GSM SIM 900 not work with Arduino UNO

#define BLYNK_PRINT Serial

// Select your modem:
//#define TINY_GSM_MODEM_SIM800
//#define TINY_GSM_MODEM_M590
//#define TINY_GSM_MODEM_A6

// 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 <BlynkSimpleSIM800.h>

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

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

// 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 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);

void loop()

As a temporary solution, until dev will take care of it, I may suggest downgrading library to 0.20, which I can confirm as working with SIM900. You may do so either in library manager or going straight to TinyGSM releases and download from there.

I try many times but it didnt work but before in version 5.01 it was working perfectly

But the error points to TinyGSM library, not explicitly Blynk. Then just downgrade this one, not the whole package.

I try you use sim_800 and it the code work but when i use sim_900 cant work and there is exit error 1 :confounded:

But still on TinyGSM 0.3.2? That is because there is one (at least :wink:) small error in 0.3.2, ie the rsp variable is not declared. That is very easy to correct, but it needs to “mess” within lib files. The error is precisely pointed in IDE… If you wish, you can add manually int before the rsp=... and it should go (at least past that line). But I suggested you TWICE already to fallback to 0.2, which was tested and confirmed working with SIM900.

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What do you mean 0.2 ? Also where i can find rsp to delarce

Here’s TinyGSM 0.2.0:
Replace existing with the one from this link.

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TinyGSM v0.3.3 is out and should work with SIM900 again (should be also available soon in the Library Manager)