Freezer temp monitor with buzzer, can I set the high temp limit via Vera?

[signal15]

After losing about $1k worth of meat in my freezer today, I've finally decided to get around to monitoring my freezer temps. I'm going to do a regular temp sensor, but add a piezo buzzer and a silencing button.

Originally, my idea was to:

• Monitor the temp
• If it goes above 20F, sound the alarm
• When the silence button is pushed, it mutes the buzzer
• The mute is reset once the temperature dips below 20F again, so it's armed again.

But, then I got to thinking, it would be nice to be able to set the temperature limit from Vera, and have it save to the eeprom so it would survive an arduino reboot. Is this even possible? Has anyone built something like this before?

[gohan]

You can use the savestate function to store variables data in arduino flash, in theory you can send a value from Vera but it only depends on choosing the right supported variable (sorry I'm not expert on Vera).
Why are you bothering about a buzzer when you could have all kinds of notifications from the Vera?

[signal15]

I am doing a buzzer because my sensors so far have been somewhat unreliable with connectivity to the Vera. I suspect it is due to my esp8266 gateway. I am going to build a Raspberry pi gateway though to see if that is more reliable.

[blacey]

@signal15 Sorry for your significant meat loss.

You might want to take a look at the TempLeakSensor device luup files on the Vera for ideas. They declare a security device that can be armed/disarmed and associated temp and water events used to detect a freeze or leak respectively. In your case, you would create a TempSensor device that could be armed and disarmed and define a custom variable for that device that defines the trip temperature. Whenever the luup temp variable for that device is modified using the vera UI, you would send the updated trigger temp to the sensor node.

The advantage of this approach is that you can use your TempSensor to trigger scenes when armed (e.g. freezer door is closed) and the current temp exceeds the trigger temp akin to how motion sensors are used. In addition, it would act as a normal temp sensor reporting the current temperature to your vera that you could plot over time to check your freezer performance/efficiency.