Point3Forever
Posts: 35
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Re: Low cost monitor

Sat Dec 03, 2011 5:57 am

Nice review Eclipse. I got for the 3.5" screen because it was the only one easily available to me. I had similar results. They can be powered from 8v-15v iirc. I picked up a power supply for $5 and the display cost about $22. I wasn't able to test it out very well, the only thing handy I had was a Wii. I was surprised by the quality for the cost of it. No noticeable ghosting, acceptable colour for NTSC.

I'm happy with it. I just need to find/make a touch panel for it :)

netomx
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Re: Low cost monitor

Sat Dec 03, 2011 6:17 am

Wow, thanks for that. I was in doubt to buy that monitor, but now I will. Thanks!!

nALLITeT
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Re: Low cost monitor

Sat Dec 03, 2011 11:12 am

Good review, Eclipse.
Can you disassemble that screen, so we will know what LCD interface it has?
If its lvds, we can try to replace cheap LCD screen with much better ( from laptop ).

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glenn66
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Re: Low cost monitor

Mon Dec 05, 2011 12:48 am

Eclipse, can I pick your brains? I've been working on something similar as a DIN-size touchscreen for a car engine management system and have a handful of 6.5" and 7" composite monitors in play, all remnants of in-car DVD systems where the DVD player died leaving orphan displays. Added to one of these is a 7" touch panel and USB interface which (along with 'xinput_calibrator') gives a simple to use touchscreen.

Are there any tips for getting a composite signal out of a laptop when running Linux? I can do this with Damn Small, but not Tiny Core, which I'd prefer to use. I have an old Compaq M500 I'm going to gut down to the mainboard and would like to use the composite output from this.

Connected to this, any tips on dropping the screen resolution to say 400 x 300 or something? On composite monitors using touch this seems to work best. Even 640 x 480 can be hard to read due to the lack of sharpness.

The best distro I've tried for this so far has been Linpus which came bundled with the first Acer netbooks and is optimised for small screens (7" and up), but is a bit too resource hungry for old PCs or a board computer like the RPi.

Thanks for any input.

Eclipse
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Re: Low cost monitor

Mon Dec 05, 2011 3:44 am

Quote from nALLITeT on December 3, 2011, 11:12
Can you disassemble that screen, so we will know what LCD interface it has?

I've taken a few photos of the innards of the display. The controller appears to be a MSTAR MST703-LF. There are two connectors on the board - a 4 pin (+12v, composite input 1, composite input 2, ground) connector for the external power and signal cables and a ZIF ribbon connector for the panel/backlight assembly.





Quote from glenn66 on December 5, 2011, 00:48
Are there any tips for getting a composite signal out of a laptop when running Linux?

Are you asking how to enable composite output under Linux, or can you already output a composite signal and just want tips for a clearer display?

If the former, it will depend on your video hardware. In the past, I've had graphics cards that:
• always output a composite signal displaying the contents of the primary framebuffer
• output a composite signal after being enabled using a manufacturer-supplied utility (usually Windows-based, but the hardware setting was permanent and persisted across reboots/shutdowns)
• as above, but the setting did not persist across reboots, requiring a Linux-based utility that could be added to the system's init script
• output the contents of a secondary framebuffer that could be accessed using X with the correct drivers

As for a clearer display, if you're using a text console, make sure you're not booting with any of the advanced framebuffer kernel parameters set, to ensure that you get a basic 80x25 character display rather than anything high resolution and fancy.

If you're using X, you might want to try a few of the following resolutions:
• 512x384
• 400x300
• 320x240
• 320x200

Even older hardware should support at least some of those. It's unlikely that a modern desktop environment will allow you to select resolutions that low though, so you may need to add the modes to your X config manually. Something else to look at would be the DPI parameter of the display, also in your X config, which will affect the scaling of text and graphic elements under DPI-aware X applications.

Liquid_chaos
Posts: 4
Joined: Wed Nov 09, 2011 4:32 pm

Re: Low cost monitor

Mon Dec 05, 2011 6:29 am

Dunno if anyone posted this already but

http://www.ebay.com/sch/i.html.....m270.l1313

50 dollars if you live in the US. Not sure about UK but k want one. Imm gonna make a wireless media center for $100

Kouri
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Re: Low cost monitor

Mon Dec 05, 2011 10:18 pm

You'd need to redo the wiring, but a Motorola Atrix lapdock provides you with a battery, screen, keyboard, trackpad and two usb ports for around $100. The dock portions provides an hdmi input as well as usb for the keyboard, trackpad, and hub. Oddly enough, it's set up to provide power through the keyboard usb, but that can probably be rewired into separate cables so you get one input USB and one power cable for the Pi.

http://www.wireless.att.com/ce.....bJxCDrHjox

http://www.wireless.att.com/ce.....bJxCDrHjox

linuxboi
Posts: 13
Joined: Sun Aug 28, 2011 11:12 pm

Re: Low cost monitor

Fri Dec 09, 2011 1:43 pm

I manged to get one of these off Ebay (ROADSTAR - LCD5014SIL ) for just £12, it has an AV input and the image is really clear. I'm yet to connect it to a Linux box to see how readable the text is:


http://uk.farnell.com/roadstar.....dp/7901178

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glenn66
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Re: Low cost monitor

Tue Dec 27, 2011 5:15 pm

First of all, many thanks (belatedly) to Eclipse for the advice with setting up X to run at lower resolutions.  I have manged to get a video signal out of a laptop mainboard using Damn Small and got the resolution to 400 x 300 which is ideal.  I'm looking at Linpus Linux as well because while it might have been pants for a netbook, the icon interface for a car computer would be ideal.

This is my 7" LCD touchscreen project, still on-going and targeted at the RaspberryPi since it has a composite output.

http://rgwni.blogspot.com/2011.....f-lcd.html

Am I right in thinking that there is an I2C touch panel chip?  That might be a neat way of getting the touch panel to talk with the R-Pi without USB.

I'm getting the 7" touch panels for under £5 a unit without the driver electronics.

Eclipse
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Re: Low cost monitor

Fri Dec 30, 2011 2:12 pm

This is unrelated to my earlier ramble on reversing monitors - I've come across a deal that may be of interest to those in the UK.

When walking past my local ASDA At Home store earlier, I noticed that they had a pile of 15" LCD TVs towards the front of the store. Unknown manufacturer of far eastern origin, 1366x768 panels, HDMI input, £50 each.

I didn't see one running so I have no idea about image quality or how they deal with overscan, and £50 is more than I'm willing to part with just to find out. Still, perhaps of interest to someone out there.

rwilliford
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Joined: Sat Dec 31, 2011 6:14 pm

Re: Low cost monitor

Sat Dec 31, 2011 9:06 pm

Forgive me if someone already mentioned this, but would there be a way to connect it via HDMI to a regular computer screen? Still new to this R-Pi stuff and would like to learn more about it still. But is this possible?

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johnbeetem
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Re: Low cost monitor

Sat Dec 31, 2011 9:25 pm

rwilliford said:


Forgive me if someone already mentioned this, but would there be a way to connect it via HDMI to a regular computer screen? Still new to this R-Pi stuff and would like to learn more about it still. But is this possible?


According to the wiki you can connect RasPi's HDMI output to a computer monitor that has an HDMI or DVI-D (digital) input.  You just need to get the correct cable.  You cannot connect RasPi to a VGA computer monitor without a rather expensive converter box.  An inexpensive DVI to VGA cable won't work: it uses DVI-A (analog) signals which are not present on RasPi's HDMI output.  The DVI-A signals are present on many PC graphics cards with DVI-I (integrated) connectors, which support both DVI-D and DVI-A.

richardamullens
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Re: Low cost monitor

Thu Jan 05, 2012 7:46 pm

Thanks for that information.  I had been wondering if a HDMI -> DVI -> VGA would work - seems not then.

I used to write in Macro-11 - great assembly language.

leds
Posts: 3
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Re: Low cost monitor

Thu Jan 05, 2012 10:59 pm

i was just looking at eclipse post and came across this on ebay

SteGriff
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Re: Low cost monitor

Mon Jun 04, 2012 8:39 pm

I have the same 4.3" screen as Eclipse, and have been trying it out with the Pi.
Interestingly, if you set framebuffer_width=480 and framebuffer_height=272, the screen doesn't fit properly. The picture is too wide and insufficiently tall.

Can we be sure that the native resolution of the screen is actually 480x272? The tech spec supplied with all the ebay entries reads:
Resolution: 1440(H) x RGB x 272(V)
...which is obviously wrong, because a horizontal resolution of 1440px would make this a super-retina display! I suspect that the prefixed 1 is a typo, and every seller has copied-and-pasted the info from each other.

Anyway, I just went to test my 440x272 theory and it turns out I've fried the screen with my experimentation. I think it was 320x240 which killed it. So, here:
Be careful when setting framebuffer sizes! You might fry your screen controller circuit!

Well, that's enough pi for today. This hobby is getting expensive.

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FalconXY
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Re: Low cost monitor

Wed Jun 06, 2012 10:50 pm

@ Eclipse
Thank you for the good review of the monitor. That helped a lot.

I was wondering what the 1440 pixels of the 4.3'' LCD displays are and if that's a false information.

I have googled it and have found out:

They are cheating of course. 1440 = 480*3 and the 3 stands for RGB. So each color pixel is calculated. :?

The 4.3'' LCD are 480x272 only.

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reiuyi
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Re: Low cost monitor

Sat Jul 14, 2012 3:18 pm

Asgo wrote:does anybody else feel strange when paying more for peripherals than for the computer itself?
Not that this should be understood as a suggestion to raise the price of the pi just for my comfort levels, but shopping for cables, input devices etc is just just a lot less fun if your only thought is:

"What the hell, this costs as much as the whole computer" ;)

I must say that my big screen, my headphone tube amp, AKG headphones, 1gbit lan router + switch, external NAS, studio monitors and my external soundcard/mixer also cost more than my computer when combined ;) (and I don't mean the raspberry)

It's not that strange when the peripherals cost more than the actual computer, especially if you're not going for the low-brand el-cheapo stuff. I mean to me it still makes no sense to buy a nice $1500 i7-based computer, only to connect it to a $100 screen and $25 speakers. I'm not saying you should immediately go for KRK speakers or Dell Ultrasharp screens, but man they add a whole new dimension to using a computer! You must balance quality out if you're going for quality. For goodness sake, otherwise it's like having a blasting fast Ferrari with a smelly cheap interior! Anyway this post wasn't aimed at Asgo

wmatkinson
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Re: Low cost monitor

Sat Aug 18, 2012 4:55 pm

Kouri - "You'd need to redo the wiring, but a Motorola Atrix lapdock provides you with a battery, screen, keyboard, trackpad and two usb ports for around $100. The dock portions provides an hdmi input as well..."

This sounds like a better starting point. I bought one of the low cost composite monitors. The resolution level is just too low for my end use of digital ham radio on the RPi. Kouri, have you had any luck with pushing HDMI through the In connector on the Motorola Atrix dock? If so, a custom RPi HDMI -> Dock cable might be an answer for many in this thread. If you have worked this out, please advise to the pin assignments on the ATRIX dock connector (not sure what connector type or proprietary?) for HDMI so we can try and hook up the RPi to this lapdock! Thanks.

DavidK
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Location: Kent, UK

Re: Low cost monitor

Wed Sep 26, 2012 6:56 pm

Hi everyone, I've just bought one of these little reversing monitors for my Pi. Of course I took it apart, and found it has the MST703-LF chip. When I googled it this thread was the 2nd result. The unpopulated 4-pin connector has one pin connected to a ground plane, one to somewhere in the power circuitry, and two straight to the chip. With the screen powered, the pin connected to the power circuitry is at 5V and the two pins connected to the chip are at 3.3V. USB, possibly?

(Edit: More clues to that, were the 12MHz crystal and the touchscreen pads on the flat ribbon cable)

jan741
Posts: 4
Joined: Sat Oct 13, 2012 9:04 pm

Re: Low cost monitor

Sat Oct 13, 2012 9:07 pm

hey, is it possible to use the screen of an old cell phone? and if, how can you do this. I want to buy an Raspberry and use it as an cheap and good "smartphone whitout special apps"

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