Quote:
Originally Posted by mikets
Wait, I found the scaling code in CANJaguar. It is in packFXP16_16. It means the full range is actually +/- 65536. So like I suspected, the outputValues in jag.Set() should always be in the range of +/- 1.0 and the CANJaguar module will scale it to +/- 65536 and send it to the jags. Then why do we need to multiply 150.0? I am confused.
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The actual range depends on the mode. Look at the documentation for CANJaguar::Set.
Code:
/**
* Set the output set-point value.
*
* The scale and the units depend on the mode the Jaguar is in.
* In PercentVbus Mode, the outputValue is from -1.0 to 1.0 (same as PWM Jaguar).
* In Voltage Mode, the outputValue is in Volts.
* In Current Mode, the outputValue is in Amps.
* In Speed Mode, the outputValue is in Rotations/Minute.
* In Position Mode, the outputValue is in Rotations.
*
* @param outputValue The set-point to sent to the motor controller.
* @param syncGroup The update group to add this Set() to, pending UpdateSyncGroup(). If 0, update immediately.
*/
Everything you see inside the CANJaguar class is to convert from the WPILib API formats (such as -1.0 to 1.0) into the binary format to send to the Jag. Since in speed mode, the units are
RPM, I don't want to control my motor +/- 1 RPM... that's too slow. I set the RPM range in my example to +/- 150 RPM cause it made sense for the mechanism I was sensing with that encoder.
In the case of RobotDrive, it computes a motor output +/- 1.0 based on joystick inputs. If you are not using motors in Percent Vbus mode, then that's probably not a good range. The RobotDrive class allows you to specify a scale value by calling SetMaxOutput(); with a floating point number to multiply by the +/-1.0 values that it computes before they are passed into the Set(); call on each motor.
Hope that's clearer.
-Joe