EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: nForce on January 18, 2019, 08:11:39 pm

I would like to know how does it work the magnetic absolute encoder and incremental one? Not the optical one.
I have these 2 signals (in attachment) from the incremental magnetic encoder. How would I calculate the speed of the motor?
Thanks.

This is the same as optical encoders work.
The speed regardless of the direction (assuming that direction is constant)  just use any channel and measure the frequency (number of edge transitions in a unit of time). The RPMs are proportional to that value. Exact coefficient depends on the overall mechanical design of the system.

Ok, in my case it's:
(12.02 kHz * 60)/1024
From where do we get that 60 and 1024?
Thanks ataradov :)

1024 looks like the number of edges per revolution. Assuming you are counting only rising or falling edges, that would make your encoder to be 4096 steps/rev, which is pretty standard.
Where does 60 come from, I have no idea. Do you have any sort of gearing between the motor and the encoder?
In your case, if you count N pulses per minute, then RPM = N / 1024, since 1024 pulses constitute the full rotation.

kHz is in seconds, RPM is in minutes, 60 shows up in there somewhere.

Yes, that makes sense :)