USB communication Arduino/Raspberry PI3 issue

Question

I'm trying to send data to my raspberry PI3 by USB.

Aim : One arduino (n°1) sends data to another by 433Mhz (virtualWire library on arduino) The other arduino(n°2) receives the data and transmits it to the raspberry by USB. This looks pretty simple but i spent several hours without succeed.

Here is my problem :

When i connect the arduino n°2 to the raspberry PI3 by USB, the arduino n°2 doesn't receive 433MHz data anymore.

Code used :

Arduino n°1 : sending data

*#include <VirtualWire.h>
#include <VirtualWire_Config.h>
#include <stdio.h>
#include <string.h>
int t=0;
char* controller="a";
void setup() {
  Serial.begin(9600);
  vw_set_ptt_inverted(true);
  vw_set_tx_pin(14);//Data pin 
  vw_setup(1200);// speed of data transfer Kbps
}
void loop(){
  vw_send((uint8_t *)controller, strlen(controller));
  vw_wait_tx(); // Wait until the whole message is gone
  Serial.println(controller);
  delay(2000);
}*

Arduino n°2 : receiving data from arduino n°1 and sending it to raspberry

*#include <VirtualWire.h>
    uint8_t buf[200];
    uint8_t buflen = 200;
String message;int i=0;
void setup()
{
  Serial.begin(9600);
    vw_set_ptt_inverted(true); // Required for DR3100
    vw_set_rx_pin(17);
    vw_setup(1200);  // Bits per sec
    vw_rx_start();       // Start the receiver PLL running
}
void loop()
{    
    if (vw_get_message(buf, &buflen)) // Non-blocking
    {
      message="";
      //Serial.println(char(buf[27]));
      for(i=0;i<buflen;i++){
              message+=char(buf[i]);
      }   
      Serial.println(message);
    }
}*

Raspberry : listening to USB (python code)

*import serial
ser=serial.Serial('/dev/ttyUSB0',9600)
while 1:
    print(ser.readline())*

Tests tried :

Communication between the two arduinos while arduino n°2 is not connected to raspberry => The data is received by arduino n°2 (checked by serial monitor)

Communication between arduino n°2 and raspberry => Sending a message which is not in the if (vw_get_message(buf, &buflen)){} works (checked in the shell of the raspberry)

Problem : The receiver 433Mhz of the arduino n°2 is not working when the arduino n°2 is connected to raspberry.

Can anyone help me?

Answer 1

I think decoding is the problem. Try this code.....

import serial
ser= serial.Serial('/dev/ttyUSB0', baudrate = 9600,timeout=0)
value = ser.readline().decode('ascii')
print('Value is : '.format(value))

Answer 2

I'm going to go out on a limb here and say it's not your Arduinos that's the problem. (It's not even your attitude about the problem that's the problem.)

Since you have checked the data communication over the Serial Monitor (test 1), it is evidently working when connected to some sort of computer. I would double-check your Python code on the RPi.

It's either not connecting to the Arduino correctly or it's not displaying the results correctly. I would write a super basic sketch for the Arduino just to test your serial connection to the RPi.

Well, that's all I have. I don't have a ready way to test your code, so.... Good luck!