Rupp;Rupp said:I must admit I have the attention span of a 4 err 3 year old so it lost me when all the math started.
Remember that this How-To uses an abridged explanation for all the math. Make sure you go through the Analog to Digital Converters Guide to get a more detailed explanation of using the slope intercept formula (didn't want to go through that much detail here as I wanted to concentrate on the hardware and methodology specific to monitoring the garage door).
It's pretty simple and the Guide offers a very detailed step by step approach. Please let me know if you have any problems as I may modify any parts that don't make sense.