"Problem Reading Temperature from DHT11 Sensor via RS485 Between Raspberry Pi 4 and Raspberry Pi Pic

Rıdvan Ç. (rdvan) 2023-09-16 12:53 #7498208

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I want to read the temperature data from the DHT11 sensor connected to the Pico using RS485 between Raspberry Pi 4 and Raspberry Pi Pico. I use the following code for this, but when I use it like this, I can send data from Raspberry Pi without any problems. However, when I send data from Raspberry Pi Pico, if I assume the temperature is 25, sometimes I can read this value from Raspberry Pi and sometimes I can't. I tried to adjust the correct time with Time.sleep() but I couldn't succeed. How can I solve this?

Raspberry Pi Code

import serial

import time

RS485 = serial.Serial('/dev/serial0', baudrate=9600, timeout=1)

def send_data(data):

    ser = serial.Serial('/dev/serial0', baudrate=9600, timeout=1)

    ser.write(data.encode())

    print("data sent")

temperature = 0

while True:

    data_to_send = "xtemperature"

    time.sleep(1)

    send_data(data_to_send)

    time.sleep(1)

    while True:

        received_data = RS485.readline().rstrip()

        received_data = received_data.decode('utf-8')

        print(received_data)

        time.sleep(1)

        received_value = int(received_data)  

        if 0 <= received_value <= 70:

            temperature=received_value

            break

    break

print("TEMPERATURE : ",temperature)

Raspberry Pi Pico Code

from machine import Pin

import time

from dht import  DHT11

uart_tx = machine.Pin(4)  # TX pin: GPIO 0

uart_rx = machine.Pin(5)  # RX pin: GPIO 1

uart = machine.UART(1, baudrate=9600, tx=uart_tx, rx=uart_rx)

def response():

    received_data = uart.read()

    try:

        received_string = received_data.decode('utf-8').strip()

        print("DATA :")

        print(received_string)

        if received_string:

            if received_string[0] == 'x':

                pin = Pin(15,Pin.IN,Pin.PULL_UP)

                d = DHT11(Pin(15))

                d.measure()

                T = d.temperature()

                while x<150:

                    T=d.temperature()

                    send_data = str(T)

                    data = (send_data + "\r\n")

                    time.sleep(1)

                    uart.write(data.encode('utf-8'))

                    print("data sent")

                    print(data)

                return received_string

    except UnicodeError:

        pass

    return ""

while True:

    if uart.any():

        incoming_data = response()

        print(incoming_data)

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