Iñigo Garmendia

Direction detection in Quadrature Decoder

Discussion created by Iñigo Garmendia on Mar 23, 2006
Latest reply on Nov 21, 2006 by Fabrice Courtois
We are programing Freescale 56F8357 DSP in Metrowerks CodeWarrior IDE version 5.6.1 1658 environment.
We have a problem using Quadrature Decoder. We have an encoder that gives us two signals with 90º phase difference.

We need to obtain the direction of spin given by the encoder. For that goal, we have readen in "MC56F8300 Peripheral User Manual Rev 4.0" Page 12-5 that: "The direction of the count is determined by direction signal". But how could us obtain this direction? it appears in a register? or we have to deduce from "POSD" register? Does this register give negative values if the encoder gives back-direction values? How could us proceed?
Thank you very much,