Securing MySensors network

Some months ago I decided it was time to secure my steadily growing MySensors network. As described on the MySensors website this can be implemented by using a software or hardware solution to sign messages. I chose the hardware solution using the ATSHA204A component. Because the more convenient break-out board was out of stock, I ordered a little strip of 3-legged ATSHA204A surface mounted devices (SMD). But when they arrived I was struck by the size of those things.

Feeling steady handed today I took the nerve to solder one of them to put on my gateway device. This gateway device consists of a Arduino Uno, Ethernet shield (W5100) and nRF24L01+ PA/LNA. There are some nodes (Sensebender Micro) in the house which are already equipped with an ATSHA204A.

Somewhat proud of my accomplishment I like to share some picture of what it looks like.

Curious and want to know more about securing MySensors, check out the following page.

Home heating setup using openHAB

openhab-logoThree weeks ago I finished my home build thermostat and heater control using openHAB and MySensors and I am really pleased with the result so far. The set-up consists of two Arduino Pro Mini’s, one 3.3v for the battery powered MySensors temperature sensor in the living and one 5v version for the relay control placed next to the heating unit. Because I didn’t like the idea of controlling the heater over a wireless connection I used an Ethernet module for connectivity. I also added two temperature sensors for measuring the heat in and out of the heater. I eventually ended up by using only the temperature reading of the one that measures the returning heat flow in order to minimize the overshoot. I’m still fine tuning the heating rule, so I will publish the code when I’m completely satisfied.

Have a look at the screen shots below to get an impression how it looks like in openHAB.

Screenshot from 2015-01-22 22:41:39 Screenshot from 2015-01-22 22:42:05 Screenshot from 2015-01-22 22:42:51

More on this subject to follow..

Low power mod for Arduino Pro Mini

sparkfun_logoToday I replaced the Deek Robot Pro Mini clone by an original Sprakfun one. Although the clone worked quite well I could not manage to cut the traces right to preserve power for this battery powered Arduino. In an attempt to disable the onboard power regulator and LED I wasted two. The nice thing about the latest version of the Sparkfun Arduino Pro Mini 328 (3.3V/8MHz) is that it comes with a desolder mod that will disable the on board LED and power regulator. Have a look at the uploaded image.


When the on board power regulator is disabled you have to power it with regulated 3.3v, so disable the VCC pin on the FTDI header.

As soon as it runs steady for a couple of days I will try to add the following battery measurement adjustment described on the MySensors battery powered sensors page. And I will give my Multimeter a try on the current power usage. So more on this topic later.