Build log 1- prototyping

A project log for DIY Data Logger

An easy to build wireless data logger that I'm using to analyze mountain bike suspension performance

jeromekeltyjeromekelty 08/12/2014 at 18:520 Comments

The first thing I did was play around with the Spark Core and OpenLog with a bit of code and a few random sensors to see what kind of data rates I could get. I quickly stuck everything on a breadboard and wrote a bit of code to log some data. The Tx line from the Spark Core was connected to a FTDI adapter so I could view the data in a serial monitor as it was being written to the OpenLog SD card. Worked like a charm! I was logging data at 200Hz (one reading per sensor every 5 milliseconds.) To put that in perspective, the RaceTech ShockClock data logger logs 2 readings approximately every 4 milliseconds. Given that it takes roughly 25ms @30mph for a 26" wheel to absorb the upward impact of a 4" tall square edged bump I think 200Hz will be fine.

 For the sake of comparison I also tried logging with an Arduino Uno and I was able to get data logged on average around 500Hz (it would start out around 1KHz and then drop to around 700Hz before settling down to an average of 500Hz.) I also tried an Arduino Pro Mini 3.3V I had on hand and it wasn't any faster than the Spark Core. Interestingly the Pro Mini would slow down dramatically as I logged more channels.

I removed the SD card and renamed the .TXT file as a .CSV file and plotted the data on a graph using -piece of cake!