我正在用python编写一个应用程序，该应用程序根据GPIO状态控制某些LED。在硬件上，我监听GPIO更改状态，然后发布到运行在树莓派上的MQTT服务器，以控制LED。 GPIO之一应使LED无限闪烁，直到状态再次改变以将其关闭为止，这正是汽车转向信号的工作原理。
因此，当GPIO变高时，我发布了有效负载为'on'的主题。然后，我设置一个全局变量
blinker_status = True
然后基本上说（伪代码）
while (blinker_status) { blink }
当我使用有效负载'off'发布到同一主题时，我设置了全局变量的值
blinker_status = False
我期望LED停止闪烁，但是不会。我不确定问题是否在于MQTT是否被阻止？
一旦我启动LED闪烁，也许是阻止了on_message()回调，并且它无法处理其他消息？我是否应该将所有订阅者客户端都隔离到各自的线程中，以便通过其各自的on_message()回调来处理发布到每个主题？
我有必要时可以提供的代码，但在这一点上，我一直试图理解为什么我的逻辑有缺陷。
下面是我的代码
import time
from neopixel import *
from threading import Thread
import paho.mqtt.client as mqtt
mqtt_client = None
# LED strip configuration:
LED_COUNT_LEFT = 150 # Number of LED pixels on the left strip.
LED_COUNT_RIGHT = 1 # Number of LED pixels on the right strip.
LED_FREQ_HZ = 800000 # LED signal frequency in hertz (usually 800khz)
LED_DMA = 10 # DMA channel to use for generating signal (try 10)
LED_BRIGHTNESS = 255 # Set to 0 for darkest and 255 for brightest
LED_INVERT = False # True to invert the signal (when using NPN transistor level shift)
LED_CHANNEL_LEFT = 0 # set to '1' for GPIOs 13, 19, 41, 45 or 53
LED_CHANNEL_RIGHT = 1
# NOTE: The WS2812B strip has red and green inverted, so red is actually (0, 255, 0) and green is (255, 0, 0)
left_blinker_status = False
right_blinker_status = False
blinker_status = False
# Create NeoPixel object with appropriate configuration.
# GPIO 18 is pin 12
left_strip = Adafruit_NeoPixel(LED_COUNT_LEFT, 18, LED_FREQ_HZ, LED_DMA, LED_INVERT, LED_BRIGHTNESS, LED_CHANNEL_LEFT)
# GPIO 13 is pin 33
right_strip = Adafruit_NeoPixel(LED_COUNT_RIGHT, 13, LED_FREQ_HZ, LED_DMA, LED_INVERT, LED_BRIGHTNESS,
LED_CHANNEL_RIGHT)
# Intialize the library (must be called once before other functions).
left_strip.begin()
right_strip.begin()
# MQTT functions
def start_mqtt():
global mqtt_client
try:
system_id = 'Kawasaki Ninja'
mqtt_client = mqtt.Client(client_id=system_id)
mqtt_client.disable_logger()
# Assign callback functions
mqtt_client.on_connect = on_connect
mqtt_client.on_message = on_message
mqtt_client.connect(host='192.168.1.23')
# Blocking call that processes network traffic, dispatches callbacks and
# handles reconnecting.
mqtt_client.loop_forever()
except Exception as ex:
print('Exception in start_mqtt()! exception: {}'.format(ex))
raise
# THe callback for when the client receives a CONNACK response from the server.
def on_connect(client, userdata, flags, rc):
print('Connected with result code ' + str(rc))
# Subscribing in on_connect() - if we lose connection and
# reconnect then subscriptions will be renewed.
client.subscribe('ninja/#') # The hash sign is wild-card
# The callback for when a PUBLISH message is received from the server.
def on_message(client, userdata, msg):
global blinker_status
global left_blinker_status
global right_blinker_status
print('{} {}'.format(msg.topic, str(msg.payload)))
# Handle the brake topic
if msg.topic == 'ninja/brake':
if msg.payload == 'on':
# BRAKE ON
if not left_blinker_status:
solidColor(left_strip, Color(0, 255, 0))
if not right_blinker_status:
solidColor(right_strip, Color(0, 255, 0))
elif msg.payload == 'off':
# BRAKE OFF
if not left_blinker_status:
solidColor(left_strip, Color(255, 255, 255))
if not right_blinker_status:
solidColor(right_strip, Color(255, 255, 255))
# Handle the left turn signal topic
elif msg.topic == 'ninja/left_turn_signal':
# Left turn signal on
if msg.payload == 'on':
blinker_status = True
left_blinker_status = True
while left_blinker_status:
blinker(blinker_status, left_strip)
# Left turn signal off
elif msg.payload == 'off':
blinker_status = False
left_blinker_status = False
solidColor(left_strip, Color(255, 255, 255))
# Handle the right turn signal topic
elif msg.topic == 'ninja/right_turn_signal':
# Right turn signal on
if msg.payload == 'on':
blinker_status = True
right_blinker_status = True
while right_blinker_status:
blinker(blinker_status, right_strip)
# Right turn signal off
elif msg.payload == "off":
blinker_status = False
right_blinker_status = False
solidColor(right_strip, Color(255, 255, 255))
# Handle the party time topic
elif msg.topic == 'ninja/party_time':
# Party on
if msg.payload == 'on':
colorWipe(left_strip, Color(0, 255, 0)) # Red
elif msg.payload == 'white':
solidColor(left_strip, Color(255, 255, 255))
elif msg.payload == 'wipe':
colorWipe(left_strip, Color(0, 255, 0)) # Red
elif msg.payload == 'off':
solidColor(left_strip, Color(0, 0, 0))
# Neopixel functions
# Define functions which animate LEDs in various ways.
def colorWipe(strip, color, wait_ms=50):
"""Wipe color across display a pixel at a time."""
for i in range(strip.numPixels()):
strip.setPixelColor(i, color)
strip.show()
time.sleep(wait_ms / 1000.0)
def solidColor(strip, color):
for i in range(strip.numPixels()):
strip.setPixelColor(i, color)
strip.show()
def blinker(blinker_status, strip):
while blinker_status:
solidColor(strip, Color(65, 100, 0))
time.sleep(0.5)
solidColor(strip, Color(0, 0, 0))
time.sleep(0.5)
try:
while True:
mqtt_thread = Thread(target=start_mqtt, args=())
mqtt_thread.isDaemon()
mqtt_thread.start()
except KeyboardInterrupt:
exit()
on_message回调在MQTT客户端的网络线程上运行，如果您阻止该线程，您将无法再发送或接收任何消息。
您不应在此（或任何客户端回调）中进行任何阻塞或长时间运行的操作，您应该在状态机中设置标志并使用这些更改来控制其他线程。