Maple Encoder interface. « LeafLabs Garden

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Maple Encoder interface.

(5 posts) (3 voices)

Started 2 years ago by bubulindo
Latest reply from gbulmer

bubulindo
Member

Hello,

I just got round to create a library to use an onboard timer as a quadrature encoder interface.

It is quite undocumented, but I've added an example where the Maple simulates encoder signals and all that is needed is to jumper the board's pins. I haven't been able to test it with an encoder as I haven't found one that works on 3,3V or 5V that wouldn't break my budget. Although the cheap chinese pcb encoders are terrible with bouncing and the internal filters of the chip can only do so much. :(

If anyone wants to give it a try and point out some improvements/bugs, I'd be happy to correct and upgrade.
Ideally this would be used with the HardwareTimer class, but I found that I would have to do some changes there and that would probably be an issue for compatibility.

The library is at:

https://code.google.com/p/maple-encoder-interface/

Any feedback is welcome. :)

Posted 2 years ago #
robodude666
Member

Pretty cool little library! I did notice this in the code.

In the constructor, you enable the timer using:

timer_resume(TIMER2);

shouldn't that be _TIMER, instead of TIMER2?

-robodude666

Posted 2 years ago #
gbulmer
Moderator

bubulindo - "I haven't been able to test it with an encoder as I haven't found one that works on 3,3V or 5V that wouldn't break my budget. Although the cheap chinese pcb encoders are terrible with bouncing and the internal filters of the chip can only do so much. :("

Approximately what is your budget for encoders? Are you trying to make 'knobs', or is it for motor position or something 'mechatronic'?

AMS (formerly Austria Microsystems http://www.ams.com/eng) make a bunch of magnetic encoders, which are relatively easy to get; though there is still the problem of building the mechanism.
http://uk.farnell.com/jsp/search/browse.jsp?N=107637+2031+203959
IIRC Bosch, and maybe Honeywell make similar parts.

Posted 2 years ago #
bubulindo
Member

Well spotted robodude, I'll correct it and upload a new version.
Although I tested this library with different timers and it worked. :S I'll investigate that later on.

@gbulmer, to be honest this came out of sheer boredom... although I'd like to later on play a bit with robots, for the moment I'm more interested in a home monitoring system, so I didn't really want to spend a lot of money just to test the library.

I did have one of those knobs and they are not great... I'll have a look at the options you listed and see if they are cheap and something I could later on use.

Posted 2 years ago #
gbulmer
Moderator

bubulindo - the AMS encoders, and similar devices, are popular with the Micromouse and robotics folks. They are used to measure position or speed for rotary motion from motors. Also Faulhaber and Maxon make DC motors with similar encoders built in. However, some folks use the AMS sensors (or equivalent) on lower cost motors.

If you look at a micromouse like Pete Harrison's (who is using the STM32F4 encoders):
http://www.micromouseonline.com/2013/02/16/quadrature-encoders-with-the-stm32f4/#axzz2V5aUMcXR
It uses an encoder count-change of 200/mm

Posted 2 years ago #

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