SIM808 is all in one module with GSM , GPRS,GPS & BLUETOOTH.SIM808 is advanced compared to SIM908.
SIM808 has GNSS receiver which enables easy GPS FIX.
In this post we explore how to parse GPS data ( without using TNYGPS library) & send it through inbuilt GSM
SIM 808 has 2 antenna sockets one for GSM & other for GPS. A stub antenna is used for GSM & a magnetic external patch antenna is used for GPS.
Do not interchange these 2 antennae. The antenna socket nearest to SIM808 chip is for GPS.
Connection between Arduino UNO & SIM808 is simple.
Gnd to Gnd
Tx of SIM808 to Rx of Arduino (soft serial digital pin 7)
Rx of SIM808 toTx of Arduino (soft serial digital pin 8)
A separate power adapter of 12v 2amp is required for SIM808 board.
Insert valid SIM on to the slot at the back of SIM808 board
Power on & notice the NETWORK LED .It blinks fast initially & when it gets network it blinks slowly ,once per second.
We’ll use a serial to usb cable to monitor SIM808 serial port. We can also test AT commands through this port ,before uploading Arduino code.
Connect the cable to PC & note the COM port allotted under Device Manager .
Another COM port is allotted to Arduino board.Note this also.
Before uploading code on to Arduino , let us check the AT commands.
For this open a PUTTY Terminal & select SERIAL.
Feed in the COM port of the USB-RS232 cable &baud rate as 9600. & click open.
Type in AT ,the SIM808 module responds with OK.
ATD is the command to dial a number
AT+CMGF=1 , AT+CMGS=”phone no.” are for sending SMS.
All GSM related commands are similar to that of SIM800 or SIM900.
Some cases of empty SMS delivery is reported .i.e you receive SMS on mobile but has got no message.
To solve this problem set the following parameter.
AT+CSMP=17,167,0,0
This has to be done before you set the module to Text mode using AT_CMGF=1
GPS related AT Commands are similar to that of SIM 908.
AT+CGPSPWR=1 sets the GPS engine ON
AT+CGPSRST=0 gives a COLD RESTART to GPS
AT+CGSINF=0 returns a single NMEA sentence of GPS.
AT+CGPSSTATUS? returns the Status of GPS whether it has got FIX or not.
If GPS has not received FIX , the NMEA sentence will read all 0 s
Relocate the GPS antenna & wait for some time to get a FIX. If the GPS antenna faces open SKY you get a FIX within seconds.
Once GPS gets a FIX , AT+CGPSINF=0 returns a valid NMEA sentence.
AT+CGPSINF=32 returns a single GPRMC sentence
Now let us see the SIM808 specific GPS commands
SIM808 has inbuilt GNSS receiver
AT+CGNSPWR=1 turns on the GNSS power
AT+CGNSSEQ=”RMC” parses the NMEA sentence related to GPRMC
Now issuing the command AT_CGNSINF returns a valid NMEA GPRMC sentence
Now let us upload the code that parses RMC data &sends SMS with google maps link
Arduino code Download :
http://www.alselectro.com/files/SIM808.zip
—————————————————
#include <SoftwareSerial.h>
SoftwareSerial sim808(7,8);
char phone_no[] = “xxxxxxx”; // replace with your phone no.
String data[5];
#define DEBUG true
String state,timegps,latitude,longitude;
void setup() {
sim808.begin(9600);
Serial.begin(9600);
delay(50);
sim808.print(“AT+CSMP=17,167,0,0”); // set this parameter if empty SMS received
delay(100);
sim808.print(“AT+CMGF=1\r”);
delay(400);
sendData(“AT+CGNSPWR=1”,1000,DEBUG);
delay(50);
sendData(“AT+CGNSSEQ=RMC”,1000,DEBUG);
delay(150);
}
void loop() {
sendTabData(“AT+CGNSINF”,1000,DEBUG);
if (state !=0) {
Serial.println(“State :”+state);
Serial.println(“Time :”+timegps);
Serial.println(“Latitude :”+latitude);
Serial.println(“Longitude :”+longitude);
sim808.print(“AT+CMGS=\””);
sim808.print(phone_no);
sim808.println(“\””);
delay(300);
sim808.print(“http://maps.google.com/maps?q=loc:”);
sim808.print(latitude);
sim808.print(“,”);
sim808.print (longitude);
delay(200);
sim808.println((char)26); // End AT command with a ^Z, ASCII code 26
delay(200);
sim808.println();
delay(20000);
sim808.flush();
} else {
Serial.println(“GPS Initializing…”);
}
}
void sendTabData(String command , const int timeout , boolean debug){
sim808.println(command);
long int time = millis();
int i = 0;
while((time+timeout) > millis()){
while(sim808.available()){
char c = sim808.read();
if (c != ‘,’) {
data[i] +=c;
delay(100);
} else {
i++;
}
if (i == 5) {
delay(100);
goto exitL;
}
}
}exitL:
if (debug) {
state = data[1];
timegps = data[2];
latitude = data[3];
longitude =data[4];
}
}
String sendData (String command , const int timeout ,boolean debug){
String response = “”;
sim808.println(command);
long int time = millis();
int i = 0;
while ( (time+timeout ) > millis()){
while (sim808.available()){
char c = sim808.read();
response +=c;
}
}
if (debug) {
Serial.print(response);
}
return response;
}
——————————————————-
Following is the serial port monitor screenshot.
Once the command AT+CGNSINF is issued ,it returns a valid RMC sentence.
The latitude,longitude is then parsed
SMS is then sent with parsed data appended to google maps link.
Pleae note Code is written to send SMS every 20 secs.
VIDEO :
alselectro 