Generating a composite video signal with PIC

Hi, I had a random idea earlier to try and output a video signal from a PIC chip into my TVs composite socket. Its something ive been thinking about for a while and i would like to learn it. Ive been searching the net for a few hours and found a few sites where someone has made a game etc with a PIC. They dont seem to have much information about how they did it though. One site did mention a PIC16F84A which i just happened to have laying around so i connected it up to see what would happen.

Ive been messing around with this circuit for a while now and i get lots of grey lines on the screen that change when i change the timing of the pulses. As i already know, one site mentioned that timing is critical. The problem is that nowhere seems to give any infomation on the timing.

At the moment i simply want to get the timing correct so i can program in some basic black and white shapes. After that ill move onto color images. Does anyone have any good links to sites describing how to do this? The closest i found was some ASM source code (which i dont understand)

Edit: I should mention that im in the UK so ill be using PAL.

Quote:

---

Originally Posted by The Master

Hi, I had a random idea earlier to try and output a video signal from a PIC chip into my TVs composite socket.

---

Been there, done that.
Google Pic-Pong or Pic-Tock...and Rickard and you'll find a few sites with his version of a Pong game on a PIC. And if you look around the site enough (ok, if you actually just look), you'll find PAL and NTSC spec's. And if you Google PAL and/or NTSC, one of the first hits is to Wikipedia, which has a good writeup on the PAL and NTSC standards, timing, etc.

Quote:

---

After that ill move onto color images.

---

Probably not going to happen with a PIC...ok, most likely not going to happen with a PIC. Doesn't run fast enough, can't output the signals quick enough to generate the colorburst phase shifts that color requires. The SX can do it at top speed, but just barely.

Quote:

---

Does anyone have any good links to sites describing how to do this? The closest i found was some ASM source code (which i dont understand)

---

Google...
Most likely, all your going to find is ASM code. The timing is just too critical to trust to Basic.