[Flashforth-devel] Shaft encoder options

[Bob E. <bob...@ti...>]

Hi Mike,

No, I don't have a good source for encoders I'm afraid, but see below...

High resolution shaft encoders are to be had 
http://www.bourns.com/ProductLine.aspx?name=magnetic_encoders but 
they're more expensive than I care to pay (£30 upwards) I've seen 
various diy techniques for radio tuning.

Probably easiest and cheapest is the use of a stepper motor in generator 
mode, see http://www.webx.dk/oz2cpu/20m/encoder.htm. Bulky, but as long 
as the motor generates a large enough pulse at slow speed it works.

A smaller low cost solution is now available using hall effect chips - 
see http://store.makerbot.com/magnetic-rotary-encoder.html. The chips 
alone are very cheap 
http://uk.farnell.com/jsp/search/browse.jsp?N=2031+203959&Ntk=gensearch&Ntt=magnetic+encoder&Ntx=mode+matchallpartial. 
I'm thinking of buying some AS5040 
http://uk.farnell.com/ams/as5040-assu/encoder-magnetic-rotary-10bit-16ssop/dp/1630800 
and button magnets and just wiring my own using 'dead bug' construction. 
OH2NLT uses that approach 
http://www.kolumbus.fi/juha.niinikoski/Hall_encoder/Hall_encoder.htm.

Your quad math library looks very useful for synthesiser control - I 
needed 38 bit math for the SI570 chip, so will now start on a driver for 
that.

I have a 2x16 LCD driver written - the PIC board came with this 2 wire 
circuit http://www.rentron.com/myke1.htm. I'll publish that in another 
email, it might be useful to someone.

Best regards, Bob