ExcellentBreakfast
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Joined: Mon Aug 26, 2013 9:15 pm

HDMI to VGA Adaptor Help!!

Mon Aug 26, 2013 10:35 pm

Hi and thanks for reading,

Having bought a Type-B Raspberry Pi board within the first few waves of shipping last year, I was disappointed to find that it only supported HDMI, having no devices/screens in the house which support it. VGA is ideal, but I didn't actually go out and get a converter until a couple of weeks ago (I had only used it once since purchasing - using my friend's TV, ie. with HDMI). Online guides and articles within forums had told me that it wasn't as simple as simply plugging it in, you had to also mess with a certain 'config.txt' on the SD card containing the OS, which I was prepared to do.

Now I am using the Raspberry Pi on the TV in the holiday house I am staying in, and have struggled for hours trying to get any success on the VGA monitor I have brought with me.

The Raspberry Pi boots with no problems and I cannot see any situation where the system has had any trouble with any of its features. I am using a 4GB SDHC card from RS Components, pre-installed with what the sticker calls 'Raspberry Pi OS' but what I have researched is probably Debian (6, I think). Unfortunately, there is no such 'config.txt' anywhere on the card and so I have created one in /boot using sudo touch on the command prompt (as per the advice of some internet wikis) and adding these lines to the empty file, which I found:

hdmi_force_hotplug=1
hdmi_group=2
hdmi_mode=36
hdmi_drive=2

I moved the output to my monitor, using the adaptor, but nothing showed, besides turning off its no-output-self-test-colour-whatever-screen and displaying a black screen. I must have messed up the settings, I thought, and now it probably won't display on the TV either! Actually, it was fine back on the HDMI TV, so I assumed the settings weren't correct for changing it.

After adding/removing several other commands, changing the order of the settings in the file, etc. I turned to my adaptor, having seen that only some such devices will function with the Pi, and tracked it back to the eBay page here --> http://www.ebay.co.uk/itm/251261699944? ... 1439.l2649

As you can see, the bottom of the page shows a footnote concerning the Raspberry Pi, with specific settings, and some clue that this is one such functioning adaptor. Those settings didn't work either.

Anyway, to finish off with the question I am asking: Where does the fault lie and what should I do next? It has occured to me that the system might be ignoring 'config.txt', as it has so far made zero changes, but no internet solutions to it doing this have been any help. As my last port of call, I signed up to this forum and eagerly await any responses. Thanks for reading such a long question but this is really stressing me out!

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mahjongg
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Re: HDMI to VGA Adaptor Help!!

Tue Aug 27, 2013 12:09 pm

The "raspberry PI OS" on the card might be quite old, I would wipe the card with the formatter as described in Downloads, (menu in this page) then install NOOBS, and try again.

Yes, not all HDMI to VGA converters without external power will work, as the PI wasn't designed to work with them. Some will simply want to draw too much power, (older designs) it also depends on your power supply. But I would discourage using HDI powered adapters, buy only those with external power input.

P.S. yes, on older versions of raspbian the config.txt file could be missing, but can be installed manually.

huckfh
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Joined: Tue Aug 27, 2013 4:33 pm

Need help with the RPi Hdmi to Vga adapter Pi-view

Tue Aug 27, 2013 4:35 pm

I just received today my first RPi and it works fine as far as i can see, but since i'm using a monitor with a vga connector i bought also this adapter:

https://www.modmypi.com/pi-vew-raspberr ... name=vga[1]

that is presented as the "Official" one, but i'm kinda disappointed cause after spending almost 30 euro for this, it doesn't work properly and my screen is constantly blinking randomly, i read around about it, and i tried editing the config.txt many times, almost tried everything at this point i guess, but without any good results. From what i discovered lurking around on some forums, it's cause the adapter it drains too much power, i bought this psu:

https://www.modmypi.com/shop/raspberry- ... upply-eu[2]

i thought it was enough power considered that this site sells all the stuff supposedly tested on the RPi.

Now i'm still waiting for my Hub, should be arrive tomorrow bought it from amazon:

http://www.amazon.it/gp/product/B002YCI ... F8&psc=1[3]

from the official site of this Hub it said that the psu is 3.5a , now i'm probably going to ask a noob question, are there any chances that if connect mouse and keyboard to this hub and power the rpi through it there will be enough power for everything?

http://www.delock.com/produkte/G_87467/ ... e/4.html[4]

drgeoff
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Re: Need help with the RPi Hdmi to Vga adapter Pi-view

Wed Aug 28, 2013 7:45 am

3.5 amps is enough to power RPi, keyboard, mouse, hub, HDMI to VGA converter and lots more. :)

PSUs don't always live up to the claims made for them. :( But from the look of that one I'd be reasonably confident that it won't be far off its spec.

Don't know if inadequate power is the reason for your display problem. You'll soon know.

itimpi
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Re: Need help with the RPi Hdmi to Vga adapter Pi-view

Wed Aug 28, 2013 11:56 am

The power that I supplied to the HDMI port is very limited (I think something around 100mA) regardless of your power supply. This can mean that there are issues with HDMI->VGA adapters that are not externally powered. (as appears to be the case with the one you mentioned). Having said that there are plenty of reports of people successfully running converters that take their power from the Pi - but there are also lots of reports of failures.

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mahjongg
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Re: Need help with the RPi Hdmi to Vga adapter Pi-view

Wed Aug 28, 2013 12:02 pm

There is no "official HDMI=>VGA adapter" as far as the RPF is concerned. Such claims are fully baseless.

Even more any non externally powered adapter at this point seems to be a bad choice (that is, unless one comes on the market that manages to use less than 0.2A) !
Unfortunately the sellers of these devices are always silent about it's current consumption!

This one seems to be the "neweer" adapter that seems to work for some, but not in all cases. It was one of the fist cheap devices that some people bought for the PI, but "your mileage may vary". It seems it can use as much as 0.4A under some circumstances!

see http://elinux.org/RPi_VerifiedPeriphera ... y_adapters

Increasing the power supply's output current will only partially help, as the biggest problem is that all the current to the adapter must flow through a diode (D1) rated at 0.2A ! Also the polyfuse on the PI (F3) will prevent currents larger than about 1A flowing into/through the PI. But if you feed the PI through the normal USB port on the back, that has no consequence as you are actually bypassing this fuse (so be careful, as there is no protection against shorts and over-voltages if you do!).

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