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Quadrature Encoder Interfaces with Mbeds

Topic last updated 27 Apr 2011, by Hexley Ball. 2 replies
Joshua Burns
27 Apr 2011

Are there two quadrature interfaces on the mbed micro controller? Is there a way to hook up to the interfaces through the pins and communicate with them?

Andy K
27 Apr 2011

There's only one (QEI, Chapter 26). However, one of the GPIO pins is connect to an LED on the Mbed. The other isn't connected at all (neither is the index iirc).

Your only other solution is a software version based around GPIO interrupts. There are a few in the published libraries. You'd have to search for them however.

Hexley Ball
27 Apr 2011

Joshua, if you want to hook up to the internal QEI hardware you'll have to get out your soldering iron. See my notebook page http://mbed.org/users/hexley/notebook/qei_hw-interface-implementation-notes/ for a writeup with photos on how to connect to PhA and PhB.

BTW, I also have published a driver, QEI_hw, that supports the internal hardware.