Mike Cochrane

May 23, 2011

I recently replaced my Holux GPSlim236 with a Holux M-1000, so I decided to work out how to connect the 236 to an Arduino.

Initially I pulled it apart and found the 7 test points on the left of the board. These turned out to be a serial interface, from top to bottom:

1. ?
2. Ground
3. RTS
4. CTS
5. TXD
6. RXD
7. ? - maybe power in?

Connecting Ground to an Arduino ground, and TXD to a digital in gave a nice serial stream of data from the GPS

A bit for experimenting and research found that the serial data is also available via the USB port. Simply chopping off the end of a $2 mini USB cable and connecting the ground (black) wire to the Arduino ground and (green) wire to a digital in pin gave me exactly what I needed.

Also connecting the +5v wire (red) to 5v on the Arduino will power/charge the GPS. I didn't check the drain on this pin but I would be careful connecting this up with a flat battery as the charger may draw more current than the Arduino is able to safely supply.

So here's some code to get it working:

#include 
#include 

/* GPS */
#include "NewSoftSerial.h"
#include "TinyGPS.h"
NewSoftSerial gpsNSS(9, 0);
TinyGPS gps;

void setup()
{
    /* Serial output */
    Serial.begin(38400);
    Serial.println("Waiting for GPS");

    /* Start GPS */
    gpsNSS.begin(38400);    
}

void loop()
{  
    while (gpsNSS.available()) {
        if (gps.encode(gpsNSS.read())) {
            float lat, lon, alt;
            unsigned long age;
            gps.f_get_position(&lat, &lon, &age);
            alt = gps.f_altitude();
            
            /* Display new GPS data when we get it */
            Serial.print("Lat: ");
            Serial.println(lat, 5);
            Serial.print("Lon: ");
            Serial.println(lon, 5);
            Serial.print("Alt: ");
            Serial.print(alt, 1);
            Serial.println("m");
        }
    } 
}

Connect the GPS to Ground and Pin 9. Uses NewSoftSerial and TinyGPS libraries from Arduiniana

Tags: arduinodiy streetviewstreet viewgpsholuxgpslim236streetviewtrackview