Project: HDMI/DVI out for STFM

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exxos
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Re: Project: HDMI/DVI out for STFM

Post by exxos » Wed Dec 05, 2018 11:40 am

I've made a suggestion to icky, that once he's done tests, to loan me his HDMI board to test in my machine..

But so far, It seems like its only failing in stm machines?
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Project: HDMI/DVI out for STFM

Post by troed » Wed Dec 05, 2018 11:44 am

exxos wrote:
Wed Dec 05, 2018 11:40 am
But so far, It seems like its only failing in stm machines?
520 STM and 1040 STFM (SMT rev) here. It's on my todo to run it on a 1040 STF (red led old model) and a few Mega STs. I'm really sorry for not being able to allocate more time to it atm ...

/Troed

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Re: Project: HDMI/DVI out for STFM

Post by exxos » Wed Dec 05, 2018 12:37 pm

One thing I'm not following, is if there is a drive problem on D9, why would it work on some boards but not others?

I don't know about FPGA , but on pld chips they have input only pins which can catch you out sometimes.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Project: HDMI/DVI out for STFM

Post by Smonson » Wed Dec 05, 2018 1:07 pm

troed wrote:
Wed Dec 05, 2018 11:44 am
I'm really sorry for not being able to allocate more time to it atm ...
Don't be, it's awesome that you've already done so much to help.
exxos wrote:
Wed Dec 05, 2018 12:37 pm
One thing I'm not following, is if there is a drive problem on D9, why would it work on some boards but not others?
Just another piece in the puzzle. What I know is, none of the boards I've made (maybe 8 or 9) have exhibited this behaviour on my machine (I tested them all); and of the 4 that have been tried by other people so far, 3 of them have developed the resetting problem after being installed into their new home. And in Troed's case that has happened twice in a row. So it seems to be ST specific behaviour and not mod board specific - so far.

Hmm, incidentally, Exxos are you running a stock power supply in your test machine? I have a stock PSU, I think Troed has a modern replacement. My 5v level is actually about 4.7v. Dunno if it could be connected but couldn't hurt to rule it out...

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Re: Project: HDMI/DVI out for STFM

Post by troed » Wed Dec 05, 2018 1:10 pm

Smonson wrote:
Wed Dec 05, 2018 1:07 pm
Hmm, incidentally, Exxos are you running a stock power supply in your test machine? I have a stock PSU, I think Troed has a modern replacement. My 5v level is actually about 4.7v. Dunno if it could be connected but couldn't hurt to rule it out...
My 520STM runs off a picoPSU and the 1040STFM off a recapped original PSU - at 5.1V or so (helps with the overclocking). It's an SR98 so I can always lower it.

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Re: Project: HDMI/DVI out for STFM

Post by exxos » Wed Dec 05, 2018 1:41 pm

Smonson wrote:
Wed Dec 05, 2018 1:07 pm
Exxos are you running a stock power supply in your test machine? I have a stock PSU, I think Troed has a modern replacement. My 5v level is actually about 4.7v. Dunno if it could be connected but couldn't hurt to rule it out...

I have my own brand PSU & a re-cappd SR98.. both will be outputting 5V, but don't which one I used.. Will try and test both when I get home later, but won't be until around 10pm.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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Re: Project: HDMI/DVI out for STFM

Post by ijor » Wed Dec 05, 2018 2:14 pm

exxos wrote:
Wed Dec 05, 2018 12:37 pm
One thing I'm not following, is if there is a drive problem on D9, why would it work on some boards but not other?
Well, I don't know for sure of course. It doesn't seem to depend on the chipset. It doesn't seem to be a timing issue. It could be a functional issue, such as a bug in the Verilog code. But doesn't seem very likely that a bug would affect some computers and not others.

So I was thinking it might be perhaps a powering issue. Voltage level, ground noise, etc, this could change depending on the computer, right?

Note that I didn't mean it could be a drive problem on D9, but a drive problem on the FDIR signal. FDIR is the signal that controls the bidirectional level shifter.
I don't know about FPGA , but on pld chips they have input only pins which can catch you out sometimes.
Yes, the FPGA also has input only pins. But the compiler would not allow you to put output or bidirectional signals on input only pins.
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Re: Project: HDMI/DVI out for STFM

Post by exxos » Wed Dec 05, 2018 2:50 pm

I have been thinking along the lines that the stm if failing more than the stfm could be a power issue.
4MB STFM 1.44 FD- VELOCE+ 020 STE - 4MB STE 32MHz - STFM 16MHz - STM - MEGA ST - Falcon 030 CT60 - Atari 2600 - Atari 7800 - Gigafile - SD Floppy Emulator - PeST - HxC - CosmosEx - Ultrasatan - various clutter

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https://www.exxoshost.co.uk/atari/last/storenew/ - All my hardware mods for sale - Please help support by making a purchase.

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Re: Project: HDMI/DVI out for STFM

Post by Gunstick » Wed Dec 05, 2018 4:34 pm

ijor wrote:
Wed Dec 05, 2018 1:41 am
You didn't specify how you are reading the bus capacitance. If you are just reading from unpopulated RAM space, then this doesn't depend on Shifter at all.
It's the classic setting of the screen start address outside of physical RAM. Usually you see noise, but in fact that noise is the bus activity. If you do that in a fullscreen, the noise is just a static pattern because all activity is synchronized.

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Re: Project: HDMI/DVI out for STFM

Post by czietz » Wed Dec 05, 2018 4:52 pm

Just another (probably crazy) idea: On a different plug-in board that I recently worked on, there was a big problem with ground bounce. Modern, very fast CMOS output drivers can inject a short but intense burst of current into ground while switching logic levels. Combined with the inevitable inductance of the ground traces and pin/socket connections, a momentary shift of the ground level of the plug-in board (respective to the Atari mainboard ground) happens.

In case of the board that I mentioned, this ground bounce was several volts! This caused an input signal that was supposed to be "high" (5V referenced to the Atari mainboard ground) to be only 1 - 2 V referenced to the plug-in board ground. Thus, this was registered by the circuit on the plug-in board as the signal seemingly glitching "low", causing malfunctions that were inexplicable at first.

One can even reason that this behavior depends on the Atari mainboard, because different revisions will have different ground tracing, different layout of the decoupling caps, etc.

Which ground was used for the scope traces posted in this thread? Do the traces look different if another ground point is used?

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