The Blog

First PCB Prototype

We’ve been testing several wireless prototypes of building sensor nodes and will keep this blog updated on the progress as we go along. In the meantime, we thought it would be cool to make a PCB version of our T/RH data logger. The board was designed in CadSoft Eagle and sent over to OSH Park for fabrication. Here’s is one of the OSBSS data logger prototypes that we soldered (using a hacked $12 toaster oven from Target, obviously):


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Configure DS3234 RTC in OSBSS dataloggers

The DS3234 RTC breakout from SparkFun does not include a backup battery (CR1225). After inserting the battery, the RTC’s oscillator initializes and starts keeping time from 1/1/2000 00:00:00. The RTC’s time needs to be manually setup once. If you’ve already assembled an OSBSS datalogger, upload the following code to configure the current time in the RTC:

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Data from OSBSS CO2 sensor

Months ago the initial prototype OSBSS CO2 sensor was designed and made in BERG lab, so as the next step we tried to verify the sensor’s performance. Therefore, as you can see in the following picture we performed a co-location test with OSBSS CO2 sensor and two off-the-shelf CO2 sensors. SBA-5 CO2 Gas Analyzer and Telaire 7001 CO2 Sensor were used for this reason. In order to record data, the off-the-shelf sensors combined with the Onset HOBO Data loggers. As the first attempt we launched all sensors with one minute intervals and placed them close to each other in the BERG lab for approximately 21 hours.


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Data from OSBSS proximity sensor

Now that our new proximity data logger tutorial is published, I would like to show some data of its performance. Below are photos from a co-location test with the initial prototype OSBSS proximity sensor and an off-the-shelf Onset HOBO occupancy/light logger in our lab. In our first test we simply launched both sensors with default settings and placed them side-by-side on the desk of a graduate student to record occupancy over a period of about 15 hours (we’re watching you, Parham!).

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73 days of data from the 1st datalogger build (revision 09 30 2014)

I previously posted on my first effort building the first complete sensor from OSBSS, a long-term battery powered temperature and relative humidity data logger (revision 09 30 2014), as well as about a week’s worth of data sampling at 1-minute intervals in my office and co-located next to an Onset HOBO U12. Just to test the battery life and clock drift, I’ve left it running since late September until yesterday (December 10, 2014), logging at 1-minute intervals in my office for a period of about 73 days. The sensor and data logger are still functioning normally even at this high resolution of data collection and powered only by AA batteries! The clock appears to have drifted minimally (maybe 5 seconds, although I can’t confirm that). See below!

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Data from custom T/RH data logger – 1st build (revision 09 30 2014)


Two months ago I wrote a blog post documenting my first OSBSS build of our low power (long battery life) air temperature and relative humidity data logger. At that time we were using the SHT15 sensor breakout board to measure both temperature and relative humidity. After some co-location tests with Onset HOBO data loggers and others, we discovered that (a) yes we could achieve low power draw and long battery life on this base framework of a data logger, (b) yes we could achieve accurate relative humidity readings compared to a HOBO, but (c) unfortunately, our temperature readings were not very accurate (they were decent after calibration, but who wants to build a temperature sensor that then has to be calibrated against another, better temperature sensor!?). This last part really bugged us — we simply couldn’t rely on the SHT15 to provide accurate temperature measurements, which then, because RH is based on temperature readings, yielded both inaccurate T and RH readings.

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Custom T/RH data logger version 0.01 – First build


Yesterday marked a momentous occasion for OSBSS: our first complete build of a custom sensor by a non-expert (me!) using our first online tutorial. After about 9 months of work and many stops and starts with various boards, sensors, software, and design concepts, the development team (Akram Ali and Zack Zanzinger) has successfully developed their first low power data logger built on the Arduino platform. It even has its own GUI to launch the logger! The first logger is designed to measure temperature and relative humidity (read the tutorial here). But the really cool thing is that now they have the basic design for a custom data logger with low power draw and a long battery life that can be used to accept any number of other sensors that we are planning to build. We have already prototyped and sourced many of these others sensors, which, combined with the background legwork Akram and Zack have done, should allow for fairly rapid prototyping of new sensors and tutorials. Not bad for a team of architectural engineers without formal electronics training!

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Temperature & Relative Humidity Datalogger using DHT22 and Arduino Uno


The following tutorial will guide you through the process of building your own data logger for reading temperature and humidity and storing it to the SD card at any given interval. We will use one of the most common Arduino boards for this project: the Arduino Uno. This tutorial is aimed for beginners who are new to the Arduino platform.

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Motivation for OSBSS


Recent advances in culture-independent molecular techniques and metagenomic computational tools for analyzing microbial diversity, coupled with the recognition that the majority of people in the developed world spend most of their lives indoors, has led to a rapid increase in the number of studies exploring microbial diversity within the built environment. Recent studies have characterized microbial diversity in offices and other commercial buildings, classrooms, healthcare facilities, homes, and transportation environments, which all represent indoor environments where people spend much of their time. In general, these studies have shown that many bacterial communities in occupied environments appear primarily dominated by human skin, gut, nasal, and/or oral source, with some variability attributed to building ventilation strategies and occupancy characteristics. Conversely, fungal communities appear primarily dominated by local outdoor environments.

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OSBSS is born!


We are very excited to officially launch of the Open Source Building Science Sensors (OSBSS) project! The goal of OSBSS is to develop and document the design and fabrication of a network of inexpensive, standardized, and synchronized measurement devices for recording long-term indoor environmental and building operational parameters that are likely to influence microbial diversity and abundance in indoor environments. Documentation of the development, calibration, and performance of the sensor network will utilize open source hardware so anyone in the world can build their own sensors and sensor networks.