VGA through rpi pico - How many colors possible on border?

[Brocky]

still getting green?
its really a simple circuit it should work easily...
do you have an oscilloscope to check the inputs and outputs of the comparators, and then to the pico?

maybe the plug and wires out to the board are wired wrong at the 6 pin din youre plugging into the cpc?

[eto]

I'm really stuck here.

can you take close pictures of the whole set-up? At least one of the full PCB and one that shows the pins of the monitor connector from the soldering side? 

[orzel]

Hello,

I'm interested in building one. Is there, by any chance, other people interested in France ? We could share pcb fabrication/shipping fees.

[Brocky]

Hello,

I'm interested in building one. Is there, by any chance, other people interested in France ? We could share pcb fabrication/shipping fees.

it cost me like $5 to get 5 boards made and posted to australia from PCBway

[orzel]

That would cost at the very least twice as much from here. But indeed, still less expensive than I thought. I'm more used to 10cmx10cm at jlpcb
Still, if anybody from France wants to pay 1/5th of that, just contact me.

[orzel]

I've moved the proposal to (French speaking) system-cfg.com forum. I propose there the PCB  with or without the 3 converters. The remaining of the bom is easy to source.

But if anyone here still wants one of those, you can contact me in PM and in English. I could probably ship in Europe for not much more than France. Other countries would be complicated, both for payements and shipping. But noone uses CPC outside of Europe, right ?

[eto]

The components might be the most interesting part to share an order.

5 PCBs can be ordered at JLCPCB for 6€ including shipping to Germany. I would expect (but don't know) that it's similar all over Europe.

But at least the comparators need to be ordered at one of the big distributors and shipping will add a lot of cost if you don't order enough to get over the free shipping threshold.

Therefore it might make sense to offer full sets to people who are interested not just the PCBs. That's what I did a few times (other projects) and people appreciated that a lot.

[orzel]

Yes, the comparators need to be bought from big distributors with huge 'minimal' command for free shipping, that's why i offer that. But the whole kit would be a lot harder to do : source all components requiers a lot more time, and also it's more complicated/expensive for shipping. While pcb and comparators can be put in cheap standard letters.

There's not enough interest for this.

[eto]

source all components requiers a lot more time,

The Github repository has links to almost all components on Digikey. 

[orzel]

I've noticed.

And ? I don't see your point.

It still requires lot of times, requires a lot bigger upfront money investment, and it still is a lot more complicated/expensive to ship.
I still don't wanna do that, especially with so few potential people interested.

[Brocky]

I've noticed.

And ? I don't see your point.

It still requires lot of times, requires a lot bigger upfront money investment, and it still is a lot more complicated/expensive to ship.
I still don't wanna do that, especially with so few potential people interested.

i could sell you a spare complete board i have, or the one i have without the vga connector (i didnt order enough!)
but shipping from australia to france isnt going to be cheap...

i ordered 5x the components (including the picos) from digikey all in one order just over the $60 threshold to qualify for free shipping...

[eto]

It still requires lot of times, requires a lot bigger upfront money investment, and it still is a lot more complicated/expensive to ship.
I still don't wanna do that, especially with so few potential people interested.

I answered only to your comment that it would be hard to source all components.

I totally understand that you don't want to spend money upfront. 

[orzel]

i ordered 5x the components (including the picos) from digikey all in one order just over the $60 threshold to qualify for free shipping...

Yeps, too bad. France is as far as it can be from australia 

That's about the prices I have for 5x indeed. I agree it's not a huge saving, but quite some people prefer to pay 1/5 of that..

[rastislavz]

I have got the parts from the shop yesterday and comparators were enclosed in a separate bag on which it was written that humidity sensitive devices are inside and that it should be opened just before soldering. What it is about, how can the humidity harm chips? Only thing I can think about is that chip legs can be oxidized but it should not be specific just to the comparators. 🤷

[rastislavz]

I have built mine VGA4CPC and I have tested it on my Fujitsu-Siemens Scenicview XE17-2 monitor I have found on the scrapeyard. For now just without the CPC, I have yet to solder the RGB cable to the CPC (would be nice to have a R/G/B written on the PCB silckscreen). Monitor works with both frequencies - 50.1 and 60.4 (btw it would also be nice to have a frequency stated on the PCB silkscreen), on both it reports the 800x600 resolution.
But it has a problem drawing properly the whole screen on 60.4Hz, in some parts the vertical lines are not straight but it is a "shaky" - see enclosed image. I suppose it is a problem of a monitor because when I let it to run autosetting it sometimes has a problem in the corners and sometimes in the centre of the picture.

[Brocky]

I have built mine VGA4CPC and I have tested it on my Fujitsu-Siemens Scenicview XE17-2 monitor I have found on the scrapeyard. For now just without the CPC, I have yet to solder the RGB cable to the CPC (would be nice to have a R/G/B written on the PCB silckscreen). Monitor works with both frequencies - 50.1 and 60.4 (btw it would also be nice to have a frequency stated on the PCB silkscreen), on both it reports the 800x600 resolution.
But it has a problem drawing properly the whole screen on 60.4Hz, in some parts the vertical lines are not straight but it is a "shaky" - see enclosed image. I suppose it is a problem of a monitor because when I let it to run autosetting it sometimes has a problem in the corners and sometimes in the centre of the picture.

like i mentioned.. its still somewhat monitor dependant.. not all monitors are going to work perfectly.. some allow wide range of "off" refresh rates, where others produce images like you have when they are slightly "off" exactly 50/60hz..

the 60hz switch isnt really needed tbh... it just makes it more compatible with more monitors..the CPC only outputs 50hz

also, theres no scanlines visible on LCD/LED monitors.. the "shaky" off pixel lines are usually hidden behind the scanlines

[orzel]

the 60hz switch isnt really needed tbh... it just makes it more compatible with more monitors..the CPC only outputs 50hz

I completely (but respectfully) disagree. It's really a great feature to be able to handle both 50Hz (better when it works) and 60Hz (when you can't do otherwise). And it's another really great feature to be able to switch/test so easily.

[rastislavz]

Fortunately my monitor is displaying basically perfect picture on 50Hz, in 60Hz I have this, as shown above, "toothy" picture in some parts and also on 60Hz image is not centered vertically but it is positioned in the bottom of the display with black bar on the top.
So I am happy with the 50Hz and do not need to consider 60Hz at all.

I have 5 PCB's from JLCPCB. I have fully built one to confirm everything works as it should but I will be redesigning the board to fit more my needs and my idea how it should look:

1. will add D-SUB9 connector for connecting video input from CPC - I will make a cable from DIN6 to D-SUB9. I want to have it disconnectable and because tiny wires soldered directly to the PCB can break easily. Reason why D-SUB9 instead some other, e.g. DIN6 is because it is widely available and cheap and can be attached firmly with the screws. Perfect would be some XLR or DIN with bayonet locking but these are hard to find, expensive and mostly made to be mounted on the panel not soldered onto the PCB. But if somebody knows about some better option...
2. I will add power barrel jack pasthrough so that I can use the CPC power supply to power it
3. I do not like capacitors sticking out around the comparators and since comparators are already SMD, I will put the SMD capacitors in 1206 package, should not be hard to solder these as well.
4. I do not like Pico soldered directly, so I will add the THT socket instead for the Pico - anyway the highest component here is the VGA connector so there is enough space. also all SMDs will go on the bottom side of the PCB under the Pico
5. some other cosmetic stuff like using resistor packages instead individual 47 and 75 resistors.

So I'll be giving away these 4 spare boards if somebody like to have them. One has already comparators soldered in (I could add the rest of the components for few beers :-) ). I will give away later also the fully built board when I build my modified version.

[orzel]

I don't understand your point '5'. You mean using resistors "networks"  ? For only 3 of them ... ?

I also have a modified version of VGA4CPC here.

May I suggest changing the voltage divider for 600mV : I've switched to 1k for R14 and 220 for R15. This has several advantages:
* it uses less current : 27mA is expensive just for a voltage reference
* one resistor reference less : 22ohms is not used anywhere else, while 1k and 220 are already present in the BOM.

[rastislavz]

Yes, pardon my English - I ment resistors networks. And yes only for 3 of them but twice so all in all just 8 solder points instead 12. And saves a bit of space. 😁 Thats why I marked it as a cosmetic stuff. 🙂
Yes I saw your issue on the github regarding resistors on. 600mV line, I will change it accordingly for sure.

[orzel]

I had forgotten about the issue !

The original author seems to have vanished. He doesn't answer on PM on this forum or on github... Too bad, he did a great job.

[rastislavz]

True he did. I just hope he just lost the interest and he is otherwise OK.