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Servo calibration procedure

The standard pulse width for servos ranges from 1000 to 2000 microseconds: servos are supposed to move their arm to the 0 position when receiving a 1000 microseconds pulse, and move it to the 90 position when receiving a 2000 microseconds pulse.

However, many servos support or require a wider pulse range. HobbyKing's HXT500 servos, for instance, respond to a range of 720-2200 microseconds pulses, moving their arm by 110.

Entering the widest pulse range corresponding to your servos will achieve maximal mechanical resolution.

Prerequisites:

  • Perform the Potentiometer calibration procedure before doing servo calibration
  • If you want to calibrate a servo already mounted in a model, disconnect the linkage attached to the servo arm

Power-on the receiver, enter Command mode, and for each channel (following procedure is given for channel #1):

  • Set the lowest pulse limit:
    • Move the potentiometer to its lowest position
    • Print current value of PWL1
    • Change PWL1=PWL1 - 10%
    • Check if the servo arm has moved to a lower position; if true then retry with a lower value for PWL1
    • When reducing PWL1 has no more effect on the servo arm or if it starts moving erratically, you've found the lowest possible value
  • Set the highest pulse limit:
    • Move the potentiometer to its highest position
    • Print current value of PWH1
    • Change PWH1=PWH1 + 10%
    • Check if the servo arm has moved to a higher position; if true then retry with a greater value for PWH1
    • When increasing PWH1 has no more effect on the servo arm or if it starts moving erratically, you've found the highest possible value

See the Channel variables page to learn more about PWL and PWH variables.

Read Servo control interface in detail for more information about servo pulses.

 
Page last modified on July 05, 2013, at 03:12 PM