Serial.write() prints a variable twice

Question

I have this code:

#include <TinyGPS++.h>
#include <SoftwareSerial.h>


#define GPS_RX_PIN 2
#define GPS_TX_PIN 3

TinyGPSPlus gps;
SoftwareSerial ss(GPS_RX_PIN, GPS_TX_PIN);

void setup()
{
  Serial.begin(9600);
  ss.begin(4800); 
}

char clat[11];
char clng[11];

void loop()
{

        bool isGpsLocationValid = false;
        do
        {  
            while (ss.available()>0)
            {
                char c = byte(ss.read());
                if (gps.encode(c)) 
                {    
                    if (gps.location.isValid())
                    {
                        dtostrf(gps.location.lat(), 11, 6, clat);
                        dtostrf(gps.location.lng(), 11, 6, clng);
                        isGpsLocationValid = true;
                    }
                }   
             }
        } while (isGpsLocationValid == false);
        Serial.write(clat);
        Serial.println();
        Serial.write(clng);
}

Now when all is done, the clng value is printed twice in the serial monitor. The value i get is in this format:

27.275869  15.151013
  15.151013

As you can see, clng is printed twice. Any ideas why is that?

score 4 · Accepted Answer · answered Jun 20 '14 at 17:03

4

The width parameter to dtostrf() is the width of the resulting string NOT including the null terminator. So you are overflowing the array.

Change:

char clat[11];
char clng[11];

to

char clat[12];
char clng[12];

and it should work.

answered Jun 20 '14 at 17:03

Craig

2,120
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11

Serial.write() prints a variable twice

1 Answers1