Connecting a Locosys GPS to a Arduino Uno

Using Arduino Project Guidance
1

I understand you cannot have the Locosys GPS AND a USB (laptop) connected to the Uno at the same time. As soon as I hook the GPS to the Arduino power (3.3v and ground pins) my com port instantly drops. WHY? Does it draw so much current that it affects Arduino?? I almost tossed this GPS in the trash thinking it is bad.

2

do you have a datasheet?

3

click downloads tab. Mine is the model LS20031 (TTL). It says 13mA typical current draw. That doesn't seem a lot.

4

I'm new to the Arduino realm... Is it possible that anything plugged into the 3V3 pin for power automatically disconnects the usb/com port for some reason? This is weird.

5

The maximum current available from the 3.3v pin is 50mA, so if peak power consumption is near that it could pull the voltage down. Does it draw more than the nominal rating on occasions, ie when first acquiring signals? (No, I've not downloaded the data sheet)

6

I never could maintain the usb/com connection from the beginning. As soon as I plugged in the usb cable it would power up the Arduino, but no more "com4" in my IDE, weird! As soon as I unplugged a power pin to the GPS it came back up. My GPS is a Locosys, but I read where the same issue happened with a Parallax GPS chip, and I quote "Note: if you are using an Andruino Uno, keep in mind that you can't use the GPS module at the same time as your computer is connected on the USB port." I found this quote here... Arduino Playground - GPS

7

Are you using pins 0 and 1 to talk to the GPS? On the UNO, and similar Arduinos, the Serial port on pins 0 and 1 are in use when you connect the USB port to a computer.
You can have serial I/O to a device, such as a GPS, on those pins or you can have a serial connection through USB to a computer.
If you hunt around you should be able to find some code which uses SoftwareSerial to communicate with a GPS on pins other than 0&1.
As a simple test, disconnect the GPS from pins 0 and 1 and then power it from the 3V3 pin to see if it still crashes.

Pete

8

el_supremo,

I'm not connecting the gps to anything other than power pins. I only hook to 3V3 and ground, then lose my usb/com port. I haven't even got to the serial port yet, bummer.

9

Measure the current drawn by the GPS module using a multimeter.
If you don't have a multimeter, now is the time to buy one!