PDA

View Full Version : Use of Prop. to display real-time video image



Frank70
05-19-2008, 07:15 AM
Hi all, I'm a newbie to Prop spin but I'm really excited about learning how to use spin and the Prop micro-controller for my project. I'm still waiting on the demo board and have started to read the manual for spin software and the Prop. as well. I would like to use the Prop. for trans. of a real-time video image from a ccd board camera to a LCD. I'm thinking of using the uoled96 for the display. I'm sure I will have to use a ADC for the composite video output of the ccd camera. has anyone had experience with this type of project that can warn me of any potential pitfalls? Is this even doable? http://forums.parallax.com/images/smilies/cool.gif

StefanL38
05-19-2008, 07:40 AM
hello,

here is a thread about a camera connected to the propeller


http://forums.parallax.com/showthread.php?p=592076

best regards

Stefan

Frank70
05-19-2008, 08:04 AM
Thanks I'll check it out!!

Ken Peterson
05-19-2008, 09:30 PM
If you plan to sample composite video in full color, you'll run into difficulties with the Propeller. The color information is a phase shift modulated 3.58MHz carrier superimposed on the amplitude modulated luminance. It is serious challenge, if not impossible, for the Propeller to move data that fast. I'll be very interested to see if someone can pull this off without a significant amount of external hardware.

You can, at least theoretically, sample the luminance value (B/W only) at 2.5MHz with a 5-bit depth using delta-sigma A/D, or at a faster rate using an external A/D chip. While you're adding external chips, a sync separator will dramatically simplify your code.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔


Post Edited (Ken Peterson) : 5/19/2008 1:35:22 PM GMT

rjo_
05-21-2008, 11:10 AM
everything above is true... but don't be discouraged. Exactly what are you trying to do? Regardless of your answer, the Prop can be part of the solution, but not necessarily the whole solution...

For example...if you want to sample data and time is not an issue you could use a serial camera and and sample it directly (or quickly store the image to a uSD and then take as much time as you like to sample through it.)

Right now my favorite video implementation is the overlay board by Hitt consultants... with this board you can take an ordinary video signal and overlay Prop data and record the whole thing to tape or disk... but the image is still analog.

If you are thinking about directly looking at the video data and you don't want to add much hardware... you are going to have to work around the technical limits of the current hardware or wait for the Prop II.

Minimize your specs to match your problem... there will be a way to do it, but there is no general solution.

Rich

Ken Peterson
05-22-2008, 09:09 AM
We're working on a project to sample video from a camera (NTSC Composite) and send it to a low-res VFD display. I'll try to keep you posted how that works.

My comments above were not meant to discourage, only to help Frank70 understand the complexity of sampling video. It's a challenge, but challenges are what drive innovation!

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔