This example shows how to find the current position and use that to "seek" to a specific angle. Be sure to run the calibration program from the previous section first and change these lines at the top of the code with your servo's values:
# Calibration setup CALIB_MIN = 15377 CALIB_MAX = 42890
If you calibrated over a different range of angles, also change those lines to match.
Here's the complete code listing:
# SPDX-FileCopyrightText: 2023 Carter Nelson for Adafruit Industries
#
# SPDX-License-Identifier: MIT
# Example code for using analog feedback value to seek a position
import time
import board
import pwmio
from analogio import AnalogIn
from simpleio import map_range
from adafruit_motor import servo
# Demo angles
angles = [0, 180, 0, 45, 180]
# Pin setup
SERVO_PIN = board.A1
FEEDBACK_PIN = board.A3
# Calibration setup
CALIB_MIN = 15377
CALIB_MAX = 42890
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)
def get_position():
'''Turns analog feedback raw ADC value into angle.'''
return map_range(feedback.value, CALIB_MIN, CALIB_MAX, ANGLE_MIN, ANGLE_MAX)
def seek_position(position, tolerance=2):
'''Move to specified angle and wait until move is complete.'''
servo.angle = position
while abs(get_position() - position) > tolerance:
pass
print("Servo feedback seek example.")
for angle in angles:
print("Moving to {}...".format(angle), end="")
start = time.monotonic()
seek_position(angle)
end = time.monotonic()
print("Done. Move took {} seconds.".format(end-start))
print("Pausing for 1 second.")
time.sleep(1)
# Deactivate servo
print("Finished. Deactivating servo.")
servo.angle = None
When the code runs, the servo will move to the specified angles. The amount of time it took to get there will also be shown.
