按下按钮 5 秒时计数秒数

Question

所以我想使用 Python 在 Raspberry Pi 中创建一个系统，以通过电报通知和 LED 来判断开关按钮是否已“打开”5 秒，但我坚持让程序在开关按钮时计数 5 秒一直在。到目前为止，我的 Python 代码是：

import RPi.GPIO as io
from telethon import TelegramClient

api_id = ******
api_hash = "*********************"

client = TelegramClient('anon', api_id, api_hash)

io.setmode(io.BCM)
io.setwarnings(False)
io.setup(4, io.IN, pull_up_down=io.PUD_UP)
io.setup(24, io.OUT)

while True:
    if io.input(4) == 1:
        if time.time(5):
            io.output(24, 1)
            me = client.get_me()
            client.send_message('test', 'The switch button has been ON for 5 seconds')
        else:
            pass
    else:
        pass

如何修改程序，如果开关打开5秒，它会打开LED并发送通知？

Answer 1

time.time() 只返回自纪元时间以来的秒数。所以要知道是否已经过了 5 秒，你需要保存按下按钮的时间，然后继续检查它是否已经过了 5 秒。

这可以通过轮询或事件检测来完成。下面是如何通过事件检测来做到这一点，这是更可靠的方法：

button_pressed_time = None

def button_pressed(channel):
    global button_pressed_time 
    button_pressed_time = time.time()

def button_released(channel):
    global button_pressed_time 
    button_pressed_time = None
    #io.output(24, 1) --> you'll need this if you want to turn off the LED when the button is released

io.add_event_detect(4, io.RISING, callback=button_pressed)
io.add_event_detect(4, io.FALLING, callback=button_released)

while True:
    if button_pressed_time != None and time.time() - button_pressed_time >= 5:
        io.output(24, 1)
        me = client.get_me()
        client.send_message('test', 'The switch button has been ON for 5 seconds')
        button_pressed_time = None

有关轮询和事件检测的更多信息：https://sourceforge.net/p/raspberry-gpio-python/wiki/Inputs/

Answer 2

time.time() 不接受任何参数。调用时返回

the time in seconds since the epoch as a floating point number

您需要从开关打开的那一刻起计算 5 秒的经过时间。 您需要添加三个变量来实现此目的：

• 定时器：用于计算经过的时间，每次打开开关都需要重新设置。
• 开关的状态：它只有助于重置一次计时器（当开关打开时）。
• 消息的状态（无论是否发送）：这将有助于只发送一次消息。

最终的代码应该是这样的（重点是逻辑，我对树莓派上的python不太熟悉）：

import RPi.GPIO as io
from telethon import TelegramClient
import time

api_id = ******
api_hash = "*********************"

client = TelegramClient('anon', api_id, api_hash)

io.setmode(io.BCM)
io.setwarnings(False)
io.setup(4, io.IN, pull_up_down=io.PUD_UP)
io.setup(24, io.OUT)

led_on_start = 0 #initialise timer
led_on = False #initialise led state to "off"
message_sent = False #initialise message to "not sent"
while True:
    if io.input(4) == 1:
        if not led_on: #reset the timer when the switch is turned ON
            led_on_start = time.time() 
            led_on = True    
        if not message_sent and time.time() - led_on_start > 5:
            io.output(24, 1)
            me = client.get_me()
            client.send_message('test', 'The switch button has been ON for 5 seconds')
            message_sent = True
    else:
        if led_on: #reset your variables when the switch is turned OFF
            io.output(24, 0)
            message_sent = False
            led_on = False