- This project is designed to show how to build time-dependent applications on PICs in C and to deal with restricted hardware.
- It will also help you to have a start point, if you need a simple way to add text to a PAL composite video signal in real time.
- With only an 8 pins PIC and a few cheap components, you can superimpose constant or dynamic text to a composite video PAL signal.
- To superimpose text to a PAL video signal, we need to control timing with precision to get a stable picture.
- We have to deal with vertical synchronization, which tell us when a new frame starts, and with horizontal synchronization, which tell us when a new line starts.
- External circuit is used to extract both vertical and horizontal synchronization pulses from the PAL video signal.
- The LM1881 integrated circuit does it very well for example.
Details can be found HERE