NTSC TV output with 27 MHZ DCLK

robertcharnock9 · ‎2004-09-21

Posted on September 21, 2004 at 11:25

robertcharnock9 · ‎2004-06-16

Posted on June 16, 2004 at 18:05

Using a Consumer II C5, what registers need to be changed and what are there values to have improved quality on NTSC with 27 MHZ CLK ?

I asked this same question using ''The ST Microcontroller (MCU) support Site'' over a week ago, no response yet.

We have tried Changing DDC Control Register, 3Fh bit 3, and TV

horizontal Active Video Start B, 42h, bit 5. per table 12-22 of STPC Consumer-II Programming Manual, Issue 1.2, February 8, 2002, to NTSC Enabled. It didn't work.

Is there a App Note on this?

Any help would be appreciated.

marios · ‎2004-07-19

Posted on July 19, 2004 at 16:06

First you have to know if your expectations of NTSC quality match the capabilities of the output of the ConsumerII part. I'm not even sure if it can compare to the output of those VGA-to-NTSC dongles that are availble on the market. Have you compared it to other products with a similar technology?

Many factors make an NTSC output look good or bad. The quality of the video itself is most frequently measured with a vectorscope, where you can get info about the precision of the encoding. But this implies that the other timing parameters are respected, like the sync positions and lengths. From your question it looks like you're trying to modify the timings. If you can provide a more precise description of the problem (more than: bad video) you increase the odds that someone faced a similar issue. Are you using the Eval board? Are you using an external clock signal for the dot clock?

kaouther · ‎2004-09-21

Posted on September 21, 2004 at 11:25

Hi,

Yes there is an application note for this ''AN1331'' available on our web site.

Thanks.