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Pi Zero used as USB device to output .JPG's as PAL video

Posted: Wed Nov 16, 2016 6:54 pm
by HopmanUK
I have an idea for a possible project, but am not sure if it is something I could possibly do using a Pi Zero.. maybe some of you with more knowledge can point out possible issues..

I need to be able to take an image (eg. jpg, tif etc.) that is currently in memory on a Pi 2 and somehow output it to video out (to an analogue printer).

In essence, if I had access to the 3.5mm jack on the pi I could possibly change the video output and do it that way, but unfortunately in this case I don't have access to it. I do have access to the USB though.

So... could I use a pi zero set to be a USB gadget (maybe as mass storage?) which then watches for files sent to it and then outputs the image to its screen (in this case the composite video).

Any feedback would be fantastic.

Thanks

Rich

Re: Pi Zero USB device to composite video

Posted: Wed Nov 16, 2016 8:04 pm
by rpdom
The Pi Zero has analogue/composite video out on the holes marked "TV". You just need to solder pins or a cable to those holes.

Re: Pi Zero USB device to composite video

Posted: Wed Nov 16, 2016 8:18 pm
by HopmanUK
I was aware of that, thats why i was considering the zero.

Its more whether it would be possible to have it running as a usb device with some code running on it to actually do the output to composite (plus probably a signal line to cause the printer to print).

Thanks

Rich

Re: Pi Zero used as USB device to output .JPG's as PAL video

Posted: Thu Nov 17, 2016 6:30 am
by ghans
Do you have root on the Pi2 ? Just make the Zero
emulate an Ethernet device( g_ethernet). You can now use
SFTP to transfer files to the zero and SSH to start
an image viewer on the Zero.
You need to be practically and legally able to modify
and execute commands on the Pi2 for this to work
though.


ghans

Re: Pi Zero used as USB device to output .JPG's as PAL video

Posted: Thu Nov 17, 2016 8:36 am
by HopmanUK
That sounds like it might work. I do have access to the root account so I will give it a go.

Thanks

Rich