Using Cheap Chinese Calipers as encoders

[tenaja]

Speed isn't going to be the issue. My problem is how do I retreive the data from a 48 Bit data stream with a 16 bit word capable Microcontroller, I am guessing it can be done as at least 3 comercial enterprises use them as the basis of a DRO, my math skills and inadequate experience in programming are such that I am looking for suggestions as to how to accomplish this feat, mind you, not a code author, but some pointers. Would you store it in 3 words ? Would that involve using an array, something like:<p>

MyData var word[24]<p>

The PIC only handles 8 bits--your limitation of 16 is within the compiler, which you can always try another. If you want to stay with the existing one, then the array is probably the best way to go. You'll just have to work out any math commands that you want.

[arniepj]

I have read the 52 bits of data out of a Mitutoyo dial indicator with a pic.The clock signal is tied to an interrupt pin and the data is read into a 52 bit array.The data can then be manipulated however necessary.The Chinese calipers while different, can probably read in a similar manner.

[Archangel]

Thanks arniepj,
So if I got this right, output the clock and data pins through a couple of comparators or OPAmps, to get levels up to 5 volt levels, and hook the clock pin to an interrupt on change pin then read the data into array, sounds simple enough, I have to read up on getting the data out of an array, in a way I can use and understand it.

Thanks
JS

[arniepj]

I used a 16F877 with the data tied directly to portb.1 and the clock tied directly to portb.0.Enabling the weak pull up resistors was all that was needed.I believe the signal voltage levels were on par with the caliper levels.Looking at the link waveforms,I would start by capturing the pause in between the clock pulse groups as an indicator to start clocking the data.

[Archangel]

Thank You.