It was a bit of a fight to get the SparkFun microSD Shield working. At first, I thought it was my choice of cards. Then, on reading the manual (ahem), I discovered the section “I downloaded a FAT library for Arduino on my own from the Web but it’s not working! Why not?“. It seems that the SparkFun shield uses non-standard pins for signalling, which they consider a feature, but some consider a bug.
After fixing the code in the awesome sdfatlib library, I’ve now got it logging the temperature of a cooling container of hot water:
You might just be able to make out the LM35 pressed up against the measuring cup.
I remember making a right mess of this experiment in my school final Physics practical exam. I also used to do this in my first job when bored testing Campbell CR10 dataloggers, making a nice 1-d cooling curve with a thermocouple and a cup of hot water.
I think the heating came on a couple of times, as there shouldn’t be bumps in the curve. Here’s the data.