Rotation Sensor reading value that are way off

Programming Support
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1

Okay, so I’m working on implementing a rotation sensor for tracking my ladybrown position. When I run the code to move it, the arm maxes out it’s movement and tries to keep going. I have the code outputting readings to the brain, and while the target is correct, every other position is either -4194304 or INT_MAX. what might be the issue here? code below.

void armToPosition(double target) {
    double targetPosition = target * 100; // e.g., 4500
    double currentPosition = armEncoder.get_angle();
    int direction = (targetPosition < currentPosition) ? 1 : -1;

    pros::lcd::print(0, "Start: %d", currentPosition);
    pros::lcd::print(1, "Target: %d", targetPosition);
    pros::lcd::print(2, "Dir: %d", direction);

    //arm_motor.move_voltage(6000 * direction);

    while (fabs(armEncoder.get_angle() - targetPosition) > 100) {
        pros::lcd::print(3, "Pos: %d", armEncoder.get_angle());
        pros::lcd::print(4, "Error: %d", (armEncoder.get_angle() - targetPosition));
        pros::delay(10);
    }

    arm_motor.move_voltage(0);
    pros::lcd::print(5, "Stopped: %d", armEncoder.get_angle());
}
2

EDIT: I know that the move command is commented, out, we did that to rotate the arm and check encoder values, which all read the same as what I specified.

3

Are you sure you setup the armEncoder correctly? That reminds me of the error I had when I accidentally setup the sensor on the wrong port.

1 Like
4

we did double-check the port setup, yes. The encoder is set to Port 1 in the programming and is hooked up to port 1 on the brain. I do have the port reversed in the constructor, could that be the problem?

5

Based on PROS 4 Documentation for the Rotation Sensor:

get_angle returns “The angle value or PROS_ERR if the operation failed, setting errno”
PROS_ERR is equal to INT_MAX, or 2147483647, which aligns with your findings.

Therefore, your issue is most likely one of the following:
ENXIO - The given value is not within the range of V5 ports (1-21).
ENODEV - The port cannot be configured as an Rotation Sensor

Try checking the Rotation Sensor on the “Devices” section of your brain and see if it shows expected values.

6

the rotation sensor on the brain shows up and does show the expected values, and it is worth noting that I use PROS 3.8.3

7

It doesn’t look like much has changed in the front-facing API of the get_angle function from PROS 3 to 4 (PROS 3 documentation for reference).

Could you try printing the value of PROS_ERR right after you receive the return value of get_angle()? If it is equal to ENXIO (6) or ENODEV (19), then you have a bit more information to go after.