Hi guys,
The output from a Rotary Shaft Encoder(Quadrature Encoder) are given as inputs to a Quadrature decoder which basically gives out a UP/DOWN signal and a pulse count signal(which gives the total number of counts).
My questins are
a) A simple decoder using two D Flip-Flops for decoding the up/down signal and a XOR gate for the pulse count would be easy.But I read somewhere(don't remember where) that the above mentioned circuit will miss pulses when the direction is changed.How can that be eliminated.Are there any other ways of decoding digital quadrature signals.I can use PAL/GAL etc to implement the logic.
b) The Geckodrive series of Servo Controllers takes Step and Direction signals as inputs and controls the servo's using quadrature encoder feedback.The output from the quadrature decoder is given to an UP/DOWN Counter.The STEP and Direction signals are given to another UP/DOWN Counter.What I don't understand is that a Parallel Adder is used to add the above two counters and routed to a D/A counter from where PID control action starts.What exactly is happening at the Adder and it's ouput.I mean what are we getting by adding those both counters indefinetly.since the STEP & Direction signals are inputs(also set points) and Decoded Quadrature signals are also inputs(present position,measurement points).If you want to see the actual block diagram you can get it at
Thank You, prizark.