Pulse Voltage Question

[southernexplore]

Can the driver (Picstep) board work correctly if you only have 3.3 volts for a high and .145 for the low signal? I am trying to get my driversto run smoothly and be more dependable. If the drivers cannot be run on 3.3 voltshow doI get it to work?
Thanks
(Tommy C.)
Southernexplorer

[southernexplore]

Let me add that it does drive the motors but they are very rough and will not run at the same speed every time. I have 48 volt power supply with the drivers running 2.8 amp 3.2 volt motors, using Mach3. I can set up the motor tuning to run at a comfortable speed and run the machine for an extended period and it will do fine, I come back the next day and it starts missing steps like crazy. I have disasembled the entire machine looking for misalignment but everything looks good.
Tommy C.

[pminmo]

southernex....,
Are your referring to the brake,step and dir inputs?

[southernexplore]

I am talking about the step pulse in the picstep driver. I am measuring 3.3 volts with a multimeter. Will the driver work correctly with only 3.3v or should it have a full 5v?
Tommy

[pminmo]

If your referring to the steady state hi voltage at the step pin, pin 6 of the PIC. Then yes it should work if you have 5VDC supply for the PIC.

[southernexplore]

I am referring to the parallel port, pins 2-3, 4-5, 6-7 etc. I only have 3.3 volts coming from my computer going through the breakout board and farther to the pic pins to drive the LMD18245's. The motors are rough, noisey, grinding sounding, and are not consistant on torque. One minute I can run 150+ IPM and the next they will not run 75. I have disconnected the motors from the router and right now they will not run 75 IPM without even being connected. The "X" motor will push the gantry to 200+ IPM with no problems when they are running correctly. Now grant it I do not expect it to run this fast and it be consistent but I would like for it to run the same every day. I have checked the output connections on the drivers with a scope and the square wave is very fuzzy on the leading edge but very clear and distinct on the trailing edge. I have even tried programming a new pic and it still doesn't work right. My concerns is this, do I need 5v coming from the computer parallel port for the drivers to work correctly.

[pminmo]

No, your PIC has a lower limit for a logic high of 2V when you run a 5V power supply. Some of what you describe (sound) maybe mechanical resonance. Not knowing your system, if your running 360rpm on your stepper or above your definitely pushing the limits of most stepper motors. Is your motor 4,6 or 8 wire?

[southernexplore]

First, thanks for replying Phil.
My motors are 8 wire and they are wired parallel. In the above post I did mention that the motors have been removed from the machine and they still are rough, vibrate and miss steps very easy like they have no torque at all. Let me make sure I understand you, if I have 5 volts powering the pic, 3.3 volts from the parallel port is more than enough to swith the ports of the pic from a low to a high?

Thanks again,
Tommy C.

[pminmo]

yes