Arduino Mega and GPS EM-411 problem

Other Hardware General Electronics
1

Hello!

I'm having exactly the same problem described in this topic: Arduino Forum

The only exception is that I'm using Arduino Mega instead of Uno.

Most curious thing is that it works pretty well with IDE 0023, but doesn't work at all with IDE 1.0.x!

Here are some examples of tests I did:

IDE 1.0.4, using GPS.available():

#include <SoftwareSerial.h>
SoftwareSerial GPS(2, 3);
int i = 0;
void setup() {
  Serial.begin(9600);
  GPS.begin(4800);
}

void loop() {
  if (i == 0) {
    Serial.println("here!");
    i = 1;
  }

  if (GPS.available()) { 
    Serial.write(GPS.read());
    Serial.println("here! o/");
    i = 0;
  }
}

and the output is (after 15 min waiting):

here!

IDE 1.0.4, without GPS.available():

#include <SoftwareSerial.h>
SoftwareSerial GPS(2, 3);
void setup() {
  Serial.begin(9600);
  GPS.begin(4800);
}

void loop() {
    Serial.write(GPS.read());
}

and the output is:

ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ

Finally with IDE 0023:

#include <SoftwareSerial.h>

SoftwareSerial GPS = SoftwareSerial(2,3);

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

void loop(){
  Serial.print(GPS.read(), BYTE);
}

and the great output is:

$GPRMC,144345.731,V,,,,,,,120313,,,N*49
$GPGGA,144346.742,,,,,0,00,,,M,0.0,M,,0000*57
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,144346.742,V,,,,,,,120313,,,N*4E
$GPGGA,144347.734,,,,,0,00,,,M,0.0,M,,0000*57
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,144347.734,V,,,,,,,120313,,,N*4E
$GPGGA,144348.731,,,,,0,00,,,M,0.0,M,,0000*5D
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,144348.731,V,,,,,,,120313,,,N*44
$GPGGA,144349.744,,,,,0,00,,,M,0.0,M,,0000*5E
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,144349.744,V,,,,,,,120313,,,N*47
$GPGGA,144350.732,,,,,0,00,,,M,0.0,M,,0000*57
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,1,1,00*79
$GPRMC,144350.732,V,,,,,,,120313,,,N*4E
$GPGGA,144351.732,,,,,0,00,,,M,0.0,M,,0000*56
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,144351.732,V,,,,,,,120313,,,N*4F
$GPGGA,144352.744,,,,,0,00,,,M,0.0,M,,0000*54
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPRMC,144352.744,V,,,,,,,120313,,,N*4D
$GPGGA,144353.732,,,,,0,00,,,M,0.0,M,,0000*54

I really thought that the problem could be the GPS module, until I find out that it works with IDE 0023.

Anyone could give me any ideas of what to do?

Thanks!
Alex

2

Every time I see "SoftwareSerial" I see another project that either doesn't work or works weirdly.

The Mega has four hardware serial ports. Try using one and see what happens...

3 
Every time I see "SoftwareSerial" I see another project that either doesn't work or works weirdly.

What should be better?

The Mega has four hardware serial ports. Try using one and see what happens...

You mean from 14 to 19?

4

Any ideas? I'm still not able to get it working with IDE 1.0.x!

5

Problem solved!

The problem really is the ports of Arduino Mega!

Thanks to this topic: Arduino Forum

Code at IDE 1.0.4:

#include <SoftwareSerial.h>

int rxPin = 10; // RX PIN
int txPin = 11; // TX TX

SoftwareSerial ss = SoftwareSerial(rxPin, txPin);

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

void loop() {
  if (ss.available()){
    char c = ss.read();
    Serial.print(c);
  }
}

And really thanks for everyone effort! :wink:

6

Serial1 Pin 19, RXD and Pin 18 TXD works just fine for me with either a Skylabs SKM53 @9600 baudOR a U-Blox-6 @ 4800 baud. Software Serial is for when you don't have spare UARTS... A Mega has 4, one used for the USB serial input leaves 3 free UARTS... Why use software to make a 'Software UART"..?

Bob

7

Docedison:
Why use software to make a 'Software UART"..?

Because GPS is just part of the project, not the project itself! :wink: