Connecting gsm and gps modules to arduino

[bobdxcool]

Guys, I tried connecting gsm and gps modules (ttl pins) to tx n rx of arduino. It did not work.

I am totally confused.

This is what I did.

1. I soldered two wires from tx and rx pins of my gps and gsm boards. (this is because my boards had max 232 ic's on the board and had a rs 232 output, so I soldered 2 wires at the point where the rx and tx pins of gsm/ gps are connected to max 232)

2. I connected the tx pin of gsm to rx pin (pin 0) of arduino uno and rx of gsm to tx (pin1) of
arduino. I did this for both gsm and gps modules separately.

3. I just made 2 connections b/w arduino and gsm/gps. No other connections. I powered both the modules using 12v ac/dc adapter connected to the power pin provided on the board. I did not connect the grounds of gsm/gps to arduino or to each other.

GSM module used- sim300
GPS module used- Holux GR-87- baud-4800


The arduino tx and rx pins give 5v, whereas the gps and gsm modules (not boards) rx and tx pins give voltage under 4v (3.3v, 2.9v) .

Is this the problem?

Please help.


This is code I used for testing gsm-sending message to a number

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#include <NewSoftSerial.h>
NewSoftSerial cell(0,1); 
char mobilenumber[] = "xxxxxxxxx";  // Replace xxxxxxxx with the recipient's mobile number
void setup()
{  //Initialize serial ports for communication.
cell.begin(4800);
delay(3500); // give the GSM module time to initialise, locate network etc.
// this delay time varies. Use example 26.1 sketch to measure the amount
// of time from board reset to SIND: 4, then add five seconds just in case
}
void loop()
{
cell.println("AT+CMGF=1"); // set SMS mode to text
cell.print("AT+CMGS=");  // now send message...
cell.print(34,BYTE); // ASCII equivalent of "
cell.print(mobilenumber);
cell.println(34,BYTE);  // ASCII equivalent of "
delay(500); // give the module some thinking time
cell.print("They call me the count... because I like to count! Ah ha ha ha");   // our message to send
cell.println(26,BYTE);  // ASCII equivalent of Ctrl-Z
delay(15000); // the SMS module needs time to return to OK status
do // You don't want to send out multiple SMSs.... or do you?
{
delay(1);
}
while (1>0);
}

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Code for testing gps

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#include <NewSoftSerial.h>
 
#include <TinyGPS.h>
 
/* This sample code demonstrates the normal use of a TinyGPS object.
   It requires the use of NewSoftSerial, and assumes that you have a
   4800-baud serial GPS device hooked up on pins 0(rx) and 1(tx).
*/
 
TinyGPS gps;
NewSoftSerial nss(0, 1);
 
static void gpsdump(TinyGPS &gps);
static bool feedgps();
static void print_float(float val, float invalid, int len, int prec);
static void print_int(unsigned long val, unsigned long invalid, int len);
static void print_date(TinyGPS &gps);
static void print_str(const char *str, int len);
 
void setup()
{
  Serial.begin(115200);
  nss.begin(4800);
  
  Serial.print("Testing TinyGPS library v. "); Serial.println(TinyGPS::library_version());
  Serial.println("by Mikal Hart");
  Serial.println();
  Serial.print("Sizeof(gpsobject) = "); Serial.println(sizeof(TinyGPS));
  Serial.println();
  Serial.println("Sats HDOP Latitude Longitude Fix  Date       Time       Date Alt     Course Speed Card  Distance Course Card  Chars Sentences Checksum");
  Serial.println("          (deg)    (deg)     Age                        Age  (m)     --- from GPS ----  ---- to London  ----  RX    RX        Fail");
  Serial.println("--------------------------------------------------------------------------------------------------------------------------------------");
}
 
void loop()
{
  bool newdata = false;
  unsigned long start = millis();
  
  // Every second we print an update
  while (millis() - start < 1000)
  {
    if (feedgps())
      newdata = true;
  }
  
  gpsdump(gps);
}
 
static void gpsdump(TinyGPS &gps)
{
  float flat, flon;
  unsigned long age, date, time, chars = 0;
  unsigned short sentences = 0, failed = 0;
  static const float LONDON_LAT = 51.508131, LONDON_LON = -0.128002;
  
  print_int(gps.satellites(), TinyGPS::GPS_INVALID_SATELLITES, 5);
  print_int(gps.hdop(), TinyGPS::GPS_INVALID_HDOP, 5);
  gps.f_get_position(&flat, &flon, &age);
  print_float(flat, TinyGPS::GPS_INVALID_F_ANGLE, 9, 5);
  print_float(flon, TinyGPS::GPS_INVALID_F_ANGLE, 10, 5);
  print_int(age, TinyGPS::GPS_INVALID_AGE, 5);
 
  print_date(gps);
 
  print_float(gps.f_altitude(), TinyGPS::GPS_INVALID_F_ALTITUDE, 8, 2);
  print_float(gps.f_course(), TinyGPS::GPS_INVALID_F_ANGLE, 7, 2);
  print_float(gps.f_speed_kmph(), TinyGPS::GPS_INVALID_F_SPEED, 6, 2);
  print_str(gps.f_course() == TinyGPS::GPS_INVALID_F_ANGLE ? "*** " : TinyGPS::cardinal(gps.f_course()), 6);
  print_int(flat == TinyGPS::GPS_INVALID_F_ANGLE ? 0UL : (unsigned long)TinyGPS::distance_between(flat, flon, LONDON_LAT, LONDON_LON) / 1000, 0xFFFFFFFF, 9);
  print_float(flat == TinyGPS::GPS_INVALID_F_ANGLE ? 0.0 : TinyGPS::course_to(flat, flon, 51.508131, -0.128002), TinyGPS::GPS_INVALID_F_ANGLE, 7, 2);
  print_str(flat == TinyGPS::GPS_INVALID_F_ANGLE ? "*** " : TinyGPS::cardinal(TinyGPS::course_to(flat, flon, LONDON_LAT, LONDON_LON)), 6);
 
  gps.stats(&chars, &sentences, &failed);
  print_int(chars, 0xFFFFFFFF, 6);
  print_int(sentences, 0xFFFFFFFF, 10);
  print_int(failed, 0xFFFFFFFF, 9);
  Serial.println();
}
 
static void print_int(unsigned long val, unsigned long invalid, int len)
{
  char sz[32];
  if (val == invalid)
    strcpy(sz, "*******");
  else
    sprintf(sz, "%ld", val);
  sz[len] = 0;
  for (int i=strlen(sz); i<len; ++i)
    sz[i] = ' ';
  if (len > 0) 
    sz[len-1] = ' ';
  Serial.print(sz);
  feedgps();
}
 
static void print_float(float val, float invalid, int len, int prec)
{
  char sz[32];
  if (val == invalid)
  {
    strcpy(sz, "*******");
    sz[len] = 0;
        if (len > 0) 
          sz[len-1] = ' ';
    for (int i=7; i<len; ++i)
        sz[i] = ' ';
    Serial.print(sz);
  }
  else
  {
    Serial.print(val, prec);
    int vi = abs((int)val);
    int flen = prec + (val < 0.0 ? 2 : 1);
    flen += vi >= 1000 ? 4 : vi >= 100 ? 3 : vi >= 10 ? 2 : 1;
    for (int i=flen; i<len; ++i)
      Serial.print(" ");
  }
  feedgps();
}
 
static void print_date(TinyGPS &gps)
{
  int year;
  byte month, day, hour, minute, second, hundredths;
  unsigned long age;
  gps.*****_datetime(&year, &month, &day, &hour, &minute, &second, &hundredths, &age);
  if (age == TinyGPS::GPS_INVALID_AGE)
    Serial.print("*******    *******    ");
  else
  {
    char sz[32];
    sprintf(sz, "%02d/%02d/%02d %02d:%02d:%02d   ",
        month, day, year, hour, minute, second);
    Serial.print(sz);
  }
  print_int(age, TinyGPS::GPS_INVALID_AGE, 5);
  feedgps();
}
 
static void print_str(const char *str, int len)
{
  int slen = strlen(str);
  for (int i=0; i<len; ++i)
    Serial.print(i<slen ? str[i] : ' ');
  feedgps();
}
 
static bool feedgps()
{
  while (nss.available())
  {
    if (gps.encode(nss.read()))
      return true;
  }
  return false;
}

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This code gave number of received characters, but did not show any latitude and longitude.

- - - Updated - - -

These are pictures of my gps and gsm modules.





GPS module



GSM module

 

[apolama]

the GSM module responses after getting \r\n

I think you need to read View attachment doc8016[1].pdf

 

[electronicsbasecom]

Try first to connect modem to PC and test some commands via Terminal program. Than check if your board sends AT commands correctly. Than connect board and modem and try to monitor communication between.