Project: HDMI/DVI out for STFM

General discussions or ideas about hardware.
User avatar
Icky
Trusted Guru
Trusted Guru
Posts: 859
Joined: Sun Sep 03, 2017 10:57 am
Location: UK

Re: Project: HDMI/DVI out for STFM

Post by Icky » Sat Jan 05, 2019 6:46 pm

exxos wrote:
Fri Jan 04, 2019 9:38 pm
Icky wrote:
Fri Jan 04, 2019 6:07 pm
At least we are consistent :)

So interestingly from my testing I see the following traits
Very odd..

Add this cap and I bet you be working fine...


viewtopic.php?f=29&t=330&start=270#p14777
Out of interest what value did you use?

User avatar
Icky
Trusted Guru
Trusted Guru
Posts: 859
Joined: Sun Sep 03, 2017 10:57 am
Location: UK

Re: Project: HDMI/DVI out for STFM

Post by Icky » Sat Jan 05, 2019 8:06 pm

Icky wrote:
Sat Jan 05, 2019 6:46 pm
exxos wrote:
Fri Jan 04, 2019 9:38 pm


Very odd..

Add this cap and I bet you be working fine...


viewtopic.php?f=29&t=330&start=270#p14777
Out of interest what value did you use?
10nF actually made the board not work - black screen.

47pF works fine.

Screen is now stable on STFM.

EDIT: Just tried the HDMI board back in the STF Remake and 520ST with the 47pF cap in place and its even more temperamental. Some times its just a blank screen like when I used the 10nF when in the STFM and not very often it might try to boot and of course reset. On reset it mostly goes back to blank. I guess the 16MHz line is not so happy in these two machines with the cap on it.

User avatar
exxos
Site Admin
Site Admin
Posts: 5408
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Project: HDMI/DVI out for STFM

Post by exxos » Sat Jan 05, 2019 9:01 pm

Icky wrote:
Sat Jan 05, 2019 8:06 pm
10nF actually made the board not work - black screen.

47pF works fine.

Screen is now stable on STFM.

EDIT: Just tried the HDMI board back in the STF Remake and 520ST with the 47pF cap in place and its even more temperamental. Some times its just a blank screen like when I used the 10nF when in the STFM and not very often it might try to boot and of course reset. On reset it mostly goes back to blank. I guess the 16MHz line is not so happy in these two machines with the cap on it.
Anything over about 390pF will squash the signal to much. Its not a good fix, but I still suspect its a clocking 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

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

User avatar
Smonson
Posts: 215
Joined: Sat Oct 28, 2017 10:21 am

Re: Project: HDMI/DVI out for STFM

Post by Smonson » Sun Jan 06, 2019 7:56 am

I used 22pF on the new boards. It's been working fine for my machine. The best place to solder them in is underneath the 34-pin IDC cable pins - pin 1 being the clock, and any of the surrounding pins being ground.

Speaking of the new boards, I have 3 built now (the shifter socket adapter boards, that is) from the Schmitt trigger design, each tested for 30min. I'll be sending these out shortly to the three of you who have given me your postal address. These should hopefully give you a better clock signal.

User avatar
Icky
Trusted Guru
Trusted Guru
Posts: 859
Joined: Sun Sep 03, 2017 10:57 am
Location: UK

Re: Project: HDMI/DVI out for STFM

Post by Icky » Sun Jan 06, 2019 10:28 am

Smonson wrote:
Sun Jan 06, 2019 7:56 am
I used 22pF on the new boards. It's been working fine for my machine. The best place to solder them in is underneath the 34-pin IDC cable pins - pin 1 being the clock, and any of the surrounding pins being ground.

Speaking of the new boards, I have 3 built now (the shifter socket adapter boards, that is) from the Schmitt trigger design, each tested for 30min. I'll be sending these out shortly to the three of you who have given me your postal address. These should hopefully give you a better clock signal.
Thanks Smonson. I think I will try a lower value 22pF as you have used to see if it still works in the STFM and then see if its effect in the 520ST.

Post Reply