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我尝试学习如何使用 PCA9685 模块来控制带有树莓派的伺服系统。我正在关注提供以下代码的 adafruit 教程：

# Simple demo of of the PCA9685 PWM servo/LED controller library.
# This will move channel 0 from min to max position repeatedly.
# Author: Tony DiCola
# License: Public Domain
from __future__ import division
import time

# Import the PCA9685 module.
import Adafruit_PCA9685


# Uncomment to enable debug output.
#import logging
#logging.basicConfig(level=logging.DEBUG)

# Initialise the PCA9685 using the default address (0x40).
pwm = Adafruit_PCA9685.PCA9685()

# Alternatively specify a different address and/or bus:
#pwm = Adafruit_PCA9685.PCA9685(address=0x41, busnum=2)

# Configure min and max servo pulse lengths
servo_min = 150  # Min pulse length out of 4096
servo_max = 600  # Max pulse length out of 4096

# Helper function to make setting a servo pulse width simpler.
def set_servo_pulse(channel, pulse):
    pulse_length = 1000000    # 1,000,000 us per second
    pulse_length //= 60       # 60 Hz
    print('{0}us per period'.format(pulse_length))
    pulse_length //= 4096     # 12 bits of resolution
    print('{0}us per bit'.format(pulse_length))
    pulse *= 1000
    pulse //= pulse_length
    pwm.set_pwm(channel, 0, pulse)

# Set frequency to 60hz, good for servos.
pwm.set_pwm_freq(60)

print('Moving servo on channel 0, press Ctrl-C to quit...')
while True:
    # Move servo on channel O between extremes.
    pwm.set_pwm(0, 0, servo_min)
    time.sleep(1)
    pwm.set_pwm(0, 0, servo_max)
time.sleep(1)

一切正常，伺服正确移动 - 但是当我退出程序时，伺服仍然接收到一个信号，迫使它进入一个方向。如果尝试添加键盘中断和中断语句，但这会导致伺服器严重升温。现在我害怕打破一些东西。所以我想知道退出程序后如何停止信号？

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1 回答 1

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如果您的程序退出，您肯定希望有一种方法来设置默认状态。在您的情况下，处理程序KeyboardInterrupt将是要走的路。确保将伺服输出设置为处理程序中的标称值。

servo_middle_position = (servo_max - servo_min) / 2

try:
    while True:
        pwm.set_pwm(0, 0, servo_min)
        time.sleep(1)
        pwm.set_pwm(0, 0, servo_max)
        time.sleep(1)

except KeyboardInterrupt:
    print "User quit! Moving servo to middle position.'
    pwm.set_pwm(0, 0, servo_middle_position)

我猜你可能实际上没有使用 PWM 占空比确定位置的传统伺服 - 如果是这种情况，伺服将在到达所需位置后停止移动。您应该注意，伺服系统在运行时会产生一些热量。

于 2016-12-04T02:31:59.470 回答