Analog control on TRex JR. Getting flashing green light

According to the manual, the flashing green status LED indicates that “safe start conditions are not met.” I’ve gone through the manual and I think I’m doing everything right.

Here’s my setup:

  • I have the controller connected to an Ardunio Uno. I am trying to control it via an analog output on the UNO - sending from 0 to 5 volts to control motor speed.
  • My motor is a 24 volt DC motor.

For Jumpers:

  • I have the mode select jumper shorting the left two pins, so I should be in analog mode.
  • There is no jumper on the channel mix jumper.
  • There is no jumper on the learning mode jumper.

On the motor outputs:

  • M1A is going to motor power, M1B is going to motor ground
  • Vin is 24 volts
  • GND is ground
  • M2 A and B are floating
  • M3 out and ground are floating

On the RC/Analog inputs:

  • Channel 1 rightmost pin is connected to an analog output on my UNO. The Uno will send 0-5 volts based on a potentiometer, I have verified this is working with a multimeter.
  • Channel 2 and 3 rightmost pin are also connected to the same output as channel 1 (I did this to see if it would help meet the "safe start conditions.)
  • Channel 4 and 5 rightmost pins are going to +5 VCC.
  • All other pins in that section are floating.

So any thoughts? I would prefer not to have to use the serial configuration program if possible, I don’t have a cable to connect to my computer.



Hello, Dave.

Do you have a common ground between the Arduino and TReX Jr.? If not, you will need to add one to ensure proper communication. It was unclear to me how you are converting a signal from your Arduino into an analog voltage. Could you explain more about what you are using to do that? What voltage are you applying to the input on the TReX Jr? Could you post the sketch you are running on your Arduino? Could you also post picture showing your connections?

- Grant


Yes, I have a common ground. I am using one of the PWM outputs of the Ardunio to send from 0 to 5 volts to the TRex, and I verified that that is working by using a multimeter. But correct me if I’m wrong, but I don’t think that’s relevant, nor is the sketch I’m using. Maybe if I was unable to get the motor to move it could be an issue with my sketch, but the Trex is indicating that the “safe start” conditions are not met. Shouldn’t I be able to get it past that point before I even run a sketch on the Ardunio? And I could give you a picture of my breadboard, but it’s pretty busy!

So please let me know if you have any suggestions.

We got your email, and it sounds like sending an analog signal close the TReX Jr.'s default neutral point of 2.5 V (instead of 0 V) fixed the issue.

- Grant