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A project log for WiFi AC controller

WiFi-enabled controller for AC units which accept an analogue control signal.

Maya Posch 6 days ago0 Comments

Earlier today we had this:

Which now looks like this:

That's the first WiFi AC controller node (of 5 total) installed in an open plan office room. Initial tests show that the installed sensors (CO2, temperature, etc.) are functioning as expected, with the three connected AC units being supplied with an analogue signal.

Outstanding issues at this point with the controller itself are some remaining (software) issues with the PWM routine (causing too much noise and a 1.5VDC lowest output on the controller), and a regression with the TLS handshake, causing an out of memory situation.

As a result of this the connected AC units are supplied with at least 1.5VDC at the moment, causing their fan to keep spinning, albeit at a slow speed. It's expected that fixes to the firmware to get the PWM frequency at the target 1 KHz will fix this. Ideally an OTA update to the installed unit will suffice to fix this.

Similarly for the TLS issue. This issue has been reported to the Sming project and I'm looking into it myself as well. Maybe it's going to be as simple to solve as the i2c bus issue which I was dealing with a few days ago, which turned out to be just swapped pin parameters in the i2c initialisation function.

Another big remaining TODO is the lack of any kind of backend to control and drive the WiFi AC nodes with. This will be rectified over the coming days, so that one no longer has to manually send binary messages via MQTT to the target node :)

Once this has been completed, and things are more or less working, I'll start working on open sourcing the board design (the v1.1 redesign) and the accompanying software. Stay tuned.


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