Arduino Uno and MKR GSM 1400

Hi, I have a project that need to send sms notification when there is input signal to my Arduino Uno. I have done all my code all on Arduino Uno. Just need to call sms function as an output.

How do i link up with my MKR GSM 1400? Do I need to connect via TX RX for both micro-controller? Using TX RX how output to be send to MKR GSM 1400 so it will send sms?

Below is my testing with MKR GSM 1400:

// Include the GSM library
#include <MKRGSM.h>
#define PINNUMBER ""

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

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

  Serial.println("SMS Messages Sender");

  // connection state
  bool connected = false;

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

  Serial.println("GSM initialized");
  char txtMsg[200] = "Test";
  char remoteNumber[20] = "97702265";

void loop() {


Are you asking how to link the Uno to the MKR GSM 1400?

Yes correct

You need to be aware that the 5 V logic levels of the Uno are not safe for the MKR GSM 1400 (which uses 3.3 V). For this reason, you should use a level shifter on the line to the MKR GSM 1400's RX pin.

Yeah Arduino UNO & MKR GSM 1400 works on different voltage level so you need to use a Logic Level Shifter between TX & RX Pins. Make a search for CD4050, I have used it for XBee (operates on 3.3V), worked perfectly.