Has anyone tried on of the VGA adaptors on a Pi?

I know CPC have a few, but I was wondering what kind of results they get? I have an application where I could probably retire a PC from a shop display function, and drop a pi in place - but it would need to drive an existing active VGA splitter to feed a couple of monitors...

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John. 
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John Rumm
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I have one, which works fine. For me, it correctly found the resolution of the attached monitor, but there is lots of advice on editing the config file for cases where this doesn't happen.

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Alan Adams, from Northamptonshire 
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Alan Adams

In a mad moment - Alan Adams mumbled :

Yes! I am using one of the Lump-on-the-end-of-an-HDMI-lead type. from Amazon at £10 (less a penny) Works a treat since I sorted out other problems [see below] that were confusing things. It seems not as versatile as the one the previous response seems to indicate, as it does not detect monitor information or output audio.

These are powered from the 5volt line in the HDMI system and may not give enough umph to drive a VGA splitter unless that is powered. I recommend that you power the Pi through a Powered USB Hub.

If you buy a 'Lump' one then I suggest you buy the slightly more expensive one which has an Audio jack socket on the side. Mine does NOT output Audio, tho' I may try a second modification if I really need sound.

[below] - What follows is nothing to do with the converter - [ A lesson - in something ?]

At first I could not get the thing to work - just got a flash of picture then nothing, (I am using an analog only TV with a 'PC' input socket) so I took the Pi to a set with HDMI input and tested - OK -

Ah! Must be low power, asked bod at Maplins about HDMI cables and was told HDMI does not have power. WRONG there is a 5 volt connection, see the magic Google for circuit diagrams, pinouts etc.

So at the risk of wasting £10 I pried the cover off and started prodding with voltmeter. After a bit of experimenting found two places to easily connect +5v and 0v, cut a spare USB -Blackberry charger lead (pound shop - £1) checked the pinout and soldered it in. Re-assembled it, connected the new power lead to the USB hub and switched on - - - Nothing, no change, waste of time. Or was it ? - Last desperate try!

Took it and the Pi and the powered usb hub down to the new TV and connected it all up via the TV PC input (by kind permission of SWMBO) and 'Hello' RiscOs all over the TV (other Os' are also available)

Back to the lair and ripped out ALL the video cables and the VGA switch box, brought them down to the posh TV (after her bed time ;) )

Result was that the original VGA lead that came with the old TV was not passing the higher frequencies and slightly lower signal level generated by HDMI, even though three other VGA output computers had displayed OK. This may have been due to the Ferrite Lump at the end.

There was another, longer, lead that caused problems, 2nd hand from

1990. When cut up was found to only have a single outer screen.

The final test was to re-connect the Pi to my old TV, using ALL my VGA leads and the Switch Box connected in series (about 20m in all)

Wonderful - Full display at all the resolutions I wanted to use and a lot that I have no current use for.

A final act was to disconnect the 5v. input to the converter that came from the Pi via the HDMI input cable. This was to guard against the chance of trying to back power the Pi via the extremely fine wire of the HDMI cable. Now the converter power is from the USB hub only.

I suspect that IF I had found the duff VGA cable first there would not have been any need to tamper with the converter. [here endeth the lesson]

Hope this helps you and anyone else who is struggling.

Bryn

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|)ryn [vans            mail to - BrynEvans@bryork.freeuk.com
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Bryn Evans

Got a cheap one from china on ebay. Needs an external 5v supply as the Pi can't supply enough on the hdmi to run it. Haven't got audio working yet, but I'll just use the 3.5mm jack for that. Seems to work ok, picks up monitor settings ok and provides correct edid data.

Cost £6.43.

BTW, the Pi won't back-power through HDMI as there is a diode to protect the Pi.

Reply to
Dom

In a mad moment - Dom mumbled :

So I see, but I hadn't found the Circuit Diag for the Pi when all this happened. Live and learn.

If you mean Audio from the Pi 3.5mm jack, as I understand it there is NO output there when an HDMI connection, like the Converter, is plugged into the Pi.

Please can you give the ref for the ebay item you bought?

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|)ryn [vans            mail to - BrynEvans@bryork.freeuk.com
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Bryn Evans

The HDMI->VGA adaptor claims to support audio via HDMI and has a 3.5mm socket. I can't get any sound out of that.

The audio from the Pi 3.5mm jack is fine.

Sure

formatting link

Price seems to have gone up a bit since I ordered mine, and it take the normal "forever" to arrive from China.

Reply to
Dom

I am using both of my Pis with HDMI out (via DVI) and audio from the 3.5" jack. They worked like that with no tweeking from the default SD image.

I'm not sure if it is because I am using HDMI to DVI (which doesn't have audio out) or if it would be present with a full HDMI connection.

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  BD 
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<me9

The VGA splitter is an active device in this case - 1 in 3 out. Its on the end of a 15m VGA lead, and feeds a couple of TVs in a shop window. Historically, they needed to run a windows specific app on the PC for the display, but these days just need to run a looping promo video. So in recent times I have had good success just strapping a model A pi to the back of the TV, powering it from the TVs USB port and driving it via a short HDMI. In this case it might be easier to just reuse the existing cabling and infrastructure, but hence the need for VGA.

For this particular situation it can have its own dedicated PSU

I don't actually need sound in this case.

Although I am not sure exactly what benefit it gets from having it in the HDMI adaptor in most cases anyway. Since VGA does not carry audio, you either take your audio directly from the 3.5mm jack on the pi, or squirt it up the HDMI and then take it from the 3.5mm jack on the converter. If they are right next to each other, it makes little difference I guess. Might be handy if the converter is on the end of a long HDMI lead though.

[snip tale of cable woe]

Yup, dodgy leads can catch you out at the most unexpected times.

Had a similar problem the other day with a laser printer that was not appearing on the network. Checked it connected direct to a PC, fine. Tried patching the network socket to a different port on the switch, no different. Got the network tester out and checked both wall ports back to the patch panel, also fine. Though Ha, only thing left is the patch lead from switch to patch panel, replaced that, still no joy. Scratched my head for a bit did some more tests, and then at some point made the patch connection using one of my short patch leads I use with the tester, and it all sprang into life. Finally actually tested the original patch lead on the tester, duff. Checked the new replacement I had tried, equally useless. Got out a third new patch, tested that and it was fine. Put it in, all working.

(got a nasty feeling that was a bunch of patch leads bought on price - moral there as well!)

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Cheers, 

John. 
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John Rumm

Bad connections come first from dirt, worn, damaged (bent or missing pins), followed by cable failure (normally close to a "strain relief"), next is power. Those three things will cover 95% plus of faults involving joing bits of kit together with cables.

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Cheers 
Dave.
Reply to
Dave Liquorice

I bought a cheaper HDMI to VGA converter from China via Ebay. It didn't seem to have any way to transmit EDID information (or whatever is used with HDMI) back to the RPi from an older VGA monitor, nor from a large Optiquest monitor, so it was unusable until I found a way to use an old B&W 4 inch portable TV with the RPi's S-video output. Then I was able to choose a suitable 800x600 mode in config.txt and everything worked.

I imagine CPC's converters would be better, or at least better documented. I usually am generous with EBay feedback, but was a bit miffed to be told the seller would pass on my comments to a technician, then hear no more from them.

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Windmill, TiltNot@Nonetel.com               Use  t m i l l 
J.R.R. Tolkien:-                                   @ O n e t e l . c o m 
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Windmill

or in the case of my network patch leads (new, out of the bag), being a tad too cheap and nasty to start with!

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Cheers, 

John. 
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John Rumm

Composite video, Baseband video, CVBS,

But not S-video or Y-C

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Graham. 

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Graham.

Oops. Sorry, I don't keep up properly on all the TV terminology. I meant the composite video output from the Pi. The football shaped B&W TV has, surprisingly, mono sound and composite video inputs, is analog only so useless nowadays for anything else, but allowed me to see that the Pi was in fact booting.

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Windmill, TiltNot@Nonetel.com               Use  t m i l l 
J.R.R. Tolkien:-                                   @ O n e t e l . c o m 
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Windmill

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