Potential USB display

[jeroen94704]

Samsung has a range of photo-frames which (on windows) can double as a mini-monitor, of which I have the SPF-75H (7", 800x480). So far, I hadn't been able to find any info on Linux support for these frames, but today I stumbled across a site that had the necessary bits, and I managed to get the frame working and showing images from my Ubuntu box.

Now I think these displays would be great as high-quality wifi-radio displays. They're relatively cheap too (I paid EUR 40 for mine). I'm thinking about album art and a whole bunch of other stuff that could be shown on a high-res color display!

To get this working, I need to build the code for the Router platform. How hard is it to get a build-environment set up?

Jeroen

[mightyohm]

It's not too bad to compile the firmware like I did, using packages already available. There are instructions on openwrt.org to do this. Adding packages is more difficult, I have never found a very good source of documentation, it is sort of spread across the forums - but I have been able to successfully compile some simple programs.

I think I have seen the displays you are talking about - someone used one to add a TTY console to a 520gU or similar router. Very cool.

Sounds like you are working with some fun stuff. Good luck and keep us posted with your progress.

[LloydEwing]

Re: Looking for Larger Alphanumeric Display

If I ever get around to it, my plan is to use a photoframe as a full-color, hi-res display for my mpd box (which is based on a WL-500G router), showing things like album art etc.

Physically connecting a display isn't hard at all, since many of these frames can be used as secondary monitors through USB. So no fancy hardware hacking and/or soldering is necessary. The problem is driving the display. There are no drivers or anything available. For the Samsung photoframe I have, I need to draw everything manually in memory, encode it as a jpeg, and send that over the USB line. This isn't necessarily rocket-science either, but it IS a lot of work. Oh, and it remains to be seen if the routers we use have the CPU power to do all this at reasonable speeds, while playing music stutter-free.

Jeroen

(It seems like I should reply to the post above from "Re: Looking for Larger Alphanumeric Display" here, because this thread for the photo frame discussion already exists.)


Jeroen,
I would like to know more about what you want to do. Do you have links to related work that other people have done?

I wonder if my desire for an alphanumeric display on a photo frame would be a lot easier to implement. As Jeff described it above on Feb 27, you could say that what I want is just a display for a TTY console (with large characters).

You described the problem this way:

For the Samsung photoframe I have, I need to draw everything manually in memory, encode it as a jpeg, and send that over the USB line.

Are each of those items new programs that will have to be written? I wonder if OpenWRT has code built into it which can send jpeg files to the photoframe via USB, or if a special driver is required? I don't know much about USB interfaces, Linux internals, or graphic file formats. Writing a program to draw characters from an ASCII stream to a bit map in memory is something that I know how to do (because I know how to do that in hardware).

Thanks,
Lloyd

[jeroen94704]

I would like to know more about what you want to do. Do you have links to related work that other people have done?

My main source that helped me get something on the display was this site:

http://web.media.mit.edu/~gracewoo/stuff/picframe/

Are each of those items new programs that will have to be written? I wonder if OpenWRT has code built into it which can send jpeg files to the photoframe via USB, or if a special driver is required? I don't know much about USB interfaces, Linux internals, or graphic file formats. Writing a program to draw characters from an ASCII stream to a bit map in memory is something that I know how to do (because I know how to do that in hardware).

Apart from the jpeg encoding (which is done by libjpeg) and USB communication (libusb), pretty much the whole thing would have to be coded from scratch. This is not as hard as it may sound, actually. The main challenge is getting everything set up and working on the OpenWRT platform. Once you've got that working, it will be relatively straightforward to display text on the photoframe.

Still, if all you're trying to do is display ASCII-text, is a hi-res graphics display a logical choice? Although I can see the appeal, and of course you can show quite a large amount of information on an 800x480 display.

Jeroen