Fully powered by the USB port
A DIY in-car navigation system
Two versions available - External Antenna (pictured left) & Internal Antenna (pictured right).
Two versions available - External Antenna (pictured left) & Internal Antenna (pictured right).
| Description |
This is one very compact USB receiver that can be built in hours and for a small cost. What more it requires no batteries as is powered from the USB port on you PC or Laptop. This is the perfect companion for that trip to the country or a quick trip around the suburbs as your position can be plotted onto a map or street directory in real time. Just the thing for that laptop based in-car navigation system!
The heart of the unit is based on Trimble's Lassen SQ embedded GPS module. This postage stamp-sized GPS module is one of the lowest power units on the market and measures just 26x26x6mm in size. It supports both the standard NMEA 0183 format and the Trimble Standard Interface Protocol (TSIP). NMEA messages that are supported are GGA, VTG, GLL, ZDA, GSA, GSV and RMC. This module is designed to be used in a host of applications mainly portable handheld, battery-powered applications.
This is one very simple GPS to get running. Just connect the antenna and then the USB cable to your computer and it starts running. Drivers are required for this USB device and maps a virtual COM port to this GPS unit. With the virtual COM port drivers this module is made compatible with all the good mapping software and terminal programs. This great USB unit can be programmed to output NMEA 0183 or TSIP using Trimble's SQ_monitor shown below. Changes can be saved to internal Flash, so this unit automatically powers up in the right mode for your application.
An internal lithium coin battery (if fitted) saves the Almanac, last position and time so the unit can power up in just 45 seconds (Warm start). Without the battery this GPS unit can take around 3 minutes to get the first fix.
| So what's inside the unit? |
Apart from the Lassen SQ GPS module, the other main component is the FTDI USB to serial chip. These great little devices transfer serial data down a USB cable into your PC. Good Bye to the serial port! What more FTDI supply Virtual COM Port (VCP) drivers that make the serial data look just like the old serial ports on you PC. This FT232BM chip converts all the GPS data to USB for this project.
To meet USB specifications a MOSFET is used to turn off the GPS when the computer puts this GPs into suspend mode. The only other useful parts are a lithium backup battery to keep almanac and time data in the GPS module and a EEPROM for the USB chip. This EEPROM is used to hold a serial number and device name.
The Lassen SQ draws just 40mA @3.3V so you don't have to worry about this extra load on the laptop battery!!
| The Software |
Trimble can supply this great little program call 'SQ Monitor' for testing and setting up this GPS module. Just run the program and set the COM port and the GPS data should appear on the screen. All the usual data is displayed (position, time etc) and extra information on satellites used for the position fix. These satellites are displayed in green.
This software can be used for setting you PC clock and even logging the GPS data. What more could you ask for?.... Well that is were the next software program comes in!
If you want to have in-car, in-boat or even in-plane navigation, all you need is this software and a laptop to run it on. OziExplorer is a realtime moving map navigation system written in Queensland, Australia. Once setup this software plots your position, from the GPS, on any compatible map in real-time. Oziexplorer requires data from the GPS in NMEA 0183 format.
Be sure to check out all the details at www.oziexplorer.com
| Where from here? |
This GPS unit is perfect for many commercial applications like car/boat/buoy tracking, data logging of temperature, humidity and position for transportation of perishable goods (fresh food). The uses are endless.......... There are many hobby applications too.
Picture right was the first prototype of my Vehicle tracking system. Inside is a complete data logging system with GSM modem. The Lassen SQ was used for the GPS position fix, while a GR47 GSM modem allowed me to SMS the vehicle for its position. The System would log data once the car was detected to travelling faster than 5Km/h. The data logged was position, altitude, time, date, speed, temperature and humidity. A SHT11 digital temperature and humidity sensor was used.
| Sales |
Download the file, USBGPS.pdf
Download the file, GPSAdaptor.pdf
PCB, with 8 pin SMD connector and header - NO LONGER FOR SALE
PCB with Lassen SQ mounted, external Antenna - NO LONGER FOR SALE| Software, Datasheets & links |
These Trimble Lassen SQ GPS Module's come from STEP Global.