Using a Gert VGA 666 adapter - [HOWTO]


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by mahjongg » Sat Dec 20, 2014 6:50 pm
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If you have bought a Gert VGA 666 VGA adapter kit (available here, £6.00 at the time of writing), here are some instructions for how to assemble the kit, and how to configure Raspbian to use the adapter instead of its normal video output system.

For assembly instructions, see last page of the manual in GitHub. Make sure that you use the image below the words 'Through-hole side'. Alternatively, you can use the pictorial instructions on this site or this blog

When you have finished soldering the board, you can plug it in and power up your Pi. The adapter won't work immediately, so you will need an intermediate solution to get video. If possible, we recommend borrowing an HDMI or DVI-D monitor. If this is not possible, and you only have a composite TV or monitor (the sort with with a yellow RCA input), you can use that temporarily. You will, however, need a special TRRS (4-pole 3.5mm jack) cable for this (see the pictorial buying guide for more information). If you only have an RCA cable, you can temporarily connect the cable directly to the Pi by soldering the video wire (inner wire) to a PAD on the bottom of the Pi marked PP24. The shield of the RCA cable needs to be soldered to GND, and you can use nearby soldered PP6 for that. Please note, though, that this can be difficult, and and it can be easy to damage your Pi inadvertently. Soldering to the board will void your warranty so only try this if there is no other solution and you are very confident in your soldering skills.

However you manage it achieve it, when you are using composite video, you must "inform" NOOBS that you are doing so. Watch the ACT LED to see what happens when you boot NOOBS, and when booting seems to have finished, immediately press either the 3 key to get PAL (European ETC) or 4 key for NTSC (American) composite video. When you get video, DO NOT follow the instructions to make this permanent: if you do this, or the Pi will be locked into composite, and your VGA adapter might no longer work. If this does seem to have happened, hold shift during boot to get back into NOOBS, and press 1 to get back to HDMI video.

Now you have booted up, follow the instructions below to install the necessary drivers for the Gert VGA 666 adapter. You will need an ethernet connection for most of them: simply plug in the ethernet cable you normally use to get an internet connection, and Raspbian automatically will use it.

1. Add settings for the board to /boot/config.txt
Code: Select all
sudo nano /boot/config.txt

and add the following lines
Code: Select all
dtoverlay=vga666
enable_dpi_lcd=1
display_default_lcd=1

This will enable the board and make it the default display

2. You will have to disable the SPI and I2C interfaces, otherwise VGA666 will not function correctly. Use the Advanced options from raspi-config to disable SPI and I2C.
Code: Select all
sudo raspi-config


3 Reboot. If everything is working, then your Pi should come up with VGA resolution (640x480)

4 Now adjust the resolution for your monitor (see this post and this one for more information). For the VGA board use 'dpi_' instead of 'hdmi_'.
For example, you could add these lines to /boot/config.txt
Code: Select all
dpi_group=2
dpi_mode=35

This would be the equivalent of hdmi_group 2 (DMT), mode 35 (1280 x 1024 @ 60Hz)

Alternatively, try the following variations:

# For 1920x1080 60Hz (1080p)
Code: Select all
dpi_group=2
dpi_mode=82

or

# For 1024x768 60Hz
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dpi_group=2
dpi_mode=16


or

# For 800x600 60Hz
Code: Select all
dpi_group=2
dpi_mode=9


Thanks to DirkS for the original writeup.

P.S. This topic may have further information, such as which GPIO pins you can still use

[Edited seven times, latest edit 8 January 2016.]
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by thekeywordgeek » Sat Dec 27, 2014 12:41 pm
Thanks for this, I've built my GertVGA adaptor and it works!

Except, it drives the VGA monitor for most of the boot process then stops driving it and the screen goes blank before reaching the login prompt.

This happens whatever my dpi_group and dpi_mode settings are, or even if they aren't set at all

To ensure I haven't set a mode that won't work in testing I've used these values which should give me 640x480@60hz which I'd expect any VGA monitor to be able to support
Code: Select all
dpi_group=2
dpi_mode=4


Sadly it all goes dark too fast for me to see at what point in the boot process it stops working, I'm guessing that since I see something of the boot the driver software is working and my hardware is all OK, so something else is either making it go into an incompatible video mode or disabling the VGA output.

Has anyone any suggestions?
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by DirkS » Sat Dec 27, 2014 12:56 pm
Maybe some hdmi setting interfering?
Can you post the output of
Code: Select all
vcgencmd get_config int


Gr.
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by thekeywordgeek » Sat Dec 27, 2014 5:08 pm
Here as requested:
Code: Select all
pi@raspberrypi ~ $ vcgencmd get_config int
disable_overscan=1
program_serial_random=1
config_hdmi_boost=2
emmc_pll_core=1
hdmi_force_cec_address=65535
display_default_lcd=1
enable_dpi_lcd=1
dpi_mode=4
dpi_group=2
framebuffer_ignore_alpha=1
framebuffer_swap=1
disable_splash=1
safe_mode_gpio=1
temp_limit=85
force_pwm_open=1
pause_burst_frames=1
second_boot=1
avoid_fix_ts=1
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by DirkS » Sat Dec 27, 2014 5:57 pm
That looks ok to me.
I just remember that I had the same problem when I forgot to blacklist i2c and spi.
Going back over my instructions... another error.

Blacklist needs to be with underscores instead of dashes.
Code: Select all
blacklist spi_bcm2708
blacklist i2c_bcm2708


And I thought I had tested it all... :roll:

Gr.
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by mahjongg » Sat Dec 27, 2014 6:14 pm
DirkS wrote:That looks ok to me.
I just remember that I had the same problem when I forgot to blacklist i2c and spi.
Going back over my instructions... another error.

Blacklist needs to be with underscores instead of dashes.
Code: Select all
blacklist spi_bcm2708
blacklist i2c_bcm2708


And I thought I had tested it all... :roll:

Gr.
Dirk.
Solved that one too.
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by thekeywordgeek » Sun Dec 28, 2014 11:57 am
Edited with underscores: no luck sadly.

Have trawled through everything I can think of on this SD card, removed the only thing I could think might cause an issue (simbamond, for the pi.gate.ac.uk battery power unit), but still no luck. Otherwise this one's pretty stock.

Will keep at it. At least my few seconds of activity at boot tell me it works.
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by DirkS » Sun Dec 28, 2014 1:05 pm
thekeywordgeek wrote:Edited with underscores: no luck sadly.

Have trawled through everything I can think of on this SD card, removed the only thing I could think might cause an issue (simbamond, for the pi.gate.ac.uk battery power unit), but still no luck. Otherwise this one's pretty stock.

Will keep at it. At least my few seconds of activity at boot tell me it works.

Do you see spi-bcm2708 and / or i2c-bcm2708 in the list with loaded modules (use 'lsmod').

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by thekeywordgeek » Mon Dec 29, 2014 3:28 pm
i2c_bcm2708 is there, yes. And another look at the blacklist file confirms I have it there exactly as it appears, no typos. Curiouser and curiouser.

Edit: I notice /etc/modprobe.d/raspi-blacklist.conf also tries to block the i2c and spi modules, though it does so with the hyphen rather than the underscore.

Code: Select all
pi@raspberrypi ~ $ lsmod
Module                  Size  Used by
snd_soc_wm8804          7932  0
snd_soc_tas5713         5573  0
snd_soc_pcm512x         9034  0
i2c_bcm2708             4943  0
i2c_dev                 5769  0
snd_bcm2835            19496  0
snd_soc_bcm2708_i2s     6210  0
regmap_mmio             2818  1 snd_soc_bcm2708_i2s
snd_soc_core          128465  4 snd_soc_pcm512x,snd_soc_wm8804,snd_soc_tas5713,snd_soc_bcm2708_i2s
snd_compress            8259  1 snd_soc_core
regmap_i2c              1661  4 snd_soc_pcm512x,snd_soc_wm8804,snd_soc_core,snd_soc_tas5713
snd_pcm_dmaengine       5505  1 snd_soc_core
regmap_spi              1913  3 snd_soc_pcm512x,snd_soc_wm8804,snd_soc_core
snd_pcm                83845  3 snd_bcm2835,snd_soc_core,snd_pcm_dmaengine
snd_page_alloc          5132  1 snd_pcm
snd_seq                55484  0
snd_seq_device          6469  1 snd_seq
snd_timer              20998  2 snd_pcm,snd_seq
leds_gpio               2079  0
led_class               4118  1 leds_gpio
snd                    62252  7 snd_bcm2835,snd_soc_core,snd_timer,snd_pcm,snd_seq,snd_seq_device,snd_compress
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by thekeywordgeek » Mon Dec 29, 2014 3:58 pm
OK, I've fixed my problem with the i2c_bcm2708 module loading, with the help of this page:
https://wiki.debian.org/KernelModuleBlacklisting

I did a blacklist with a fake install as instructed:
As example to disable modulename using fake install you have to:
Create a file '/etc/modprobe.d/<modulename>.conf' containing 'install <modulename> /bin/true'.
Reboot.

So I sudo created a file in /etc/modprobe.d called i2c_bcm2708.conf containing the following line:
Code: Select all
install i2c_bcm2708 /bin/true

And now I have a VGA monitor displaying the login prompt.
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by mahjongg » Mon Dec 29, 2014 6:23 pm
I don't immediately understand what the implications are for the howto. Anything I should append or change?
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by thekeywordgeek » Tue Dec 30, 2014 12:26 am
I was hoping someone would come along and explain exactly what the thing I did actually does, and thus whether it's a more general HOWTO thing or just something weird about my setup.

Has anyone else made it work using just the HOWTO?
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by DirkS » Tue Dec 30, 2014 12:41 am
thekeywordgeek wrote:I was hoping someone would come along and explain exactly what the thing I did actually does, and thus whether it's a more general HOWTO thing or just something weird about my setup.

Has anyone else made it work using just the HOWTO?

Yes, me. And I know of at least one other.
I have not yet heard of anyone else *not* being able to do i the *normal* way.
Do you use Raspbian with the standard kernel?
Can you post the output of 'uname -a'

Gr.
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by thekeywordgeek » Tue Dec 30, 2014 12:43 pm
Absolutely stock Raspbian, and constantly kept up to date with apt-get. It's been used for a few things, Python tinkering, the camera module, and the aforementioned battery PSU board. But other than that no kernel tinkering.

Sadly I'm not on the same network as the Pi in question at the moment so I can't deliver any output from it. But I doubt it'll give anything unusual.

I guess the method of killing the i2C module that I found is the kind if thing that would be a "useful to know if you have that problem" kind of thing rather than a "Must be in the HOWTO" thing.
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by DirkS » Tue Dec 30, 2014 6:49 pm
thekeywordgeek wrote:I guess the method of killing the i2C module that I found is the kind if thing that would be a "useful to know if you have that problem" kind of thing rather than a "Must be in the HOWTO" thing.

Yes, agree with that.
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by chuewailian » Thu Jan 01, 2015 12:25 pm
For our case, it was not necessary to blacklist spi & i2c (as per original Gert's pdf manual).

Verified & loop-tested on both RPi Model B+ and A+.

Our quick start guide (with screenshots) @:
http://blog.queststem.com/post/10430765 ... dapter-666
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by mancity » Fri Jan 02, 2015 4:19 pm
Hi,

Just received one of these today. I presume all of the resistors are NOT the same and I have to use the exact ones in the correct holes?

Is there a guide which actually help with this at all as I cannot even see the colours :shock:
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by rpdom » Fri Jan 02, 2015 5:08 pm
mancity wrote:Hi,

Just received one of these today. I presume all of the resistors are NOT the same and I have to use the exact ones in the correct holes?

Is there a guide which actually help with this at all as I cannot even see the colours :shock:

The link given in the top post has details of the resistors. The colours are important. I agree that they can be difficult to read (which I why I prefer surface-mount with numbers on that I can read with a magnifying glass).

If you have access to a multimeter you can use that to measure the resistance to work out which is which.
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by PiGraham » Fri Jan 02, 2015 5:10 pm
Any news on software / firmware to support dual display (HDMI + VGA)?
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by mancity » Fri Jan 02, 2015 5:50 pm
I might as well throw mine in the bin.
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by BMS Doug » Fri Jan 02, 2015 9:12 pm
mancity wrote:I might as well throw mine in the bin.


As rpdom said a multimeter will tell you the resistances (it's what I used as I couldn't make out the colours). The guide to which resistor goes where is linked in the first post of this thread. (https://github.com/fenlogic/vga666/tree/master/documents)



Don't throw it in the bin, if all else fails you can mail it to me with a self addressed stamped envelope enclosed and I'll solder it for you. Don't skimp on the postage, I'm not going to pay for the privelidge of assembling it for you.
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by mancity » Fri Jan 02, 2015 9:49 pm
BMS Doug wrote:
mancity wrote:I might as well throw mine in the bin.


As rpdom said a multimeter will tell you the resistances (it's what I used as I couldn't make out the colours). The guide to which resistor goes where is linked in the first post of this thread. (https://github.com/fenlogic/vga666/tree/master/documents)



Don't throw it in the bin, if all else fails you can mail it to me with a self addressed stamped envelope enclosed and I'll solder it for you. Don't skimp on the postage, I'm not going to pay for the privelidge of assembling it for you.


Is that a serious offer?

I'd want to pay you to assemble it as well as p&p.
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by BMS Doug » Fri Jan 02, 2015 10:46 pm
mancity wrote:Is that a serious offer?

I'd want to pay you to assemble it as well as p&p.


You wouldn't want to pay my hourly rate, better to just send it and let me solder it for the fun of it.

Here's a pic of my one (assembled)
Image
I'll send you a pm with contact details.
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by FTrevorGowen » Sun Jan 11, 2015 8:51 pm
FWIW folks, I've posted a series of "assembly steps/photo's" within my webpages here:
http://www.cpmspectrepi.webspace.virgin ... apter.html
(I've yet to perform either B+ or A+ "case mods", or use a bare-board to test it etc. )
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by mancity » Sun Jan 18, 2015 4:34 pm
When I do this bit -

wget https://raw.githubusercontent.com/fenlo ... ob-dpi.bin
sudo mv dt-blob-dpi.bin /boot/dt-blob.bin

I get a 'not permitted' error on the second part regarding the /boot/dt-blob.bin?

Can anybody help please?

I tried to carry on anyway and when I reboot, the screen comes on initially in low res and looks like it'll work, then goes black :? .
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