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Propeller interface with Motor Mount & Wheel Kit (#27971) question — Parallax Forums

Propeller interface with Motor Mount & Wheel Kit (#27971) question

LarryCardoLarryCardo Posts: 28
edited 2011-02-21 08:36 in Robotics
I am sending commands to the position controller from the propeller--but getting unreliable results. As the controller is a 5 volt device and the Propeller is a 3.3 volt device, do I need something between the two?

I am using only one Propeller I/O pin and full duplex. serial plus for communications.

Larry Cardo
Mentor, OH

Comments

  • dandreaedandreae Posts: 1,375
    edited 2011-02-17 07:41
    Can you post your code and a picture (close-up) of your set up?

    Thanks,

    Dave
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2011-02-17 07:59
    You should have a 1K resistor on the Propeller pin going to the position controller and also make sure they have a common ground. How do you have things wired up? Also, how are the jumpers configured on each position controller?

    Robert
  • LarryCardoLarryCardo Posts: 28
    edited 2011-02-19 08:10
    Thanks Dave and Robert,

    I am connecting to the motor controllers by a daisy chain. The first motor in the chain has the jumpers set to ID 1 and the second motor set to ID 2. I have the propeller supplying the 5 volts to the controllers. Yellow is connected to M1 and blue is connected to M2 on both motors HB-25s. The HB-25s are connected to each controller.. I am using a heavy duty 12 volt PSH-1280F2-FR that Dave recommended. Propeller Pin one is the data output to the controller, with a 1k resistor in series.

    I am using 3 software programs I download from OBEX, all with similar results (WC_Test Harness, MC Roll Demo and Wheel_Controller. And getting similar results from each.

    Today, I am going to check all motor wiring again and ohm out each cable. Then I am going to only connect one motor, controller and HB-25. Then I am going to see results and swap controllers and HB-25s.

    Thanks,

    Larry
  • LarryCardoLarryCardo Posts: 28
    edited 2011-02-21 08:36
    Problem solved.

    First using a 1K resistor, communication between a 5 volt device and a 3.3 volt device is working.

    Second, reversing the wires on the motors fixed the control problem. The instructions could be clearer on this point, as I see other people have had the same issue. When 2 motors are used, there is interaction with three varables. The yellow and blue wiring, the ID of the motors and the SERV command for either right or left motor. If all three elements are not correct, the motors will run away from their controlled position and after about 20 seconds begin a violent back and forth movement.

    Larry Cardo
    Mentor, OH
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