composite video output

the STV5730 chip does what you need, example here:

Best regards

"Xarion" schrieb im Newsbeitrag news:dcn95e$5f6$ snipped-for-privacy@ctb-nnrp2.saix.net...

Hi again!

I see that is what i need. so basicalluy i could use a microcontroller instead of the parallel port to gernerate the necessary text on the screen?

It says it can use a video input as the background etc... Is there some way in which i could store an image into a RAM for example and then encode it into that composite signal? what sort of device would do this?

- Xarion

"Xarion" schrieb im Newsbeitrag news:dcncln$a4d$ snipped-for-privacy@ctb-nnrp2.saix.net...

yes, only a serial interface is needed to control the OSD generator, you can use a microcontroller or even the parallel port of your computer if you want (and simulate the serial data with bit banging).

I have no idea about how to easily generate the background except by using for example a small CPLD connected to a RAM for generating a video signal with the background you need but you must know PLD programming and add some more hardware etc... it's according to your skills...

Sorry to ask this but what is a CPLD?

Xarion schrieb:

Hello,

I worked with a module consisting of several chips. This module was able to do what you want. But the module needed for the encoding of an image into the composite signal a RAM large enough for the pixels of the image, a fast DA converter and the necessary timing logic for the generation of the pixel clock frequency.

By the way, are you talking about a black and white image, or an RGB image? RGB would three times more RAM and three DA converters.

Bye

cpld - complex programmable logic device

basically programmable logic blocks connected by a programmable interconnect(switch matrix)

You can make or design your circuit using either schematics or a hardware description langauge(vhdl or verilog) or logic language like abel

The big two programmable logic companies are

others include Lattice , Actel, Atmel

xilinx cplds

Can still get cplds but the largest market share of programmable logic is fpga fpga - field programmable logic array a sea of gates or very small blocks again connected by a switch or routing matrix.

Can use them for lots of things from custom micro controllers and controllers , software radio and signal processing , video and even for prototyping chips. Find them in things like plasma screen tv's , mobile phone base stations.

Most of the companies sell cheap starter kits.

xilinx sell their Spartan3 starter kit for US$99

Their spartan3e kit is supposed to be available in september for US$149

Alex

Only one D/A converter needed for COMPOSITE color - do the phase modulation in digital. Old personal computers handled it pretty well - just use a pixel clock at four times the color subcarrier, they didn't even have a D/A converter, they did digital discrete colors by the pattern of 4 bits corresponding to one period of the color clock. It's also debateable if this takes any more memory than monochrome - if you send the colorburst and thus enable the color decoder in the monitor/TV you can't have too fine a spatial resolution anyway without introducing artifact colors.

A single 8-bit D/A converter and a preculculated ram buffer can do a quite nice job of showing a TV-quality color background, even with the sync signals generated by the D/A rather than generated externally (though this does limit the dynamic range available for the picture).