Re: Freqmod.o

[Jon Elson <elson-at-pico-systems.com>]

Brad Nowak wrote:

> Hmmm .. I read the linuxcnc.org handbook and it says about 
> freqmod. "Phase stepping requires the computer to output the motor 
> phase signals directly, the stepper driver is just an amplifier.".
>  
> I was planning to use a L298 dual H-bridge to drive my motors.
>  
>  A bipolar stepper motor would require two outputs for each of the two 
> coils in the motor. The steppermod module only has step and 
> direction. Am I misinterpreting something ?
>
The full step drive waveform really only needs 2 wires per motor.  For 
each motor coil, current is
either going one way or the other.  For a half-step drive, the current 
in a coil can also be off,
and that would require more wires.

Steppermod.o only produces step and direction, but freqmod.o can produce 
step/dir OR
the 2-wire phase signals.

Jon