SS and spindle motor control

[hunserv]

Recently I built an PWM-Analog converter of active filters, with adustable amplification for better calibration.

Now as I use it I had other questions raised:

* Does anyone how the PWM resolution changes with PWM frequency?
(Separately for PP output and for SS output)

** At Ports_Pins config, I can only set Step/DIR pins for spindle. IF I configure PWM, then STEP pin becomes the PWM output. OK. ANd what about the DIR pin?
 - If I set it to 0 (supposing I always rotate my spindle one direction only) then mach yells for an error.
 -- If I set it to a certain pin, then what will it do??? (I can configure separate relays for CW and CCW but I do not see where to  assign pins for them)
 --- What If (and this is my case in fact) want to use one pin for direction (HIGH=CW; LOW=CCW) and another pin for Spindle START/STOP (HIGH=GO; LOW=STOP) and a third pin for the PWM signal for speed control?

[Peter Homann]

Hi Hunserv,

For the parallel port, the resolution of the PWM is the Mach3 kernel speed/PWM base frequency

So, if you have a Mach3 kernel frequency of 45KHz and a PWM base frequency of say 10Hz, then the resoulution  of the PWM output is 45,000/10 = 4,500 steps between 0% and 100% of maximum speed. So that is 0.022%

Therefore if you have a maximum spindle speed of 10,000rpm, the speed resolution you can get is 10,000 / 4500= 2.22 rpm

For the smoothstepper, I'm not completely sure but I think that the equivalent value for the kernel speed is 4MHz so the resolution is a lot higher.

Cheers,


Peter.

[hunserv]

Thanks Peter,

Any hints on the 3-wire spindle setup? (pwm, dir, stop)