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1  Forum 2005-2010 (read only) / Interfacing / Re: Interfacing with an NTSC TV on: December 29, 2009, 04:46:16 pm
I had a hard time getting this code to work.  It wasn't sync'ing, and I had to drop the delays down really far to get it to be stable.  Something like:
ntscDelayHSyncStart  3 us
ntscDelayBackPorch  1 us
ntscDelayFrontPorch  1 us
ntscDelayPerLine  2*21 us
ntscDelayVSync  25 us

Is it common to have this problem (not sync'ing -- screen is a rapidly moving mess of short horizontal lines) with the original values?  Does this mean my board is slower than standard?  Or that something else is slowing it?

> Is it possible that arduino timing has changed?

Perhaps delayMicroseconds was significantly changed over the past couple years?  I just compared 0007 and 0017... The only difference I see is the addition of a local variable and saving/restoring the interrupts SREG.  Just a few clock cycles I would think.

My specs:
- Duemilanove with ATmega328
- arduino version 0017

Also... i modified the code to allow interactive changing of the delay values, and then to allow 4x the precision in delay values.  I could post this messy code if anyone else has trouble with the "standard" delay values; let me know.

Thanks for the code and for any advice about why I'd need much smaller delays!
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