Trouble with Commander app: Using buttons to control motors

Question

I'm having trouble with the Commander app for Android. I've put an EV3 into set 8448. I'm using one of the large motors for propulsion and a medium motor for rack and pinion steering. I don't have the remote (using the education set) so I'm trying to use my phone as a remote instead. I downloaded the Commander app.

I went into "create my own". I can use a slider to make the car go backwards and forwards, however, I tried to set up two buttons for steering, one button to make the medium motor go one way and another button to make it go the other way. Only one of the buttons works. It's only possible to make the medium motor go one way, not the other. How can I make it so the button controls can control the motor in either direction?

Any help would be greatly appreciated.

Answer 1

You cannot have more than one control per motor. If you have two controls, the signals are essentially sent to the EV3 at the same time, so only the second one will seem to work because it immediately changes whatever what sent by the first.

In your example, with 2 buttons, the buttons either command the motor to move or stop. If neither button is pressed, both are telling the motor to stop, so no problem. But if you press the first button, it tells the motor to turn, but the second button is telling the motor to stop. Since the EV3 got the message from the second button last, the motor stops and it appears that the first button does not work.

So, if you want to use the Commander app for this, you will need to use a different control that can turn the motor in either direction with just one control such as a slider or tilt.