Project: HDMI/DVI out for STFM

Progress on our FPGA cores.
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Smonson
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Re: Project: HDMI/DVI out for STFM

Post by Smonson »

Haha, I'm sure my boss would love it, and everyone under 30 would be confused!
ijor
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Re: Project: HDMI/DVI out for STFM

Post by ijor »

So it is a powering issue indeed. Too bad Smonson can't yet reproduce it.

I still don't see however, how glitches, ringing, or gnd noise would produce the exact symptoms we see. According to the tests, at least for some of the readings, the bidirectional level shifter is not driving the bus at all. So whatever is happening, lasts at least for a full cycle. May be there is a combination of issues, or may be the tests are misleading somehow.

One thing that might make some sense, is that the FDIR signal is not being recognized as a high level. If the voltage level doesn't quite reach the minimum requirement for a high level (2V), the result might depend on the current VCC level of the chip. That might conceivable explain why it works with lower system 5V voltage. And the lower system voltage might not affect the FDIR signal itself because the FPGA power is regulated.

The FDIR signal looks quite healthy on Smonson's scope. But it might be different for some reason on other systems. So some additional scope measurements could be very useful. But they have to be done on a failing system and on a failing cycle. And scope ground should be connected at the daughter board.

A possible idea to confirm if the problem is the voltage level at the transceiver, could be to insert a diode between the chip VCC pin and the pad? Not sure how difficult would be to do that because of how the HDMI dual board is made.

May be there is a gnd problem at the transceiver that it's affecting? This chip has multiple gnd pins.
http://github.com/ijor/fx68k 68000 cycle exact FPGA core
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Smonson
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Re: Project: HDMI/DVI out for STFM

Post by Smonson »

exxos wrote: Thu Dec 06, 2018 11:42 am As a mad idea, could you double the length of your ribbon cable on your board and try tests again ? Make sure PSU is at 5V or even 5.2V.
It worked perfectly for at least ten minutes with a 10cm cable (no bad reads) - when I increased it to 12cm it wouldn't even boot up once. Crashes immediately with garbage on the screen, or three bombs.
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Re: Project: HDMI/DVI out for STFM

Post by exxos »

Probably the 32MHz line gets to noisy with the longer cable. Annoying you couldn't replicate the fault. Will have another think.
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viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
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Re: Project: HDMI/DVI out for STFM

Post by ijor »

Any news? Hope this will fully working on 2019! :)
http://github.com/ijor/fx68k 68000 cycle exact FPGA core
FX CAST Cycle Accurate Atari ST core
http://pasti.fxatari.com
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Smonson
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Re: Project: HDMI/DVI out for STFM

Post by Smonson »

This is kind of on hold at the moment - I need to get my hands on one of these machines with the resetting behavior.
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Re: Project: HDMI/DVI out for STFM

Post by exxos »

I think how it was left, was I suggested to Icky he send me his board to see if it worked in the same machine as mine does. At least then we should know a little more of where the problem is.. hopefully.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Smonson
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Re: Project: HDMI/DVI out for STFM

Post by Smonson »

If you guys have got enough motivation left to do that, then that would be awesome. I suspect that the problem is in the machine rather than the DVI board, though. All the boards were tested on my machine before I sent them out, and Troed had the same problem with 2 different DVI boards.

Hey, random question: who has a machined-pin IC socket under their shifter and who had a cheaper blade style socket? I have machined pin myself. I think they have a higher rated current capacity - perhaps they also have lower contact resistance.
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Re: Project: HDMI/DVI out for STFM

Post by exxos »

All mine are blade types. Though I have had problems with those round header pins as well. I keep having to wipe them with IPA to get my boosters working. They don't look dirty and I'm hardly thouching them either... I'm assuming icky and troed have splashed some IPA about on it all...

Its hard to think what's going on. Though I think icky has tried a real stfm and the remake stf. So granted there are differences on various revisions of motherboards, the stf remake should have worked better than a normal stfm. So I'm leaning towards more of some problem on the FPGA board.

Again I'm assuming the FPGA board has been dismantled and IPA put on all the pins by troed and icky..

There still might be a bad solderjoint somewhere. I had a bad joint on one of the diodes on a PSU earlier. Looked fine, even metered out just fine everywhere..and yet the PSU malfunctioned because of a bad solder joint. I resoldered all 4 diodes and its working fine now. So its easy to get caught out.. There may be a bad solder on the FPGA itself..
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
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Re: Project: HDMI/DVI out for STFM

Post by Icky »

I have a working STFM arriving in the next few days so will try the board out on that one too. If I am still having issues I will send my DVI board to exxos to check on his STFM to see if it is working there.
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