pecmac
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Using a VGA monitor on R_Pi

Sat Jan 19, 2013 8:49 pm

Hi
I just received a Raspberry-pi as a gift.

I don't have a TV or a spare HDMI monitor just a VGA monitor.
So I have bought a "Pi-View" HDMI to VGA converter from element 14. However It doesn't work it I get a bleary moving fragmented colours on the monitor nothing that is readable.
The Raspberry pi appears to be working ok.
The Pi-View when I plug it in to another computers HDMI source seems to be work ok.
It doesn't work as described when plugged into the pi.

Any one got any suggestions how to make this work ??

Cheers
pecmac

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mahjongg
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Re: Using a VGA monitor on R_Pi

Sat Jan 19, 2013 11:04 pm


Mobius
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Re: Using a VGA monitor on R_Pi

Sun Jan 20, 2013 12:23 am

Hopefully you got a real HDMI to VGA converter and not just an adapter cable. Usually the converters look like this:

http://www.ebay.com/itm/New-Chipset-HDM ... 3a7d9892d6

You will need to edit your "/boot/config.txt" file to force the HDMI output to turn on. Otherwise the Pi will not detect an HDMI connection and the video will come out the composite port. To start, just uncomment this line: hdmi_safe=1

That will force the HDMI on and set the video resolution to 640x480. After that works, you can read up on which commands to edit to provide your desired resolution. These are the three I use with my HDMI to VGA adapter and it works on either my TV or my VGA monitor (1366x768). Your resolution may be different.

Code: Select all

framebuffer_width=1366
framebuffer_height=768
hdmi_force_hotplug=1

pecmac
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Re: Using a VGA monitor on R_Pi

Sun Feb 24, 2013 3:40 pm

Thanks for the reply. Not had much time recently to fiddle.

I will read the info........ Have been trying to edit the Config file but can not read the SD card by my Apple computer I thought that because the Config file is a txt I would be able to modify it using any computer with a card reader? May be I am over looking some thing obvious!

Thanks for your reply appreciated.
pecmac

pecmac
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Re: Using a VGA monitor on R_Pi

Sun Feb 24, 2013 3:48 pm

Thanks for the in put!
I have not had time recently to play with it.
My converter looks just the same as the one in the link, it was expensive! Thinking of returning it as it is of no use so far!
I was trying to get at the Config.txt file by using another computer and a card reader but it doesn't see the card. I thought that because it was a .txt file I would be able to edit it on any computer? May be I am showing my ignorance or over looking some thing obvious?? I guess we all have to start some where.

Thanks for the help all the best
Pecmac
Mobius wrote:Hopefully you got a real HDMI to VGA converter and not just an adapter cable. Usually the converters look like this:

http://www.ebay.com/itm/New-Chipset-HDM ... 3a7d9892d6

You will need to edit your "/boot/config.txt" file to force the HDMI output to turn on. Otherwise the Pi will not detect an HDMI connection and the video will come out the composite port. To start, just uncomment this line: hdmi_safe=1

That will force the HDMI on and set the video resolution to 640x480. After that works, you can read up on which commands to edit to provide your desired resolution. These are the three I use with my HDMI to VGA adapter and it works on either my TV or my VGA monitor (1366x768). Your resolution may be different.

Code: Select all

framebuffer_width=1366
framebuffer_height=768
hdmi_force_hotplug=1

drgeoff
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Re: Using a VGA monitor on R_Pi

Sun Feb 24, 2013 5:19 pm

Yes you should be able to see and edit the config.txt file on another computer.

What is the evidence for your earlier remark that the RPi appears to be working OK?
Quis custodiet ipsos custodes?

pecmac
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Re: Using a VGA monitor on R_Pi

Sun Feb 24, 2013 7:52 pm

I don't seem to be able to see the SD card on another computer I was wondering if the formatting or the fact that it is an OS disk is the problem?

The RPi is working okay as when I plug it into an HDMI monitor it appears as it should. My reason for wanting to use a VGA monitor is that is what I have spare at the moment, I don't have a TV old or new to try it out with.
drgeoff wrote:Yes you should be able to see and edit the config.txt file on another computer.

What is the evidence for your earlier remark that the RPi appears to be working OK?

Tony61
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Re: Using a VGA monitor on R_Pi

Thu May 09, 2013 7:58 pm

What was the end result to all this as I am having similar problems and was thinking of getting a Pi-view!

Nkiki2000
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Re: Using a VGA monitor on R_Pi

Wed Jul 30, 2014 4:40 pm

To acess the pi's files from a different computer you'll need to look for it In the disk settings. That's because linux uses a different partition format. :?:

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mahjongg
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Re: Using a VGA monitor on R_Pi

Wed Jul 30, 2014 7:48 pm

Tony61 wrote:What was the end result to all this as I am having similar problems and was thinking of getting a Pi-view!
Shamelessly copied from another thread for your convenience:
Normally a PI can detect which resolutions the monitor supports, because the monitor contains a small I2C memory chip that has this information. The PI can then adjust its resolution and sends an optimal signal for the monitor that it is connected to.

This memory chip needs a little bit of current at 5V to work, and so the HDMI standard prescribes that 5V should be provided, and as much as 50mA, (most memory chips use 15mA).
many cheap HDMI to VGA don't have their own power supplies, and "steal" the power meant for the memory chip, and the cheaper ones also use at least 200mA. To get enough current they simply do not connect through the 5V for the EEPROM, and may also not connect the I2C signals to talk to the memory chip (which by the way is also contained in modern VGA monitors, not just HDMI and DVI-D monitors). more expensive adapters, have a separate power input, and therefore do normally route power, and I2C control signals, through to the VGA monitor.

that is while using some adapters the PI can still "see" the memory chip, and with other adapters it cannot.
in such cases the resolution must be manually set using config.txt.

Of course the PI still will emit a default resolution, and perhaps that happens to be supported by your VGA monitor, in which case it would appear to "just work", but in fact you were just lucky that that happened, and the resolution might still not be optimal for your monitor.

the old B could only deliver a maximum of 200mA through a diode, (4 times the prescribed amount) and drawing more could even damage the diode, and the diode also caused some drop in the 5V to the adapter, thats why "hdmi powered" adapters were not recommended, although you mileage may have varied.

on the new B+ there is now an over-current protection IC that safely limits the HDMI power current to 400mA.



My recommendation, always use an adapter that routes through the 5V and I2C signals, so you won't need config.txt.
also the buying guide is a good read: http://www.raspberrypi.org/forums/viewt ... =63&t=4277

W. H. Heydt
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Re: Using a VGA monitor on R_Pi

Wed Jul 30, 2014 9:21 pm

One other thing to consider on the whole "VGA and the Pi" issue. If you hit your local thrift shops or equivalent (or Freecycle groups if you're into that), you can probably get a suitable monitor with DVI-D input for less than an HDMI-to-VGA converter, or least less than a decent one. My "prize" acquisitions through a local thrift shop, for instance, are a Viewsonic 912b (19" 1280x1024 with speakers) and a pair of Dell pro-grade 1905FPs (same specs, but no speakers) and none of the three cost me over $20 by the time a Pi was displaying on them.

If you have the right contacts, you may be able to find a company that is replacing desktop systems and get monitors for free, as giving them to you will save the company the electronics recycling fees.

At the extreme end, I know someone who got a 27" 1920x1024 monitor through Freecycle at no cost.

The monitors are out there...save yourself the cost of a converter.

rfrazier
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Re: Using a VGA monitor on R_Pi

Thu Jul 31, 2014 5:49 am

Hi Pecmac,

I've been doing research on this very issue. You might find this interesting. The products described here might work without any tweaking.

I've been thinking some more about options to connect small screens to the pi.

I'm thinking of options which don't use gpio.

One option is a composite display. These have been discussed a good bit, and include things such as backup camera monitors. They can be very inexpensive, but also only usually (not always) have only 240 lines of resolution. So, the output may appear fuzzy with text, etc.

Then, there are small hdmi monitors, which tend to have very good quality but very high prices, some prices even more than 22" monitors.

It occurred to me that I might be able to find a middle ground, with good quality and medium pricing, by searching for 7" vga monitors (for example). It appears my theory may be correct.

Caveat, I haven't tested any of these products. This is just research at this point. I cannot guarantee everything will work together.

I found this 7" monitor which looks promising:

http://www.amazon.com/Monitor-Computer- ... B00I2K45X8

It has 1 vga input, 2 composite video inputs, and a sensing wire for your reverse lights if in a car with a backup camera. It also has 480 lines of resolution. All for $ 43. Of course, if this isn't in a car, you have to provide a separate 12v power supply.

This should make a pretty good monitor for the pi. You could drive it from the composite output, since the standard resolution for composite (in the USA) is 480 lines. However, you'd probably get better quality by using the VGA input.

So, the next problem is getting vga out of the pi. I've read many accounts of people having problems with that. But, I've read many others who are having it work very well. You just have to do it right.

Here are two hdmi to vga adapters on amazon made by cable matters. Each has a port for an external usb power source, and includes the usb cable. The reviews on the 1st one are overwhelmingly positive. The 2nd one should be similar since it's the same company. The 1st does not support audio. The 2nd does.

http://www.amazon.com/Cable-Matters-Gol ... B00879DM56
for $ 16

http://www.amazon.com/Cable-Matters-Act ... B008O7RH5C
for $ 22

If you access each review page and use your browser's find function (ctrl-f on firefox) and search for raspberry, you will find many people using these things with raspberry pi's. Many of them don't put the word raspberry in the subject line, which is why you have to search for it.

Some report failure with the pi, or failure in general. I think many of these are operator error. With this product, you MUST attach it to an external power source, using the micro usb port and usb cable provided (or another cable). Plug the micro end into the port on the adapter and the regular end into a usb power source NOT ON THE PI BOARD. Depending on how much power your pi and it's accessories are drawing, you may need a separate usb port not associated with the pi at all, such as a 2nd usb power adapter or a nearby pc usb port. As far as I can tell, if you power this thing properly, and don't deprive the pi of power, everything should work fine. Remember, with the pi b+ and a 2a power supply, you can only draw about .3a from each of the usb ports on the board, so the pi's power supply may not be up to the task of running the pi, it's accessories, and the screen, even if you plug the screen directly into the power supply.

After getting all my original pi parts, plus books and such, I don't have a budget to order this screen, it's power supply, and the active hdmi adapter right now. But, I'm considering it for later. For now, I might just get the adapter and try tying the pi into my vga kvm switcher along with my normal keyboard, mouse, and monitor.

You might also find this thread, and the ones it links to useful:

http://www.raspberrypi.org/forums/viewt ... 38&t=83030

I thought I'd pass the info along. If any of you have used these or other hdmi to vga adapters, it would be interesting to know how it worked out. It would also be interesting to know how to switch from hdmi with audio embedded versus hdmi with separate audio from the other jack on the pi.

Sincerely,

Ron
(PS - If you email me and don't get a quick response, you might want to send again after a couple of weeks. I don't always see new email messages quickly.)
Ron's Tech Rant Blog: techstarship.com - Blog RSS: techstarship.com/feed/
Ron Frazier

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