Serial Communication Between Arduino and Raspberry pi3

Question

I am doing RF Communication between Arduino and Raspberry pi3. This is my Arduino code where connected with raspberry pi3 and it receives RF value from other RF Module.

#include <nRF24L01.h>
#include <RF24.h>
#include <RF24_config.h>
#include <SPI.h>
char msg[10];
RF24 radio(7,8);
const uint64_t pipe = 0x0a0c0a0c0aLL;
int lastmsg = 1;
String theMessage = "";
void setup(void){
  Serial.begin(9600);
  radio.begin();
  radio.openReadingPipe(1,pipe);
  radio.startListening();
}
void loop(void){
  if (radio.available()){
    bool done = false;  
      done = radio.read(msg, 1); 
      char theChar = msg[0];
      if (msg[0] != 2){
        theMessage.concat(theChar);
        }
      else {
       Serial.println(theMessage);
       theMessage= ""; 
      }
   }
}

and this is my Python code below

import serial
import time
# array
rf_array = ["RFID :"]

# Serial Communication
#port = "/dev/ttyACM2"
port = "/dev/ttyACM0"
# /dev/ttyACM2 is rfid Arduino
brate = 9600
arduino8 = serial.Serial(port, baudrate=brate, timeout=None)

while True:
    try:
        print("start")
        #arduino8 = serial.Serial(port, baudrate=brate, timeout=None)
        print("start1")
        data = arduino8.readline()
        print("start2")
        str = data[:-2].decode()
        str = str[:1]
        # str = int(str)
        rf_array.append(str)
        rf_array = list(set(rf_array))
        print(rf_array)


    except:
        print("no value")

It works when RF Module exists near my RF Module receiver but the problem is there is no Rf module near my RF Module receiver I figure out that data= arduino8.readline() is problem. Because there is no data from arduino8. So it doesn't go to next line. I know the problem, but I have no idea how to solve it. I really appreciate it if you help me. Thank you

@r_ahlskog can you tell me more detail?? I have to control it in Python — Daniel_Lee

r_ahlskog r_ahlskog · Accepted Answer · 2018-08-22T07:38:36

When using readline with Python Serial the documentation states

Be carefully when using readline(). Do specify a timeout when opening the serial port otherwise it could block forever if no newline character is received. Also note that readlines() only works with a timeout. readlines() depends on having a timeout and interprets that as EOF (end of file). It raises an exception if the port is not opened correctly.

This is what you are seeing so in your python code when you open the port

arduino8 = serial.Serial(port, baudrate=brate, timeout=None)

you should probably set the timeout to a reasonable value, like 1 second or more depending on your use, so that the library gives up waiting after a while.

Serial Communication Between Arduino and Raspberry pi3

1 Answers