Question

我正在尝试使用连接到Arduino的HC12实现无线土壤湿度传感器，以发送信号（值：0-100％），然后激活连接到树莓派3的继电器，具体取决于百分比（例如：打开20％，关闭90％）。我弄清楚了如何发送值，并且能够在pi上看到它们，但是我无法激活继电器。请帮忙。

这是我正在使用的代码：

import RPi.GPIO as GPIO 
import smtplib 
import time
from time import sleep 
import serial

GPIO.setmode(GPIO.BCM)  # Set our GPIO numbering to BCM
relay_pin = 16
GPIO.setup(relay_pin, GPIO.OUT)
GPIO.output(relay_pin, 1) 

ser = serial.Serial ("/dev/ttyS0",9600)   #Open port with baud rate

try:
    while True:
        received_data = ser.read()              #read serial port
        data_left = ser.inWaiting()             
        received_data += ser.read(data_left)
        print (received_data)                   #print received data
        ser.write(received_data)                #transmit data serially

        if received_data <= '20':
            GPIO.output(relay_pin, 0)
        elif received_data >= '90':
            GPIO.output(relay_pin, 1)

except KeyboardInterrupt:
    pass
GPIO.cleanup()

Answer 1

我认为，问题出在语句if中。

if received_data <= '20':
    GPIO.output(relay_pin, 0)
elif received_data >= '90':
    GPIO.output(relay_pin, 1)

'20'是不是数字的字符串。
尝试删除引号，如下所示：

if received_data <= 20:
    GPIO.output(relay_pin, 0)
elif received_data >= 90:
    GPIO.output(relay_pin, 1)

Answer 2

我仍然在使用代码方面遇到麻烦，并且将代码更改为：如果int（received_data）<= 20，则会出现错误消息。这是修改后的代码：

import RPi.GPIO as GPIO 
import smtplib 
import time
from time import sleep 
import serial

GPIO.setmode(GPIO.BCM)  # Set our GPIO numbering to BCM
relay_pin = 16
GPIO.setup(relay_pin, GPIO.OUT)
GPIO.output(relay_pin, GPIO.HIGH) 

ser = serial.Serial ("/dev/ttyS0",9600)  

try:
    while True:
        received_data = ser.read()   #read serial port
        data_left = ser.inWaiting()             
        received_data += ser.read(data_left)
        print (received_data)     #print received data
        ser.write(received_data) #transmit data serially

        if int(received_data) <= 20:
            GPIO.output(relay_pin, GPIO.HIGH)
        elif int(received_data) >= 90:
            GPIO.output(relay_pin, GPIO.LOW)
        else:
            GPIO.output(relay_pin, GPIO.LOW)

except KeyboardInterrupt:
    pass
GPIO.cleanup()

但是，当我删除“ if int（received_data）<= 20”并将代码保留为：

import RPi.GPIO as GPIO 
import smtplib 
import time
from time import sleep 
import serial

GPIO.setmode(GPIO.BCM)  # Set our GPIO numbering to BCM
relay_pin = 16
GPIO.setup(relay_pin, GPIO.OUT)
GPIO.output(relay_pin, GPIO.HIGH) 

ser = serial.Serial ("/dev/ttyS0",9600)  

try:
    while True:
        received_data = ser.read()   #read serial port
        data_left = ser.inWaiting()             
        received_data += ser.read(data_left)
        print (received_data)     #print received data
        ser.write(received_data) #transmit data serially

        if received_data <= 20:
            GPIO.output(relay_pin, GPIO.HIGH)
        elif received_data >= 90:
            GPIO.output(relay_pin, GPIO.LOW)
        else:
            GPIO.output(relay_pin, GPIO.LOW)

except KeyboardInterrupt:
    pass
GPIO.cleanup()

继电器打开，但不响应从Arduino和土壤湿度传感器接收到的串行数据。我在想也许可以定义来自Arduino的串行数据，比如说：在湿度为20％时打开继电器，在土壤湿度为90％时关闭继电器，因此将20％的值定义为“ 1”或GPIO.HIGH打开继电器，反之亦然，但是我不知道该如何实现。有什么建议吗？

Arduino通过HC12将继电器控制到树莓派

2 个答案: