The application is an angle indicator facility for a automotive power steering gear test rig .

The Encoder is a 3600 PPR type with quadrature output.

The display has to indicate the current angle of the steering column driven by a DC motor.

This is an endurance rig and the steering column will be turned incrementally in both CW and CCW direction by the user to see the smoothness in control. In case of any jarring he needs to note the angle of turn and direction either CW or CCW.

I need an idea to generate the Direction signal from the quadrature inputs. Preferably with a few gates so that I get a High level for one direction and Low level for other direction. Thus apart from reading the Encoder pulses I will also monitor this "Direction bit" and when it toggles, start decrementing the current angle, reach Zero and then increment from there, till the next Direction toggle.

If I were to do this ( direction sensing ) in software, the load on the MCU will increase and hence the need to do it in hardware external to the MCU.

Any ideas ?

Thanks

Raghu