In the previous section you learned how to set the motor to run at a specific power level in a specific direction. However, in most applications, it will be necessary to control the motor with a gamepad, to easily change the direction or power level of a mechanism.
We are able to use a button to set the motor to a specific power or we can program it so it changes based on the direction of one of the gamepad's joysticks!
Using our existing test_motor.setPower(1); we can replace the value of 1 with this.gamepad1.left_stick_y;
Now the power of our motor will be set in response to the position of the gamepad's left joystick as it along the y-axis!
Build your OpMode and test it out with your gamepad! Think about the following questions while testing:
What happens when you move the left joystick up a small amount versus a large amount?
What happens if you move the joystick to the left or right along the X-axis?
What happens if you move the joystick at a diagonal or rotate it 360 degrees?
You may notice that when moving along the X-axis nothing happens at the moment. However, once the joystick hits an angle near the Y-axis vertices the motor may start to jitter and spin.
When you tested your program, did the motor spin the expected direction while moving the joystick up or down?
In the FTC SDK for most controllers the Y value of a joystick ranges from -1 when a joystick is in its topmost position, to +1 when a joystick is in its bottommost position.
That may be a little confusing to control, but we can add a negative symbol, or negation operator, to the line of code to change the direction of the motor in relation to the gamepad.