View Full Version : HVAC thermostat SmartStat Micro (using Teensy) at JavaOne 2013 Sep

07-29-2013, 08:50 PM
They must be hard up for presentations, since ours was accepted: a small, inexpensive, open-source firmware programmable thermostat using in part a Teensy module: SmartStat Micro (https://oracleus.activeevents.com/2013/connect/search.ww?eventRef=javaone#loadSearch-event=null&searchPhrase=Smartstat&searchType=session&tc=0&sortBy=&p=&i(11180)=20801).

It uses the TMP102 and HIH613X sensors (either/or, the HIH613X gives humidity and temp), a small 16x2 OLED display using the WS0010 chip which also has a 100x16 graphic mode, and the Wiznet 812MJ module. At the moment we are using Teensy++2 since that all stacks together nicely with the PJRC adapter board, but are planning to move to Teensy3. The TMP102 are about $2 singles and once configured can act as a self-contained thermostat with a call for heat (or cooling) output and programmable hysterisis (also called deadband, but that doesn't sound as nice).

One of the first in-place tests will be driving the 1 HP 240 VAC evaporative cooler here at the office. In this case I need to switch two legs of 120V at 10A which together comprises the 240 single-phase. It's an old beast: newer models have the same cooling capacity at 120V and less current.

We might offer a kit or partial kit of parts (the SSRs are rather pricey but there are many surplus modules available at reasonable price).

We will also be logging data to a cloud service and/or Google App Engine which could aggregate data from numerous SmartStats. I'm interested in doing this to get a log of outside temp/humidity and inside temp/humidity to monitor cooling efficiency as well as cooling load.

After JavaOne I plan to continue down this path and make this part of home and office radiant heat control and monitoring.

As soon as we have a public project site up I will update here. It's planned for all the software and firmware to be open-source as well as schematics and general project documentation (BOM, theory, etc).

Best regards
Bruce Boyes