Value for money rotary encoder?

[741]

I am looking for alternatives, on cost grounds, to the Bournes PEC11.

Say 12 detents (not critical) and a push-button (ideally). I'd tend to look on eBay and I hope to avoid really poor quality types by asking for recommendations here.

[rhodges]

I like this Alps rotary encoder. It goes on sale for fifty cents from time to time:
https://www.goldmine-elec-products.com/prodinfo.asp?number=G20056

I have code for the STM8 here:
https://github.com/unfrozen/stm8_libs/blob/master/lib_rotary.c
https://github.com/unfrozen/stm8_libs/blob/master/lib_rotary.h

/******************************************************************************
The ALPS rotary encoder switch has 30 detent positions, each one spaced 12
degrees apart. The three (encoder) pins are A (left), Common, B (right).
Pins A and B should be pulled up to Vcc; 10K resistors are recommended to
keep current under 1mA. Here, the input pins have internal pull-ups of
about 40K.
Both A and B are stable at detent position, and both A and B will have
the same output. When the encoder is rotated clockwise, B will change
first, then A. For counterclockwise, A will change first, then B.
Instead of using Interrupt On Change, poll at a rate often enough to
catch the fastest transitions. One full revolution in half a second
might be a good starting point, which gives 60 pin changes per second,
or one every 16 milliseconds. Oversampling by 4 would give one poll
every 4 milliseconds, which is probably already a timer interrupt.
0.      Read pins A and B, save starting status.
Polling procedure:
1.      Are pins A and B the same?
        NO: Which changed from saved status? Set direction flag. Exit.
        YES: Continue to 2.
2.      Are A and B equal to last saved status?
        YES: Encoder at same detent position. Ignore. Exit.
        NO:  Save new status. Eval direction flag and indicate rotation.
*/

[ehughes]

Just posting this so it is not forgotten:

http://www.mkesc.co.uk/ise.pdf


Probably the most robust and simplest decoder I have seen. 

[741]

Thanks all.

It is good to know of a "value for money supplier" more stable than eBay, a known make too.

I'm currently using firmware incorporating the very neat 'mkesc' code as part of its design.


What do you use for pulse cleanup? I found the Bournes RC circuit not so useful, and am using one which recognises the fact that 'noise' = brief signals opposite to switch closed level.

That is, for an open switch I do not expect much in the way of spurious closed contacts. However, for a closed swich, the scraping will joggle the wiper to open-circuit in an erratic, noisy manner.

Thus far, I have found the attached RC network to be better than that on the PEC11 datasheet.