I am building a circuit board to listen to quadrature encoder signals from a motor controller and send these signals on to an FPGA that will be used to count the pulses and direction. The signals coming out of my motor controller are:
- Phase A: A and !A
- Phase B: B and !B
- Phase C: C and !C (origin indicator)
In other words, each phase sends out two signals that are the opposite of one another at all times. I have used Quad EIA-422/423 (MC3486) line receivers to convert differential voltage signals into TTL signals, but is this the correct component for converting each phase from two signals to a single TTL signal? If not, is there a similar IC that will do the trick?
EDIT: It looks like I was treating these signals correctly. I was a little confused on the definition of "differential voltage" as it applies to the line receivers I am using (MC3486). Basically when A is
high and !A is
low, my line receiver outputs a
high on the TTL channel. When A is
low and !A is
high, it outputs a
low on the TTL channel. This is what I wanted it to do; I was concerned that I had misinterpreted the meaning of differential voltage.