Arduino GSM GPS Shield doesn't do the GSM_READY check

Question

Before you mark this question as duplicate, please note that I have already tried this, this & this

I bought an Arduino UNO R3 & a SIM808 GSM/GPS shield recently. The RX of the Shield is connected to Pin 11 of Arduino, TX to Pin 10 with both the GNDs connected to each other. I have connected my Arduino to my computer with the USB & the shield is connected to an external power supply with a 12V Adapter. Additionally, I have connected the 3.3V of the Arduino to Vcc of the shield.

Following is the sketch I have used:

// Include the GSM library
#include <GSM.h>

#define PINNUMBER ""

// initialize the library instance
GSM gsmAccess;
GSM_SMS sms;

void setup() {
  // initialize serial communications and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  Serial.println("SMS Messages Sender");

  // connection state
  boolean notConnected = true;

  // Start GSM shield
  // If your SIM has PIN, pass it as a parameter of begin() in quotes
  while (notConnected) {
    if (gsmAccess.begin(PINNUMBER) == GSM_READY) {
      notConnected = false;
    } else {
      Serial.println("Not connected");
      delay(1000);
    }
  }

  Serial.println("GSM initialized");
}

void loop() {

  Serial.print("Enter a mobile number: ");
  char remoteNum[20];  // telephone number to send sms
  readSerial(remoteNum);
  Serial.println(remoteNum);

  // sms text
  Serial.print("Now, enter SMS content: ");
  char txtMsg[200];
  readSerial(txtMsg);
  Serial.println("SENDING");
  Serial.println();
  Serial.println("Message:");
  Serial.println(txtMsg);

  // send the message
  sms.beginSMS(remoteNum);
  sms.print(txtMsg);
  sms.endSMS();
  Serial.println("\nCOMPLETE!\n");
}

/*
  Read input serial
 */
int readSerial(char result[]) {
  int i = 0;
  while (1) {
    while (Serial.available() > 0) {
      char inChar = Serial.read();
      if (inChar == '\n') {
        result[i] = '\0';
        Serial.flush();
        return 0;
      }
      if (inChar != '\r') {
        result[i] = inChar;
        i++;
      }
    }
  }
}

Problem here is same as that mentioned in those linked posts.

The condition if (gsmAccess.begin(PINNUMBER) == GSM_READY) never gets executed. Neither does the else part execute.

Serial monitor never goes past SMS Messages Sender.

Please note that I am using AirTel India, I have a fully activated Data Plan & the PIN Number has been changed to 0000.

Would really appreciate if someone could suggest something helpful.

Thanks for your time!!

RickJansen RickJansen · Accepted Answer · 2016-05-11T19:55:19

You cannot power a GSM module from the 3.3V of Arduino! a GSM needs peak currents of 3A (yes, Amps, not milli-amperes). You really need a LiPo battery to power the GSM. You could power a 3V Arduino from the same LiPo battery, actually, if you need a mobile solution, but not the other way around.

Arduino GSM GPS Shield doesn't do the GSM_READY check

3 Answers