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Control Gecko Drives — Parallax Forums

Control Gecko Drives

max711max711 Posts: 8
edited 2012-06-10 11:52 in General Discussion
Hi, newbie here looking for a little advice.

I have a G320 Gecko driving a 12v DC motor with an encoder. I need to send step and direction signals to the Gecko drive. It needs a 5v pulse and I need 97 pulses per second +/- 3 pulses per second accuracy.

Ramp up and ramp down would be nice and the ability to program different rates too.

Small footprint is also important. USB interface would be nice.

Which of the parallax products would work best for this application?

Thanks

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2012-06-10 10:46
    You didn't provide any information about the G320. Usually it's best to at least provide a link to some kind of manual. You also need to describe better what you want to do with this. Do you just want an interface between the G320 and a PC? Do you want to do something more complex? If I were doing this myself, I'd probably use a Propeller Servo Controller since it has a USB to serial interface built-in and has a 5V level translator chip. The Propeller operates with 3.3V logic levels. Most of the time, the 3.3V logic levels interface just fine with 5V logic like that of the G320, but, without a real datasheet, I can't tell how the G320 will do. The Propeller Servo Controller comes with firmware for controlling standard hobby servo motors, but this firmware could easily be replaced with a program to control a stepper motor which is what a G320 pretends to be. There are some objects in the Propeller Object Exchange (click on OBEX above) for controlling stepper motors and you could probably adapt one of those to use.
  • max711max711 Posts: 8
    edited 2012-06-10 11:26
    Thanks for the reply.

    I had a typo, it's a G340 servo drive http://www.geckodrive.com/g340.html

    Looks like the step and direction signals have to be between 4.5v and 5v.

    Basically all it needs to do is send step signals to the G340. It needs to work in stand alone mode (not connected to a PC), but connect to a PC when I want to program a different step rate. Eventually it would be an interface between the PC and G340 so I could do more advanced control strategies.

    Looks like the PSC would fit the bill if it can output accurately timed 5v pulses?
  • Mike GreenMike Green Posts: 23,101
    edited 2012-06-10 11:49
    The PSC, as I mentioned, has a voltage level translator chip on its outputs that translates the 3.3V logic levels to 5V levels. It's intended for use with servo motors, but should work fine with the G340. The G340 inputs seem to be opto-isolator inputs.

    The Propeller uses a system clock of 80MHz and can time pulses to 12.5ns granularity. You've got more than enough time available to write your programs in Spin or C if you want. There are several examples of stepper motor drivers in the OBEX.
  • max711max711 Posts: 8
    edited 2012-06-10 11:52
    That's great! Just ordered the PSC

    Thanks so much for the help
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