Quadrature encoding using eg TTL hardware?

Hi, Wondering if anyone has any experience of using a hardware (eg TTL) solution to implement quadrature encoding, ie to determine the direction of travel of, for example a shaft, based on two out of phase signals. (See http://en.wikipedia.org/wiki/Rotary_encoder#Incremental_rotary_encoder for a better explanation!)

My application is an aircraft (glider) simulator. One of the controls I have to interface is an airbrake, operated by a physical lever that is moved backwards or forwards. At present I have a button box with an 'open' button and a 'close' button. To mimic the airbrake opening I press the 'o'pen button, five times = fully open. The reverse for 'c'lose. I need to generate 'o'pen and 'c'lose pulses depending on which way the physical lever moves. Mechanically I can generate two 90 deg out of phase signals using two microswitches and 'castleated' tracks. My problem is detecting edges and working out the direction of travel from this.

I appreciate I could probably do this in software but, like I said, I'd really like a hardware (eg TTL) solution.

Many thanks.


solution to implement quadrature encoding

I assume you mean decoding as encoding is different:-

look at:-

Yes, I mean decoding.

Many thanks for the link. I don't need to count pulses, just generate an up or down pulse, which will simplify things slightly.