Sim 800A + Arduino Uno + Idea Sim Card

Not Able to connect my Sim800 Module with Blynk, It is connected to Network But fails to connect with blynk.

#define BLYNK_PRINT Serial

// Select your modem:
//#define TINY_GSM_MODEM_SIM900
//#define TINY_GSM_MODEM_M590
//#define TINY_GSM_MODEM_A6
//#define TINY_GSM_MODEM_A7
//#define TINY_GSM_MODEM_BG96

// Default heartbeat interval for GSM is 60
// If you want override this value, uncomment and set this option:
//#define BLYNK_HEARTBEAT 30

#include <TinyGsmClient.h>
#include <BlynkSimpleTinyGSM.h>
#include <DHT.h>

#define DHTPIN 4          // D3
#define DHTTYPE DHT11     // DHT 11

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "kg-lc9Ahi-7rWbINp0NDARUZEOueTDU7";

// Your GPRS credentials
// Leave empty, if missing user or pass
char apn[]  = "internet";
char user[] = "";
char pass[] = "";

BlynkTimer timer;

// Hardware Serial on Mega, Leonardo, Micro
//#define SerialAT Serial1

// or Software Serial on Uno, Nano
#include <SoftwareSerial.h>
SoftwareSerial SerialAT(2,3); // RX, TX

TinyGsm modem(SerialAT);

void sendSensor()
  float h = dht.readHumidity();
  float t = dht.readTemperature(); // or dht.readTemperature(true) for Fahrenheit
  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
  // You can send any value at any time.
  // Please don't send more that 10 values per second.
  Blynk.virtualWrite(V5, t);
  Blynk.virtualWrite(V6, h);

void setup()
  // Debug console


  // Set GSM module baud rate

  // Restart takes quite some time
  // To skip it, call init() instead of restart()
  Serial.println("Initializing modem...");

  // Unlock your SIM card with a PIN

  Blynk.begin(auth, modem, apn, user, pass);
  // Setup a function to be called every second
  timer.setInterval(1000L, sendSensor);

void loop();;

Thanking you in anticipation

Please edit your post to wrap your code in triple backticks like this:

code goes here


First of all, you shoud set your baud rate to


Before (if it didn’t work), set baud rate to 9600 via AT commands directly to your SIM800 and save configurations. And ensure, that your poweing is correct: at least 3A is required.

1 Like

Can you also post your Serial output so we can see where it is failing?
(If @YetAnotherBlyn suggestion doesn’t work)