On GPS Accuracy with the Tripmate

I am a huge fan of my Delorme Tripmate. It’s a cheap serial GPS receiver that it is very easy to work with and interface with my microcontroller projects. It was introduced over 10 years ago and mine is still in great condition. I’ve used it for a number of projects (e.g., PIC16F88 Delorme Tripmate GPS Logger, GPS Logger with Time and Speed, and a modified version for GPRMC) and I plan on creating more. However, it’s starting to show its age and I have found that over time I’ve become less and less fond of its chipset. The biggest problem has been the gross inaccuracies in reported position. (more…)

Tracking a Bike Ride & PIC16F88 GPS Logger DR1r7

My original intention for my PIC16F88 Delorme Tripmate GPS Logger and GPS Logger with Time and Speed was to log my runs around Lafayette and West Lafayette. However, I’ve found that the weight of the GPS makes it a real pain to lug it around. Running around with a weight bouncing around in my backpack is no fun. Now that it has gotten warmer and the sun is shining ’til 9 PM (really more like 9:30 PM), I’ve been biking quite a bit. The lower impact nature of bike riding makes it much easier to carry the Tripmate GPS receiver. So I took went out this afternoon for a ride to see how it performs:

2007-06-15 Bike Ride Path Thumbnail

And the ride did not turn out too bad! (Click the image above to see a better view of the route, outlined in yellow.) There are some problems with the logging, but this can be attributed to the quality of the fix (most likely 2-D for most of the ride) and the tendency for the GPS to loose its fix when the sky was occluded. See the upper right of the path where I went biking through the woods and you can see that it lost the fix from the time I entered the woods to the time I left them. Continue to the post for more information and the updated firmware. (more…)

PIC16F88 Delorme Tripmate GPS Logger with Time and Speed

I’ve updated my PIC16F88 Delorme Tripmate GPS Logger, so it now includes time and speed logging. Using the trip information recorded by the GPS logger, you now have even more variables to play with. For example, using time and velocity information, one can plot not only the speed, but also the acceleration of the car (dv/dt) for a trip:

Continue to the post for more information about the updated firmware, usage instructions, and limitations of this firmware. (more…)

PIC16F88 Delorme Tripmate GPS Logger

This project focused on creating a simple serial data logger for the Delorme Tripmate (also known as the GPSTripmate). The Tripmate is an older GPS receiver that can be purchased on eBay for <$20. I happen to have one that my family used a couple of years ago and it is still in great shape. It has been sitting in the back of my car for the past four years, so I finally decided to put it to good use. The plan was to create a GPS data logger that would record the position of the unit and allow me to read back the latitude and longitude after acquiring the data. My ultimate goal will be to use a small backpack to record my runs (once the weather warms up). This was a fun experiment because not only did I need to interface the PIC16F88 to the Tripmate, but I also needed to parse the output and implement an efficient storage solution. Read on to find out more information about the project, see the schematic and soure code I wrote, and find out how the data was visualized. (more…)