Temperature and humidity

Recently the down pipes in my block of flats got blocked. The roof is flat, and a foot of water collected on it before it started to come in. Not just a bit: the flat upstairs flooded, with 2 inches of water on the floor. Our flat was the least worst affected.

Anyway, I now want to monitory the humidity in each room in the house.

A colleague of mine had written this, basically to settle an office dispute about air conditioning :). It's been through various iterations but it's using an ESP8266. Since someone else has done the hard work, I figure I'll use it. I've simplified it for home use, which is to say I just send data to Graphite over UDP, rather than MQTT. Even this modest change caused some pain: you have to copy the host name into memory before you can pass it to the UDP library? Anyway, I figured that out by reading the MQTT library.

I also used a different sensor - an AM2321 which seems to be regarded as generally superior to the DHT22. I didn't have any trouble getting that to work.

After just connecting it with some jumper jerky, I tried soldering something together. I seem to have dramatically reduced the accuracy of the device doing so, so the next version had better use some sort of connector.

I've used double sided perf-board because this one just happens to be the right size. I've got quite a few of those, bought cheaply from hong-kong.

This did also have a switching power supply and a battery connector. I removed that when I found it chewed through a 9V battery in 1 hour flat, and also got warm. It was right next to the sensor, so that was no good!

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