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Video overlay


Has anyone seen or tried video generation or overlay (with a composite video signal) with Fez or MicroCF? Any thoughts on if this is possible with a non-real-time OS? Or do I need to use an external real-time chip to handle that?

I have seen some I2c or SPI-connected devices that do the work for me (including character generation), but they’re a little pricy and don’t support much in the way of graphics beyond custom characters.


There are chips that do that and they are not pricey. Doing this in software is a bad idea.

It is $40 but you can look at schematic and hack your own for $10


Get a BOB-4SG board which will take SPI.

Or, make an AVROSD or PICOSD chip which you can control via serial. NetMF doesnt have anywhere near the speed to deal with something as fine as video sync signals. We write these in assembly on 8/16 bit micro’s in order to deal with the very very fine timing requirements.


Interesting… looks like I can find a good starting point for using a cheap PIC chip to do almost everything I need. I’ll start with the Maxim IC because that gets me 90% there. Then when I want more control of what’s on the screen (e.g. vector graphics, etc.) I’ll look into a PIC or AVR approach.

BOB-4SG looks great but I’m keeping it super cheap (although I’ll spend more in the long run, I’m sure.) :slight_smile:


I already have a MAX7456 breakout board from Sparkfun and I can highly recommend it. There is a lot of Arduino code (just google Arduino MAX7456) which is well written and easy to follow.

I am in the process of converting some of the code from C to C#. There was another member here who also used the MAX7456 and wrote some code for it and I have been in contact with him to see if I could get a copy. He told me that the MAX7456 worked a treat.

When I finish my conversion I am more than happy to put the code up for you to get.

Take Care


Absolutely, I’d love to see that code. I’m making my own breakout board because I’ll eventually make my own board for the autopilot/uav. Any working and tested code would give me a huge head start. I’m impressed with what I have seen done with the MAX7456. It’s more powerful than I first thought.


Hi andrejk
I could not send a note to you privately but I wanted to say thank you so much for posting your code on
Sadly work (merging IT of 2 companies) has been keeping me very busy so I have not had much chance to get into my workshop.
Your timely release was most welcome.

Again many many thanks


Cool! Glad to hear it. Ping me if you have any problems.

I’m going to try this with the Parallax Propeller as well. I need to do some graphics and higher resolutions. It’s overkill but there are other thinsg Propeller can do for me.