You can use the program below to help determine the feedback values that correspond to your servo's range of motion.
If you want to calibrate over a difference angle range, change these lines at the top. However, 0 and 180 are the maximum limits.
# Calibration setup ANGLE_MIN = 0 ANGLE_MAX = 180
When the code runs, it will print out the analog reading values that correspond to the min/max angles. Write these values down - they'll be used in the other examples.
# SPDX-FileCopyrightText: 2023 Carter Nelson for Adafruit Industries
#
# SPDX-License-Identifier: MIT
# Example code for calibrating analog feedback values to servo range
import time
import board
import pwmio
from analogio import AnalogIn
from adafruit_motor import servo
# Pin setup
SERVO_PIN = board.A1
FEEDBACK_PIN = board.A3
# Calibration setup
ANGLE_MIN = 0
ANGLE_MAX = 180
# Setup servo
pwm = pwmio.PWMOut(SERVO_PIN, duty_cycle=2 ** 15, frequency=50)
servo = servo.Servo(pwm)
servo.angle = None
# Setup feedback
feedback = AnalogIn(FEEDBACK_PIN)
print("Servo feedback calibration.")
# Helper function to average analog readings
def read_feedback(samples=10, delay=0.01):
reading = 0
for _ in range(samples):
reading += feedback.value
time.sleep(delay)
return int(reading/samples)
# Move to MIN angle
print("Moving to {}...".format(ANGLE_MIN), end="")
servo.angle = ANGLE_MIN
time.sleep(2)
print("Done.")
feedback_min = read_feedback()
# Move to MAX angle
print("Moving to {}...".format(ANGLE_MAX), end="")
servo.angle = ANGLE_MAX
time.sleep(2)
print("Done.")
feedback_max = read_feedback()
# Print results
print("="*20)
print("Feedback MIN = {}".format(feedback_min))
print("Feedback MAX = {}".format(feedback_max))
print("="*20)
# Deactivate servo
servo.angle = None
When the code runs, it will print out the analog reading values that correspond to the min/max angles.
In the output above, the two values of interest are 15377 and 42890. Write these values down - they'll be used in the other examples.
Page last edited January 22, 2025
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