An Eccentric Anomaly: Page 3: Programming

Ed Davies's Blog

Pages tagged: Programming

Programming and related frustrations

Burning Oil

Oil Use

The house I'm renting has oil-fired central heating. It's a leaky old house so burns quite a lot so I've been playing around with methods of reducing the consumption while still keeping things comfy. I got an oil delivery earlier in the week that provides a good point to check some of my measurements.


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I read about one hundred blogs on a regular basis. Luckily, not all of them post every day. Still, most are worth checking for new content fairly regularly which seems like the sort of things computers ought to be able to do.



I don't much like telephones. They're great for “operational” use for updating when you're already expecting visitors, deliveries or whatever. They're also great for chatting (particularly with video), again when you're expecting a call because you've just escalated from chatting on a text medium or whatever.

What I don't like are calls (incoming or outgoing) when you're not expecting things and are put on the spot to make decisions. And they're totally infuriating for transferring data (e.g., giving an address or directions). And the lack of a record is a serious impediment (though I suspect some people see that as a plus, but maybe they have better memory than me).

I don't hate telephones as much as James Fisher does but I can definitely recognise where he's coming from.

So, it's a bit surprising how many telephone numbers I have.


Raspberry Pi Clock

The Raspberry Pi is (in)famous for not having an internal hardware clock to keep time while it's powered off. This can mean that the clock has weird values for a few minutes after the device starts up until it's got a network connection and an updated time via NTP.

There are battery-backed real-time clock boards (“hats”) available for the Pi but I haven't got one. Here's how my logging software deals with this.


Raspberry Pi Setup

I have an “always-on” Raspberry Pi 3 which does logging of temperature, pressure, power use and so on readings from around the house and county.

I've had it just over a year and it's been running the version of Raspbian (the Debian Linux distribution modified for the Pi) that was current when I got it. The logging has been to flat files containing lines of JSON but recently I started switching to a Sqlite3 database but was having problems with the code running on the Pi which didn't happen on my laptop running Ubuntu 17.04. I strongly suspected the problem was the old version of Sqlite3 or Python3 in that Raspbian distribution so decided to upgrade to the latest Rasbian (2017-11-29, based on Debian 9 Stretch rather than the previous one which was based on Debian 8 Jessie).

During the installation on the new system I made notes of what I needed to do to get my code running. For my own future reference and maybe of help to others, here they are.



Some lines which have been in my /etc/hosts file for a while: