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JeeLabs: Timestamps and logging
Keeping track of time across different systems is not as straightforward as it might seem: every clock has its own notion of time, and always drifts around to a certain extent. There’s an entire...
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JeeLabs: How to install JET/Hub
Installation… ah, the “joys” of modern computing!1. PrerequisitesTo try out JET, you need:a Raspberry Pi, Odroid, OLinuXino, or similar ARM-based Linux boarda working Linux setup on your particular...
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JeeLabs: Hub configuration guide
The JET/Hub process has two types of configuration settings:startup configuration, such as how to connect to MQTT and the name of the data storerun-time configuration, such as which serial ports to...
View ArticleJeeLabs: Using the built-in database
The “database” built into JET/Hub is set up as a general-purpose key-value store - i.e. persistent data storage which can’t store or retrieve anything other than (arbitrary) data by key. Whereby the...
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JeeLabs: Let's talk about the 'N' in WSNs
The acronym “WSN” stands for Wireless Sensor Network. Ok sure, we all have one or more wireless sensor nodes, JeeNodes or whatever, and they probably work nicely. But how do we manage them? What about...
View ArticleJeeLabs: From crontab to systemd
The crontab “@reboot” approach mentioned in the hub’s installation guide has as benefit that it’s very easy to do, without the risk of messing up anything serious, because it doesn’t involve “sudo”. It...
View ArticleJeeLabs: Creating a long-term mess
So you’ve set up a Wireless Sensor Network, i.e. 2 or more “nodes”, talking to each other via RF. This being a JeeLabs article, let’s say you’re using a JeeNode, JeeLink, or other ATmega/tiny-based...
View ArticleJeeLabs: Centralised node management
There are a number of ways to avoid the long-term mess just described. One is to make the target environments aware of source code. For example by running a Basic / Forth / JavaScript / whatever...
View ArticleJeeLabs: Distributed node functionality
Just to avoid any possible confusion: the case made in the previous article for “centralised node management” is not meant to imply that nodes need to operate in a centralised fashion!This is where...
View ArticleJeeLabs: The JET data store, take 2
This article supersedes this one - but it’s probably still useful to read that original article first.While many of the design choices remain the same, the API has changed a bit. The description below...
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JeeLabs: Day-to-day JET practicalities
Here’s a “JET” engine, for your amusement:This week, I’m going to go into the practical aspects of the JET project: for production, i.e. the always-running hub + MQTT server, and for development, i.e....
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JeeLabs: System requirements for JET
One of the main design goals for JET, is that it must run well on very low-power Linux boards.The reasoning is that you really don’t need much computing power at all to manage all the data flows...
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JeeLabs: JET development mode setup
Since JET is intended to remain always-on, at least as far as the hub is concerned, we need to be a little careful how we introduce changes. The way to do this in JET, is to treat the whole system as...
View ArticleJeeLabs: A new web front-end design
JET is going to need a web interface. In fact, it’s likely that a major part of the total development effort will end up being poured into this “front-end” aspect of the system.After many, many...
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JeeLabs: The PDP-8, half a century ago
In 1965, computing history was made when DEC introduced a new computer, called the PDP-8. It was the start of a long series of incrementally improved models, later to be followed by the even more...
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JeeLabs: Inside the PDP-8 hardware
In 1965, computing history was made when DEC introduced a new computer, called the PDP-8. It was the start of a long series of incrementally improved models, later to be followed by the even more...
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JeeLabs: Computer peripherals in 1965
Ok, so now we have our computer. How does it interface to the real world? How do we talk to it? How do we tell it what to do? Do we login to it? Or is it all about switches and blinkenlights?No...
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JeeLabs: Hey PDP-8, meet Raspberry Pi!
If you would like to experience for yourself how a computer such as a PDP-8 looks and feels, there are several possible avenues to choose from:get in touch with a museum, friend, or hobbyist who has...
View ArticleJeeLabs: Some amazing software feats
The introduction of the PDP-8 series was a disruptive, game-changing event, in that it made computers available to a large group of scientists, engineers, and tinkerers. For the first time, more or...
View ArticleJeeLabs: Forget what you know, please
In the beginning, there were computers. Programmed with wires, then with binary data (the “stored-program” computer), then with assembly language, and from there on, a relentless stream of new...
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