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Topic: Generating Composite Video (Read 15 times) previous topic - next topic

Golan

Hi All,

Possibly this should be a new thread, but the "generating video bboard" is pretty close to my question:

Has anyone written code to detect the vertical blanking interval in an incoming NTSC composite video signal (RS-170A)?

I'm creating a project in which I need to switch a circuit on and off, precisely in sync with the video fields from an NTSC video source. In order to do this, I would need to sample the video signal fairly frequently and write an analyzer/detector for the vertical blanking interval, which is used to synchronise the video frames.

Any advice would be greatly appreciated before I bore headlong into the oscilloscope.
Thanks,
Golan



XNDR

I stumbled upon a site where they sell all kinds of electronic video/audio instruments. There's a lot of interesting information about how these guys managed to get the video output running.. They use a ARM7TDMI Microcontroller in conjunction with an AD725 RGB to PAL/NTSC encoder IC from Analog Devices. They run a crystal at 4 times the video burst frequency to get stable output, it still only handles 256 colors at a 160 x 128 resolution. But it looks like lots of fun to play with, it could also be interfaced with an arduino board. Programming the microcontroller itsself requires C skills and the GNU toolchain, a flash utility and an USB board (i bet the arduino can also be used as an Serial/USB interface to program this board).

http://www.critterandguitari.com/catalog/index.php?main_page=product_info&cPath=1&products_id=13

zitron

Hey Benoît ROUSSEAU,

Just want to say good luck! I hope you'll find a way to get it to work eventually, meanwhile I can dream about arduino pong!

-Z-

Benoît ROUSSEAU

Hello,

 Yes, I'm thinking about soltions with external components. But, at first I want to do it the best without active components. It's a challenge with Arduino Board  :). I will try with some asm code include in  C code...
Cordialement,
Benoît ROUSSEAU

jlulian38

Maybe this is just crazy talk, but couldn't you try and generate your sync signal with a bi-stable oscillator, you'd want to watch that with the MCU so that you don't keep sending data as your sync goes off, if not using the oscillator directly, you could use it to keep track of were you are in your output (send the sync with the MCU, but use the oscillator to time everything right.

(Please excuse any tyops I've made, it's late, and it's hard for me to keep up with my high standard of typing when I'm tired.)

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