jdl2001 wrote:Ken,
Very cool. I'm in the process of integrating a compass into the GPS logging and may eventually work in an accelerometer. I have a separate accelerometer that I have been playing with and one of the things that surprised me was the sampling rate required to capture what I felt was reasonably mild motion. Just moving the accelerometer by hand relatively gently, I found a significant difference between 16 and 128Hz sampling.
Long-winded way to get to my question. For the GPS I am using, your approach would be limited to sampling the accelerometer at 1Hz; I don't think this would be of much use other than as a tilt sensor. Have you thought about sampling the accelerometer at a faster rate between GPS samples? Could you share what your intended application is?
Thanks, I am 2 weeks into the Arduino experience...fun stuff!
I am going to use the logger to keep track the position, speed, and acceleration of my car while on a racetrack. I opted for the 5Hz GPS so I could have better resolution of the position, but I haven't really thought about the sampling rate for the accelerometer. To be honest, I'm struggling enough just trying to get everything to work. I have had a lot of help from a good friend of mine, or I never would have made it this far.
My guess is you could log at a faster rate. The only issue is that it would report the same GPS information until the GPS module updates.
How is your project coming? I'm actually beginning to do some research to do a VERY similar project. I think the only different is that I'm going to be putting it on a motorcycle and not a go-kart. (:
Any tips to keep in mind before I start purchasing parts?
My buddy mounted the unit in a box and then put switches on the box for the reset button and the jumper. This makes it a lot easier to start and stop recording. However, we had problems with the sketch becoming corrupt this weekend when we tried to use it. As I was also breaking in my car, this took a backseat and I haven't had time to look into it.
The big tip for buying parts is to make sure you buy the female socket for the GPS module if you use anything other than the default. I bought the 5 Hz module and didn't realize I would need the socket. The PCB has a spot for it, but you need to buy the socket and install it.
Also, get the extended posts so when you stack the shield on the Arduino you can actually reach in and remove the SD card. Another trick is to put a piece of tape on the SD card to give you something to grab. I will try to get some pics up.
I used the ETek EB-85A module. It does require some changes to the code. First, you have to change the baud rate to 38400. Also, the strings to turn functions on and off have to be changed. My buddy and I figured out the new strings by reading the manual for the chip and then coming up with a checksum equation.
Hey BB, I've been plugging along trying to do something similar to you for a while now [I'm not good at staying focused on one thing I guess]. I'm having a strange problem that seems related to the ETek chip. You have any advice?