Atom Video to HDMI Adapter

[etaoin]

https://nl.farnell.com/camdenboss/crdcg ... dp/1171635

[-B-]

That looks very close. If anyone goes for that, please show us the end result.

Neil.

[hoglet]

Hi Roland,

Thanks for the offer, I have as well but the Dutch Farnell doesn't seem to have it in their catalog.
I can check the UK site.

I believe this CamdenBoss CRDCG0003 case is identical to the Evatron EVA73G:
https://nl.farnell.com/camdenboss/crdcg ... dp/1171635

But it's worth you double-checking the dimensions, particularly the PCB mounting points.

Dave

[etaoin]

That looks very close. If anyone goes for that, please show us the end result.

Neil.

It is the one I got and the pcb fits. You need to cut two bits of plastic inside but I think the original one needs that as well.

[etaoin]

It is the one I got and the pcb fits. You need to cut two bits of plastic inside but I think the original one needs that as well.

Including the five mounting points, I might add. So it seems to be identical. And I got it from earlier in the thread, so someone already mentioned it there.

[-B-]

It is the one I got and the pcb fits. You need to cut two bits of plastic inside but I think the original one needs that as well.

Including the five mounting points, I might add. So it seems to be identical. And I got it from earlier in the thread, so someone already mentioned it there.

Excellent! If I ever build another, I know I can get them elsewhere. And yes, you do have to remove the small ribs inside the box on the two longer sides. Also, if you make the IDC cable with a strain relief bracket, you need to remove one of the centre screw posts in the bottom too.

Sinuss.nl appear to be a Farnell reseller. You can search their site with Farnell codes. They add a little on to the price but at least you can get stuff in a couple of days (my box from eBay took two and a half weeks!).

Neil.

[bprosman]

Let me check , but let's build PCB first.
Hoping to have the parts arrived this week.

They add a little on to the price but at least you can get stuff in a couple of days

Well , I checked that earlier this week but a 8051 core processor was 7 Euro , versus 4 Euro directly at Farnell (VAT excluded).
But I do have a company account at Farnell.

[bprosman]

Got an e-mail from Farnell that they run out of stock for the TI version of the LM319 and then its over (220 in stock).
They recommend ON Semi.

@Dave , any experience with that brand ?

[hoglet]

Got an e-mail from Farnell that they run out of stock for the TI version of the LM319 and then its over (220 in stock).
They recommend ON Semi.

@Dave , any experience with that brand ?

No, the only one's I've tried are TI and ST.

I have no reason to believe there will be problems with the OnSemi version, it's just I haven't personally tried them.

BTW, Phill reported issue with the Fujitsu version on his colour board. That's the only data point I have.

Dave

[-B-]

I paid 33cents each for mine from Reichelt and it was pot luck whether I received, ST, Philips, Fairchild or Samsung.

I received Fairchilds both times and they work fine.

Neil.

[etaoin]

Ok, back from holiday, so finished the converter.

By the way, I used an lm2950-33 instead of the LE33CZ, as I had that lying around.

[hoglet]

I have no reason to believe there will be problems with the OnSemi version, it's just I haven't personally tried them.

Well, I have now, and the OnSemi LM319N work perfecty.

They seem more widely available that the TI parts and are cheaper: 41p compared to £1.50 at Farnell:
https://uk.farnell.com/on-semiconductor ... dp/2450778

Dave

[anightin]

Dear All,

I seem to have inadvertently broken my previously working Atom Video to HDMI Adapter

When it Syncs I now get this on the display on both my ATOMs (reverting back to composite reveals the ATOMs are both running as normal)

Note that I did press the menu button and went to the info menu -- hence the Calibration text.

Booting the SD card to the Stardot ATOM software archive changes the white border to green but that's about it.

Was just wondering if the above would give any clues as to where to start debugging?

Many thanks

Andy

[hoglet]

A couple of quick checks with the HDMI Adapter connected to the Atom, to make sure the Atom really is running

1. Hit BREAK

2. Blind type ^G <Return> and make sure it beeps (twice, once on the ^G, once on the Return)

3. Blind type CLEAR 4 <Return> - is there any difference to the screen (no beep should happen)

4. Blind type CLEAR 0 <Return> - is there any difference to the screen (no beep should happen)

Assuming that's all as expected, then I would start to invesigate the luminance path.

I can get the same display by adjusting RV1 fully clock wise. Note the initial position of RV1, and try adjusting it fully anti-clockwise. Does anything change? If not, this suggests the Y signal seen by the Pi is stuck high, due to a upsteam of this.

Do you have a scope?

I would start by checking the signals on pins 4, 5 and 12 of U4. That should help narrow down where the problem is.

The full schematic is here.

Dave

[anightin]

Hi Dave,

Thanks for the quick reply. Have been out today so just had a quick look again.

BTW the other board I built up worked first time so at least I have two to compare now although I am waiting for a set of LM319N's so sharing between the two boards at the moment

1. Hit BREAK
2. Blind type ^G <Return> and make sure it beeps (twice, once on the ^G, once on the Return)

I get 2 beeps, and swapping to my new-build version works fine

3. Blind type CLEAR 4 <Return> - is there any difference to the screen (no beep should happen)

4. Blind type CLEAR 0 <Return> - is there any difference to the screen (no beep should happen)

With CLEAR 0 I get green blocks where character should appear at least.


Adjusting RV1 has no notiable effect -- I even desoldered RV1 and RV2 and swapped them over to check


I will see if I can borrow a scope later or tomorrow to check the signals -- note again that the IC works fine in my other build so I can rule that out at least.

Kind Regards

Andy

[hoglet]

Have you tried swapping the ribbon cable?

A useful measurement with a volt meter would be to measure the voltage between Pin 5 of IC4 and ground. Measure this with RV1 at each extreme. It should read ~0.8V at one extreme and ~2.5V at the other extreme.

Then measure the voltage across R7 - it should be ~1.0V

[anightin]

Have you tried swapping the ribbon cable?

Yes both cables work the same on the working and non working boards:

A useful measurement with a volt meter would be to measure the voltage between Pin 5 of IC4 and ground. Measure this with RV1 at each extreme. It should read ~0.8V at one extreme and ~2.5V at the other extreme.

Working board:
Pin 5 : 0.8v and 2.48v

Non-working board:
Pin 5 : 179mv and 0.6V

Maybe a clue?

I notice on the working board, I start to loose the picture at around 1.2v so explains why RV1 is making no noticeable difference on the non-working board.

Then measure the voltage across R7 - it should be ~1.0V

~1.0v on both boards

[anightin]

Eureka! Found the culprit!

It was C7 that decided to go from a 100nf to a 0.6nf Capacitor!

Thanks for steering me in the right direction again Dave. I enjoyed the learning experience



Much apprecaited as always.




Right, once my comparators arrive, I can now run each ATOM side by side with it's own HDMI interface.

[hoglet]

Non-working board:
Pin 5 : 179mv and 0.6V

If you look at the schematic, R7/RV1/R8 are just a simple voltage divider.

So this suggests either the 3.3VA supply is dodgy, or there is a problem with R8.

Then measure the voltage across R7 - it should be ~1.0V

~1.0v on both boards

This suggests the 3.3VA supply is OK.

I'd investigate around R8. Look for dry joints.

Dave

[anightin]

Non-working board:
Pin 5 : 179mv and 0.6V

If you look at the schematic, R7/RV1/R8 are just a simple voltage divider.

So this suggests either the 3.3VA supply is dodgy, or there is a problem with R8.

Then measure the voltage across R7 - it should be ~1.0V

~1.0v on both boards

This suggests the 3.3VA supply is OK.

I'd investigate around R8. Look for dry joints.

Dave

As per above it was C7, I guess the next question is why did it fail?

[hoglet]

As per above it was C7, I guess the next question is why did it fail?

Glad you found that.

This is quite unusual....

Did it fail short circuit? Can you measure it's DC resistance with a meter?

Where did you buy them from?

Dave

[anightin]

Did it fail short circuit? Can you measure it's DC resistance with a meter?

Unfortunately it's now in the gloop at the bottom of the dustbin but I'm pretty sure it had failed near short-circuit.

All voltages are back where they should be with a now different brand of cap.

I got the dodgy one from eBay (where else for dodgy components I guess )...

https://www.ebay.co.uk/itm/102-822-50V- ... 3864382196

Regards

Andy

[Elminster]

Finished the board a while ago, finally got around to ordering the case, and got it the other day (also ordered one that fits the smallymouse2 at the same time). DoH! Reading the instructions I should have marked the drill holes before populating the board.

So I think plan B is to create a to-scale template from the pcb file and use that. Just checking no one created that before I start messing about in kicad.

[bprosman]

So I think plan B is to create a to-scale template from the pcb file and use that. Just checking no one created that before I start messing about in kicad.

Doesnt require much messing. Printing the Kicad Design is pretty well to scale on a laser or inkjet printer.

[Elminster]

Is it me? or do the pcb layout for kicad atom on github don't look right, the orientation seems sideways.

[hoglet]

Is it me? or do the pcb layout for kicad atom on github don't look right, the orientation seems sideways.

Not sure what you mean - can you post an image or a photo?

[Elminster]

If it’s the right version it must be me then. Will have another look but I am not really a kicad expert. I might give up on template idea and just try and measure it.

[hoglet]

If it’s the right version it must be me then. Will have another look but I am not really a kicad expert. I might give up on template idea and just try and measure it.

Ah, It looks like the lastest Atom PCB is on the dev branch:
https://github.com/hoglet67/RGBtoHDMI/t ... ad_atom/v2

Dave

[Elminster]

Ah yes. Thanks. That looks better. I thought I was doing something wrong in KiCad, I didn't scan the dev branches on Github.

So Switching off all the layers except B.Mask and Edge cuts. Hopefully gives me enough to print and get the Dremel out.

[-B-]

.... or someone could measure their box when they get home from work tonight and post the results here?
(I am volunteering).

Neil.