to allow a user to use an HDMI cable and switch between all three resolutions with out removing a cable.

TOS changes - viewtopic.php?f=50&t=2563

Video of all three resolution changes. (Screen wobble is due to issue with my boards)

Re: Project: HDMI/DVI out for STFM

Posted: Sat Apr 18, 2020 11:31 pm
by Icky
@exxos and I have been working with @Smonson to help with the HDMI development on the STFM. We have been doing a lot of work behind the scenes but the lockdown has put a delay on some of the progress so we thought we would share where we are now to give you all a sneak preview.

We have come up with a small board (and will most likely shrink further) for the H4 that will provide HDMI out through the monitor port of the case. This is one of the holy grails for an ST setup. The H4 board which is a modern remake of the STFM with lots of fixes and a plug in module to provide HDMI out with rock solid video to use on modern TV's and monitors. Although this is designed specifically for the H4 it will still work in original ST's but the HDMI would need an extension cable and an outlet out of the case.

So we started with @Smonson's work and mashed it with our FPGA Blitter board and looking to provide the HDMI port out where the monitor port is.

@Smonson as you may of seen in this thread has been working on patching TOS for resolution switching. This great work has been a major breakthrough and shows an ST doesn't need to swap cables to change resolutions. In the previous post you can see a video of using @Smonson board to test being able to switch into all three resolutions Low, Medium and High with the HDMi board. This is the ultimate out for video on the STFM.

Mashing up the Blitter FPGA:
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Fitting the board to the H4 monitor port location:
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Seeing how the board would look and if it fits:
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How would the HDMI fit and look in the case monitor port:
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And this is the first board we had made that fits the space. Spot the SEC booster as well in the H4:
IMG_4841 (1).jpeg
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The board with HDMI socket placed to see how it looks:
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Some 3D renders of the board:
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We have several boards at the assembly firm but unfortunately they are still there during the lockdown:
image0-2.jpeg (832.92 KiB) Viewed 1417 times

Our next phase is to test the boards out and once working reduce the design and include audio out through the HDMi as well. The full size Max10 is pretty large so we will look at the smaller form factors to reduce the size of the board.

Re: Project: HDMI/DVI out for STFM

Posted: Sun Apr 19, 2020 12:14 am
by Icky
I've just realised I haven't named this board yet. Hmmm. Thinking cap on.