In The Air – Week 18

I needed to work on a few things before tomorrow’s final summary post and challenge deadline. Here’s a quick overview.


The little boosterpack I soldered last week works! I am able to make more stable measurements using the CC3200’s ADC. The Energia sketch was updated to make the conversion back to the actual voltage and then convert it to dust concentration (mg/m3) based on the graph provided in the dust sensor’s datasheet.

Screen Shot 2015-02-26 at 20.54.55 Screen+Shot+2014-12-11+at+22.14.26


I’ve also been working on the OpenHAB config to get all monitored parameters nicely categorized and organized. A debug menu has also been foreseen, providing additional values for troubleshooting purposes.

Here are some code snippets to better understand how I’ve created my openHAB configs.

The items file contains the monitored parameters of a remote sensor using MQTT. In the item definition below, you’ll see how every item takes the value from a specific MQTT topic. The item file can easily be expanded with new items for extra parameters or extra remote sensors.

The sitemap structures all the data in the web interface. I opted for a view per room, with every room containing all the monitored parameters. Just like the items file, the sitemap can easily be expanded to contain more rooms.

The rules files contains some logic to trigger actions depending certain values. For example, when the socket’s state is set to ON or OFF a specific value is sent to the MSP430FR5969 Launchpad in order to control the fan with filter. Turning the socket ON or OFF is based on the measured dust concentration.

The events log shows that the fan is triggered to filter when the dust density reached a value higher than 0.1mg/m3.

The other way around works as well. When the dust density has reached a normal level again, the filtering system is stopped.

Screen Shot 2015-02-22 at 13.53.16 Screen Shot 2015-02-22 at 13.52.57


Finally, I’ve been making progress on the enclosures for both the control unit and the remote sensor. I milled additional “layers” for the control unit, which when combined, result in an enclosure capable of holding all the electronics involved.

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For the remote sensor, I’ve been running into some issues with my printer. Because the enclosure is too big for my current print platform, I split the part in two. Printing the first part went well and the result was as expected. Things started to go wrong when printing the second part. For some reason, the printer’s X-axis is skipping frequently. Why this didn’t happen with the first print is a mystery. I’ve been troubleshooting the issue, but with time running out, alternatives might need to be found. On the bright side, I now know my printer is capable of handling huge bridges without support material, which is rather nice

photo 1 photo 2

The final enclosures will be revealed in tomorrow’s final summary post (because I’m still working on them).


We’re about to enter the last day of the challenge! The solution works, but there are still a few details I’d like to take care of before the final submission. See you tomorrow!

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