STV5730a Video Overlay

he PCB with all components etc. was purchased from this place . They do not however supply any useable software or programming info. I decided the board was cheaper bought than self built, so I ordered it a while ago. I needed an OK video overlay generator for my Amateur Radio/TV experiments. The data sheet for the stv5730a is available from here. And an application note from here. The data sheet and programming info for the PIC16F84 from Microchip, is available elsewhere, and everywhere on the web.

This Video Overlay/Generator is to be used in the ATV repeater LA1ATV, which is the first(?) ATV repeater in Norway, and is hosted by LA1T - The Tonsberg group of NRRL

The sourcecode is available now here The code has a few comments, and probably a few bugs.

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It is not easy to capture screenshots from a TV with an el cheapo web cam, but here are some images.


The yellow wire (eh..the wire closest to the PIC) is used for "sync detect" input to the PIC, since this is not available on the original board. It is connected to the "MUTE" output on the stv5730a, and to RB0 on the PIC. This pin goes low when a video signal is present on the input on the OSD chip, and the PIC then changes the mode of the chip from "Video full page mode" (video generator) to "mixed mode" where text is overlaid on the video signal.


Video full page mode


Mixed mode (overlay)