While waiting for your response to my previous email…I went ahead & wired the ADC 08100 as follows:
D0-D7 wired to P0-P7 & ADC_Clock_pin wired to P8. From the source code in ViewPort it appears VIDEOSTART connects to D4-D7 for P4-P7 (VIDEOSTART + 3) & ADC_Clock_pin is P8. I did this because the textbook shows D0-D7 going to P16-P23 which are already tied to resistors for TV & VGA connectors in the DEMO boards & Proto boards. P16-P23 are tied to LED’s on the QuickStart boards as well.
P8 is wired to the Microphone on the Demo boards (which I’m not using for this design)…it’s OK on the Proto boards & QuickStart boards. P0-P7 are also wired to pushbutton inputs thru 100K resistors on the QuickStart board, but that’s not a problem either if the pushbuttons aren’t in use. Now…I had an idea for using a "4-bit window" that slides within the 8-bit ADC output.
Since ambient lighting conditions in my application will vary (outside 24/7)…it seemed like the signal level would vary. By testing the VIDEOSTART value…the window could slide left or right to increase or decrease sensitivity. For example, if signal < 5…rotate left to double sensitivity or if signal > 10…rotate right to antennuate signal by half.
I haven’t built the circuit yet to see how it looks in ViewPort, so I don’t know what effects, if any, it would have on the sync signals & their proper detection. Please let me know what you think & how this might be done in modifying the code. Thanks again for all your help…