Arduino Forum > Products > Arduino GSM Shield > About the SIM900A module Alerts


I am using Arduno UNO with a GSM module (SIM900A). The module is powered by the 5V outputs of the UNO. The 5RX and 5TX pins are connected to pins 11 and 9 of the Arduino UNO board, I used the SoftwareSerial.h library. My code works fine I managed to send and receive my messages from the Arduino board without any problem. But when I power with an external power supply nothing gives more when I use another aptops to power nothing gives the device only works when connected to my machine. Please, I need help. I am running out of ideas.


SoftwareSerial mySerial(9, 11); // RX | TX int Chambre1 = 7; int strCumul void setup() { SIM900A.begin(9600); // opens serial port, sets data rate to 9600 bps pinMode(Chambre1, OUTPUT); SIM900A.println("AT+CNMI=2,2,0,0,0"); // Commande AT pour recevoir un SMS en direct SIM900A.println("AT+CMGF=1"); //Définit le module GSM en mode texte strCumul = "";

} void loop() { if (SIM900A.available()>0) { // Serial.println (strCumul.indexOf("ledOn")); // teste de la valeur retourner strCumul.concat(char(; //Lire et cumuler les caract delay(100);

// allumer la la chambre 1 if ((strCumul.indexOf("CH1_ON")>0)) { SIM900A.println("AT+CMGF=1"); //Définit le module GSM en mode texte delay(1000); // Delay of 1000 milli seconds or 1 second SIM900A.println("AT+CMGS=\"+237696414636\"\r"); // numéro delay(1000); SIM900A.println(Msg);//Le texte SMS que vous voulez envoyer delay(100); SIM900A.println((char)26);// Code ASCII de CTRL + Z delay(1000);

digitalWrite(Chambre1,HIGH); SIM900A.println("AT+CMGD=1,4"); // effacer le SMS de la Carte SIM strCumul = ""; } } }