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Forum Index : Microcontroller and PC projects : Problem with VGA video output PicoVGA
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Mixtel90 Guru  Joined: 05/10/2019 Location: United KingdomPosts: 5712 |
I love that SSD1963 emulation! I'd forgotten that. The Pi Zero would be ideal, but only seems to be available as the 15 UKP Zero W now. :( Edited 2023-05-31 04:32 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 3650 |
Cheaper by far if it works would be this (choose the VGA -> HDMI one) John |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5712 |
That looks interesting... Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 3506 |
Hi Nick, I checked the VGA timing (focus on the vertical timing since you see blurring on the rigt side of the screen). There is some improvement possible, but that does not relate to the problem you see. See attached vga.zip Did you achieve any improvement with the 47 ohm resitors in HSYNC and VSYNC on that failing monitor ? Regards, Volhout Edited 2023-06-01 02:13 by Volhout PicomiteVGA PETSCII ROBOTS |
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nbrok Regular Member  Joined: 13/02/2023 Location: NetherlandsPosts: 59 |
I'm waiting of the delivery of the newest version of my VGA PCB's so I could not test it yet. I could on an old 4.3 TFT monitor adjust the phase and the problem is gone but on modern monitors you cannot change the phase.... Greetings, Nick de pe1goo |
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| nbrok Regular Member Joined: 13/02/2023 Location: NetherlandsPosts: 59 |
@volhout I've received the PCB the 47 Ohm resistor does change something and the phase is better adjustable now... I've picovga working on 2 different monitors now. I have to change the phase value in each monitor. The picture is acceptable now. Without the resistor it also works, but adjustment is a little more difficult. Greetings, Nick de pe1goo |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 3506 |
Thanks, I will modify my units too, and observe the effect. Volhout PicomiteVGA PETSCII ROBOTS |
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| nbrok Regular Member Joined: 13/02/2023 Location: NetherlandsPosts: 59 |
Geoff, Could you add a line in the picovga documentation about adjusting the Phase of your monitor in VGA mode when in mode 1 a line isn't displayed as sharp as expected? You have to do the adjustment until all characters on a line are even sharp. Also in the example connection of the VGA connector, the two 47 Ohm resistors in the vsync and hsync lines could be added. The effect I discovered could be to do something with VGA cable length and quality. But this info will help those people who have the same problem as I had.  Greetings, Nick de pe1goo |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 5712 |
To be honest, I don't think I've ever had any sort of Phase control on any of my VGA monitors to date. I'd never even heard of it until this thread. I am now educated. :) I'm going to include the series terminating resistors on the synch signals on PicoGAME Alpha as they work nicely into the layout. :) I've ordered a couple of VGA-RJ45 adapters from ebay (4.40 UKP for two, including postage)) to test the viability of CAT5 for VGA. I'm not anticipating any problems at the resolutions we use - it may even be an improvement over the cheaper VGA cables. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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