Reading Text from file and sending to GSM Module through Arduino

Question

I am trying to read some strings off a text file stored in my PC. My GSM Module is SIM900A I am using python to read the following line contained in the text file:

AT+CMGS=\"+9232xxxxxxxx\"\r

This line contains the AT command and the phone number to which I want to send the SMS.

The Python code is as follows:

import serial
import time

arduino = serial.Serial("COM3",9600,timeout = 5)
time.sleep(2)

i = 0

while(i<1):
  arduino.flush()
  text_file = open("Data.txt","r")
  line1 = text_file.readline()
  arduino.write(line1)
  time.sleep(1)
  i = i + 1
  exit()
text_file.close()

The Arduino code is as follows:

#include <SoftwareSerial.h>

SoftwareSerial mySerial(7, 8);
int counter = 0;
String msg1;
String numb = "AT+CMGS=\"+9232xxxxxxxx\"\r";

void setup() {
  mySerial.begin(9600);
  Serial.begin(9600);
  delay(100);
}

void loop() {
  while (!Serial.available()) {} // wait for data to arrive
  // serial read section
  while (Serial.available()) {
    if(Serial.available()>0) {
      msg1 = Serial.readString();
      if(counter<1) {
        SendMessage();
        counter++;
      }
    }
    delay(500);
  }
  if (mySerial.available()>0) Serial.write(mySerial.read());
}

void SendMessage() {
  mySerial.println("AT+CMGF=1");
  //Sets the GSM Module in Text Mode
  delay(1000);
  // Delay of 1000 milli seconds or 1 second
  mySerial.println(msg1);
  // Replace x with mobile number
  delay(1000);
  mySerial.println("Hello");
  // The SMS text you want to send
  delay(100);
  mySerial.println((char)26);
  // ASCII code of CTRL+Z
  delay(1000);
}

mySerial.println("AT+CMGS=\"+9232xxxxxxxx\"\r");
mySerial.println(numb);
mySerial.println(msg1);

If I use the first line, I get the message on my number. Similarly, for option 2, when I pass the string numb that I declared in the Arduino code above, I get the message.

However, for option 3, when I read the aforementioned string from the text file stored on the PC, I do not get a message. Can anyone please guide me what I am doing wrong here?

Answer 1

If the file contents is AT+CMGS=\"+9232xxxxxxxx\"\r as you posted, remove the escaping from the file. This should be the contents of the file:

AT+CMGS="+9232xxxxxxxx"

The quotes will be properly read without the attempted escaping. Then when you read the contents, if you need the \r just add it (assuming there's no new-line character at the end of the line):

line1 = text_file.readline() + '\r'