Reading Digital caliper with Arduino

[EdK]

Now that I got my hands on a scope that triggers properly, I was able to confirm that the protocol matches the PDF file by Rick Sparber.

http://rick.sparber.org/electronics/hf6.pdf

Here's what I measured with this scope. These are measurements taken from the Atmel IO pins, not on the digital caliper pins.

Clock high pulse is 205uS
Clock low pulse is 84uS
Time between nibbles is 374uS
Time between bursts of nibbles is 104mS

Those are pretty close to what I got using the first scope.

I've attached a couple of screen images from the scope. The first one is in inch mode and the second one in millimeter mode.

By using one of the unused IO pins, I programmed it as an output so I could toggle it for diagnostic purposes. I've verified that the interrupt is working properly since the ISR is triggering on the falling edge of the clock. The bit counter is also working since it counts up to 24 and then resets. The problem area yet to get working is the retrieving of the data. I'm seeing all bits being 1's which makes no sense. Now that I have a decent scope to work with I should be able to figure it out easier.

Ed