Member postings for Andy from Workshopshed

Averaging I think I can handle in code fairly easily. To be honest I'd not dug quite so deep into the data sheet as that, I was more concern with what external components were needed and how to communicate with the chip.

In theory compensating for non linearities should also be possible in code with but that would as you mention require some external system to calibrate it against or perhaps a second chip rotated with respect to the first. Perhaps I'll quiz AMS on it once I've got something to test against.

For the time being I'll just get it working. The averaging would be useful for my simpler technique as it will stop the display from flickering so I'll start on that first.

Thanks again for all the feedback and info.

Michael, Neil, thanks for the feedback, I'll look at the maths for my size of table which is likely to be in the 3in diameter range. I do like the potentiometer solution for it's electrical simplicity but I'm going to investigate the magnetic encoder chip technique. I'm not the first person to hook one of these things upto a microcontroller so I should be able to work it out. Here's a video of how they work, it's really quite clever, the one I'm looking at has a 14bit resolution which gives at best 0.05° accuracy, not bad for a £9 chip (magnet not included)

Ah no, I don't have a worm drive but will likely need something similar for fine adjustments as it could be difficult to align the table/chuck accurately otherwise. Will re-read Ivan Law's book to see if there is anything about how accurate things need to be.

I gave a demo of my work in progress rotary encoder at the London Arduino meetup yesterday and there was a very relavent question.

"How accurate does it need to be"

Currently I've got it at 1024 postions per revolution, which gets me about 0.3 of a degree. I've seen commercial sensors that can go down to 0.1 degree and by using the magnetic chip I mention or if I can get the optical mouse solution to work then I should be able to match that.

So how would I calculate how accurate the table would need to be for say cutting an 8 tooth gear?

Edited By Andy from Workshopshed on 14/05/2013 12:13:39

Ah yes, I've heard that can be done, understand now. Here's the link http://www.youtube.com/watch?v=bci7Gi05BNc

Edited By Andy from Workshopshed on 09/05/2013 17:17:45

I've been doing some experiments with optical mice, they seem quite fussy with regards aligning with a suitable wheel. In theory they can do 1000 DPI which should be plenty if it can be made to work.

I've also been looking at other options such as a multi-turn potentiometer and a rather clever magnetic chip.

That Arduino video Jason mentioned might have been this one that I made last year, if not I'd be interested to know