Has anyone hacked a Logomatic to log 0V-5V analog signals, rather than 0V-3.3V?
I just ordered a Logomatic serial data logger, which I’m hoping to use to log a 5V analog signal from a gyroscope. I’m trying to max out the precision, so I was wondering:
Is there a convenient place I could tap onto the reference voltage pin for the Logomatic MCU’s AtoD converter? I could then connect it (through a 2/3 voltage divider) to my gyro’s reference voltage.
I have some very accurate 2/3 voltage divider chips coming, but I would be happy not to use them at all. If anyone has other good ideas, please let me know. Thanks!
-Adam
Hi,
no response on this topic? Have the same situation.
Andreas
I e-mailed SparkFun tech support and I did actually hear back from them. For a bunch of reasons you can’t run the Logomatic at 5V.
I ended up settling for running the reference and the signal voltages through voltage divider circuits and logging them both. It’s not really as precise, but it turns out the reference voltage was pretty stable anyway, so we’re not even using that information.
What really helped was using surface mount resistor arrays as our voltage dividers (like [this one). They’re resistor pairs (in this case 1Kohm and 2Kohm) manufactured in one small package, so they temperature-drift together and their ratio (and thus the voltage division factor) stays close to constant.
If you really wanted to you could desolder the reference voltage pin of the ARM chip, lift it up off it’s pad, and connect it to a divided reference voltage (3.3V or less!) to get better ratiometric data logging, but if you need data logging that precise you might want to look at other data acquisition systems, [Dataq has some cheap USB AtoD boards.
-Adam](http://www.dataq.com/)](Electronic Components and Parts Search | DigiKey Electronics)
Thank you very much for you quick answer, Adam!
Andreas