HDMI to VGA cable


8 posts
by superdexter » Fri Dec 21, 2012 2:41 pm
Hello everyone,

I am a new Raspberry Pi user, and I have a problem which I hope you can help me with.

I am trying to use my Pi with a flat screen monitor. The monitor only has an SVGA input, so I have connected it to the Pi with an HDMI to VGA cable, but the monitor does not seen to be getting an appropriate signal.

I should say that the Pi works fine HDMI to HDMI on TV.

I hope that someone can help me :).

Thanks!

Jack.
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by ski522 » Fri Dec 21, 2012 5:35 pm
You can't use just a cable that converts just the connector type to VGA. HDMI is a digital signal, while VGA is an analog signal, so you need a converter that will convert the digital HDMI signal into an analog VGA signal. Something like this would do the job http://www.meritline.com/hdmi-male-to-v ... 86032.aspx
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by superdexter » Fri Dec 21, 2012 5:40 pm
Thanks v much for that. Makes sense!

I wonder why they sell HDMI to VGA cables then...??

Cheers,

Jack.
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by Joe Schmoe » Fri Dec 21, 2012 6:18 pm
superdexter wrote:Thanks v much for that. Makes sense!

I wonder why they sell HDMI to VGA cables then...??

Cheers,

Jack.


The reason is that *sometime* it works. Specifically, it works if the HDMI source also generates an analog signal (along with the digital signal). I think they call it "DVI-A" (along with "DVI-D")
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by mahjongg » Wed Dec 26, 2012 8:56 pm
not HDMI to VGA , there is no way to put analog signals on the purely digital HDMI port, but there are DVI ports on monitors that also accept VGA signals because some monitor cards put the VGA signals they have anyway on some pins of the DVI port, that is called DVI-A which is short for "digital video interface - analog" LOL.
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by onkzzz » Wed Dec 26, 2012 9:26 pm
mahjongg wrote:not HDMI to VGA , there is no way to put analog signals on the purely digital HDMI port, but there are DVI ports on monitors that also accept VGA signals because some monitor cards put the VGA signals they have anyway on some pins of the DVI port, that is called DVI-A which is short for "digital video interface - analog" LOL.


well said... ive got a dvi-a on my tv but as i use hdmi to vga.. i get constant flickers from my pc. :cry:
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by johnbeetem » Thu Dec 27, 2012 2:14 am
There's a lot of information on HDMI to VGA adapters, including success stories, warnings, configuration settings, and links at the RasPi Wiki.

http://elinux.org/RPi_Verified_Peripher ... rter_boxes

http://elinux.org/RPi_Screens#RGB_analog.2FVGA
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by DanielChai » Thu Jan 31, 2013 7:23 pm
Just share my experience here.

I bought this inexpensive $9.90 hmdi-vga adapter on ebay
http://www.ebay.com/itm/261140675865?ss ... 1439.l2649
and it arrived in one week. Before I bought it, I knew that I would probably have to solder a USB cable on the adapter and have an external powered USB hub to power the adapter, given that the adapter is so cheap.

But it turns out that the adapter only requires a 105mA current when outputting 1024x768 60Hz. I measured this by directly putting a multimeter across the D1 diode (which can handle 200mA I think). So I tried to plug the adapter directly into my Pi after I modify the /boot/config.txt file as below:
# Settings for Flatron VGA monitor
# 1024 * 768
# Force HDMI signal even if monitor not detected
hdmi_drive=2
hdmi_group=2
hdmi_mode=16
hdmi_force_hotplug=1
disable_overscan=1

(Thanks to raspberry pi@http://www.amazon.co.uk/gp/pdp/profile/AB70B697XWPFR/ref=cm_cr_rdp_pdp)

The Pi works perfectly fine and my vga monitor gives a very sharp and clear display flawlessly.

I do realize that if I overclock the Pi to 1GHz or up and run quake3 the Pi will reboot because it drains too much power. But if I set the overclock to 900MHz or lower, the Pi runs quake3 perfectly with the adapter on.

I am not sure how much current the adapter will drain if outputting a higher resolution. But for 1024x768 or lower, I can be sure that this adapter is amazing.

The monitor I used is an old ASUS 15" laptop lcd screen plus a cheap LVDS-VGA driver board bought on ebay.
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