Author Archives: edmallon

Switching off SD cards for Low Power Data Logging

The tweaks I discuss in the  power optimization post bring sleep current on a typical build into the 0.1-0.12mA range; leaving the sleeping μSD cards  as the largest remaining power consumer on the Cave Pearl loggers.   And those cards have been a burr under my saddle for quite some time now, as they … Continue reading

Posted in DIY Arduino Datalogger, The quest for low power | 9 Comments

Calibrating Thermistors on a 3.3v Arduino

Selecting a thermistor (& series resistor) value Most of the material you find on thermistors makes the assumption that you are trying to maximize sensitivity and interchangeability. But oversampling gives you access to enough resolution that sensitivity is less critical, and interchangeability only makes sense … Continue reading

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Improving Arduino ADC resolution with Dithering & Oversampling

While I was figuring out how to read thermistors, I came across claims that you can improve the resolution of any Analog-to-Digital converter with a technique called oversampling & decimation. I had already doubled the number of ADC bits covering my target temperature range by powering a thermistor divider from the rails … Continue reading

Posted in Developing other sensors | 2 Comments

The 2016 Cave Pearl Project ‘Year in Review’

We made great strides in 2016 with development of new calibration procedures and continued refinement of the housings & connectors for multi-sensor builds. At this point I’ve cobbled together more than 130 loggers for the Cave Pearl Project. While I still have a way to go before I … Continue reading

Posted in Expedition Reports & Updates | Leave a comment

DIY Arduino ProMini Data Logger: 2016 Build Update

Its been almost a year since the last stand-alone logger tutorial, and I continue to receive questions from people adopting the platform in education settings.  That feedback makes it pretty clear that soldering is the biggest stumbling block for beginners, so I have reconfigured the build to use pre-made … Continue reading

Posted in DIY Arduino Datalogger | 12 Comments

Field Report 2016-07-09: I2C pressure sensors work on 20m cables!

With the term prep taking up everyone’s time, I almost forgot to post about the wonderful field season we had this summer.  We really covered the bases on this one: from surface loggers, to cave sensors, to new deployments out on the … Continue reading

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Using the Arduino UNO for Data Acquisition

I recently picked up a ADS1115 breakout board, and it was fairly easy to use that with the serial data plotting capability of the Arduino IDE. It’s not often that something works this well on the first try, and I thought I would post about using  the combination as a kind of … Continue reading

Posted in Developing other sensors, DIY Arduino Datalogger | Leave a comment