Hello i have a small slight problem i have the seeedstudio v1.0 gsm shield on tmobile sim card some times it doesn't respond to me sending it a sms text message to turn on the led so if i shut it off and on a few times then it works but if i let it sit over night or something next day it doesn't work no led comes on or nothing the power key light is on i get blinking led showing it is powered up not sure what it is can someone help me? my sketch is below.
#include <SoftwareSerial.h>
char inchar; // Will hold the incoming character from the GSM shield
SoftwareSerial SIM900(7, 8);
int led1 = 13;
void setup()
{
Serial.begin(19200);
// set up the digital pins to control
pinMode(led1, OUTPUT);
digitalWrite(led1, LOW);
// wake up the GSM shield
SIM900power();
SIM900.begin(19200);
delay(20000); // give time to log on to network.
SIM900.print("AT+CMGF=1\r"); // set SMS mode to text
delay(100);
SIM900.print("AT+CNMI=2,2,0,0,0\r");
// blurt out contents of new SMS upon receipt to the GSM shield's serial out
delay(100);
Serial.println("Ready...");
}
void SIM900power()
// software equivalent of pressing the GSM shield "power" button
{
digitalWrite(9, HIGH);
delay(1000);
digitalWrite(9, LOW);
delay(7000);
}
void loop()
{
//If a character comes in from the cellular module...
if(SIM900.available() >0)
{
delay(10);
inchar=SIM900.read();
if (inchar=='a')
{
delay(10);
inchar=SIM900.read();
if (inchar=='0')
{
digitalWrite(led1, LOW);
}
else if (inchar=='1')
{
digitalWrite(led1, HIGH);
}
delay(10);
}
SIM900.println("AT+CMGD=1,4"); // delete all SMS
}
}
in the serial monitor says ready... that is all i get nothing else just sits there been on for over 24 hours and no response when i try to send a sms text to the gsm shield.
i have a 12v power adapter on the gsm shield and a 9v power adapter on the uno board. coming out of out of the pins i have D13 a led on there d12 led on there D11 and D10 4 leds total are on the breadboard.
I'm sorry you are correct wrong adapter the 12v adapter is on my monitor of my computer lol the shield is 5v 800ma only adapter i have besides the 9v one on the uno.
As I have said before you need a 5 volt, minimum 2 amp power supply for that shield. Some modem datasheets (granted not the SIM900) recommend a minimum of 3 amps.
I'm not going to pretend that changing the power supply will resolve the issue but if you don't comply with the basic requirements you are asking for intermittent problems.
i don't have a 5v 2amp power adapter just my cellphone haves that kind but wrong connector looks like i have to find one thank you i will check it out and try to see if that will help and keep update in there thanks again.
So when the SIM900 tries to draw 2 amps for an extended (but still brief) period for any reason, what do you think will happen to the voltage level? And what effect will this have on the normal operation of the device?
ok last night i found a 5v 2.5a power adapter i put the gsm shield and the uno still haves the 9v power adapter on it. i ran the same sketch and left it over night and it's still doing the same when i try to send the sms command nothing happen no response. i unplug the power and plug back back up waited for the network to kick in 30 to 40 seconds same thing.
blinking led to keep the sketch alive good idea i will remove the sim card and put it back in the cellphone but not sure i will see the messages because after the message is receive it gets deleted but i will see if the messages are coming in to the phone at least.