Saturday, 21 November 2015

RaspberryPi, Device Tree & why my DS18B20 app is broken

One of the problems with writing about Linux, the Raspberry Pi and technology in general is that posts can quickly become out of date.

I noticed several weeks ago that my server was no longer producing nice graphs showing me the temperatures both inside and outside my house.

I've only just found some time to investigate.

My server problems relate to two posts: this one about how to use the DS18B20 temperature sensors and this one about the OpenWeatherMap api.

Device Tree

Apparently, early in 2015, support for Device Tree was added to Raspbian. A few weeks ago I updated my Raspberry Pi server and lost my thermometers. If you want to know why, you may like to read this long thread:-

I found I could fix my system by running in terminal:-

sudo raspi-config

...and then selecting:-

Advanced Options > Device Tree

...and just turning it off. This is probably the wrong way of doing it and I may live to regret it. But for now, its a solution.


I was using the OpenWeatherMap api to get the current outside temperature. This wasn't ideal as my actual location is generally a few degrees colder that the closest location available on OpenWeatherMap.

The reason this has stopped working is that (as of October) you now need to get an access key. To do this you need to register, create an account & give them all sorts of personal information.

To be honest, I can't be bothered! I'll measure the temperature myself if it becomes an issue.

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