Monitors for Beagleboard
David R. Lane (77) 766 posts |
What makes and models of monitors do folk recommend for the Beagleboard? I know the type of monitor from the hardware documentation pages, but would like a recommendation. It would be good to know whether the recommendation would be also suitable for a desk top computer including the Iyonix PC. I have joined the ranks and bought a BB. |
Dave Higton (281) 668 posts |
Makes and models are rapidly moving targets, so any specific response might well be out of date before it’s any use to anyone. (I bought a Xerox monitor, but by the time I’d got it and tried it out, it was no longer available.) The BB can’t produce a high pixel rate, so there is no point in buying a monitor with an enormous number of pixels unless it can either (1) accept a lower resolution input and display it acceptably, or (2) accept a low refresh rate. As an example, you can get 1280×1024 x 54 Hz. Note that the pixel rate does NOT depend on the colour depth, unlike what we’re used to with RISC OS. You will need a monitor with a DVI-I, DVI-D or just DVI (if it is specified to have a digital input) or HDMI for the BB, and if you want it to have an analogue input, that’s either DVI-I, DVI (if it’s specified to have an analogue input) or VGA. By way of a little explanation: DVI-I is Integrated (analogue and digital), i.e. supports both. The term DVI is used too loosely in my opinion, which makes buying these things worrying. DVI-D is digital only, DVI-A is analogue only. If you’re buying DVI adaptors and/or cables, please bear in mind that not all combinations of DVI plug and socket can be mated. Also bear in mind that some monitors come with a captive cable which ends in a plug; some don’t, so have a socket. You may find the paragraph in How to get started with a BeagleBoard useful. |
Trevor Johnson (329) 1645 posts |
There are some home made projects around and also one commercially available VGA daugtherboard IIRC. VGA adapters are available but costly (and possibly give an inferior picture although that’s an assumption). The monitor I have accepts both DVI-D and VGA. However, the auto-detection doesn’t seem to function when both cables are plugged in. You might want to ask a question about this before you purchase such a dual-input monitor. |
Dave Higton (281) 668 posts |
One aspect of a monitor driven digitally at is native resolution is that the mapping of video-driver pixels to screen pixels is perfect. The consequence is that all the one-pixel-wide vertical lines look crisper than you have ever seen in your life. Having tried DVI-D and enjoyed the results, I would advise everybody to forget any idea of extracting an analogue video signal from the BB in any way. Put your money into a monitor. They are available from about GBP100. Just my 2p worth. |
Jeffrey Lee (213) 6048 posts |
The main things to keep in mind are that if you buy an LCD, you’ll want to be using it at its native resolution. Any other resolution and the pixels will either be squashed or stretched and most likely look rather ugly (unless the image can scale exactly, e.g. a 800×600 image on a 1600×1200 monitor). A CRT is much better at displaying different resolutions of image, but they’re obviously bulkier, harder to find nowadays, and unlikely to give a better quality than a native-resolution LCD. Also bear in mind that because there’s no physical electron beam to move around, an LCD is able to use much lower porch & sync timings than a CRT, resulting in higher resolutions/frame rates for a given pixel clock. So an LCD is probably the safest bet if you want to get the highest possible resolutions out of the BeagleBoard. The choice of analogue or digital input signal probably won’t make any difference to a CRT, but for an LCD (running at its native resolution) a digital signal is always going to be the best. If you’re not running an LCD at its native resolution then I suspect the difference between analogue and digital won’t be noticeable, due to the already ugly scaling. 1280×1024x57Hz is a safe bet to aim for, but if you prefer widescreen monitors then 1440×1050x50Hz should also be doable if you can find a monitor that’s happy with 50Hz modes (you might be able to squeeze a slightly higher framerate out – I haven’t tried any 1440×1050 modes yet, so I’m not sure what the maximum would be) If you’ve got an HDTV then you could also try 1920×1080x30. Some monitors might support that mode as well, but unfortunately mine doesn’t, so I wouldn’t count on it if you decide to go for a big monitor (although 1920×1080x60 or 1920×1200x60 will obviously work great with the Iyonix, any PC made in the last 8 years or so, an upgraded RiscPC, and perhaps the A9home, although I’m not sure offhand what max resolution that’s capable of) |
David R. Lane (77) 766 posts |
I have seen details of an Iiyama ProLite B2206WS-1 which has a DVI-D connector with resolution 1680×1050 and vertical sync 55-75Hz. Is that likely to work with the BB? Is there a monitor definition file for it? The latest MDFs I have are dated around October/ November 2009 and haven’t seen anything more recent. |
James Peacock (318) 129 posts |
Can’t know for certain, but I use a ProLite E2607WS with a BeagleBoard 1680×1050 at 43Hz which is well below its advertised 55Hz minimum v-sync. It isn’t its native resolution but the monitor does a pretty good job with it. I’ve also got a mode file for the Iyonix, driving it up to 1920×1200 at 60Hz. If anyone fancies risking their monitor, I’ll put them up. |