Send/Receive SMS with STM32F103C8 and SIM800C GSM Module
Components Required
- STM32F103C8 Cortex-M3 Microcontroller
- GSM Module (SIM800C is used in the tutorial)
- 16x2 LCD Display
- Push Buttons (2)
- 10k Potentiometer
- Breadboard
- Connecting Wires
What is SIM800C GSM Module?
Circuit Diagram
Circuit connections between STM32F103C8 & GSM SIM800C
| STM32F103C8 | GSM SIM800C |
| PA9 (TX) | RX |
| PA10 (RX) | TX |
| GND | GND |
#include <LiquidCrystal.h> //Library for LCD display
const int rs = PB11, en = PB10, d4 = PB0, d5 = PB1, d6 = PC13, d7 = PC14; //Pins that are connected between LCD and STM32
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
int receive = 0;
void setup()
{
lcd.begin(16,2); //LCD set at 16x2 mode
pinMode(PA0,INPUT); //Push buttons as INPUT pins
pinMode(PA1,INPUT);
lcd.print("STM32 WITH GSM"); //Display Welcome message
lcd.setCursor(0,1);
lcd.print("SIM800C");
Serial1.begin(9600); // Setting the baud rate of GSM Module
delay(1000);
lcd.clear();
}
void loop()
{
lcd.clear();
lcd.setCursor(0,0);
lcd.print("S to Send sms");
lcd.setCursor(0,1);
lcd.print("R to Receive sms");
delay(100);
int a = digitalRead(PA0); //Read status of the push buttons
int b = digitalRead(PA1);
if (a == 1) // Depeding upon which push button is pressed the respected function is called
{
SendMessage();
}
else if( b == 1)
{
RecieveMessage();
}
}
void SendMessage() //Function to Send Message
{
lcd.clear();
lcd.print("Sending sms");
delay(1000);
Serial1.println("AT+CMGF=1"); //Sets the GSM Module in Text Mode
delay(1000);
Serial1.println("AT+CMGS=\"+91XXXXXXXXXX\"\r"); // Replace x with mobile number
delay(1000);
Serial1.println("Hi Circuit Digest from GSM Module"); // The SMS text you want to send
delay(100);
Serial1.println((char)26);// ASCII code of CTRL+Z
delay(1000);
lcd.clear();
lcd.print("SMS SENT");
delay(1000);
}
void RecieveMessage() //Function to Receive Message
{
lcd.clear();
lcd.print("Receiving sms");
Serial1.println("AT+CNMI=2,2,0,0,0"); // AT Command to recieve a live SMS
delay(1000);
while(1)
{
if(Serial1.available())
{
do
{
while ( !Serial1.available() );
} while ( '"' != Serial1.read() );
do
{
while ( !Serial1.available() );
} while ( '"' != Serial1.read() );
do
{
while ( !Serial1.available() );
} while ( '"' != Serial1.read() );
do
{
while ( !Serial1.available() );
} while ( '"' != Serial1.read() );
do
{
while ( !Serial1.available() );
} while ( '"' != Serial1.read() );
do
{
while ( !Serial1.available() );
} while ( '"' != Serial1.read() );
while ( !Serial1.available() );
receive = Serial1.read();
while ( !Serial1.available() );
receive = Serial1.read();
lcd.clear();
while(1)
{
while ( !Serial1.available() );
receive = Serial1.read();
if ( receive == '\r' )
break;
else
lcd.write(receive);
}
}
}
}