USB Current Meter

…or USB power meter?
…or USB KEY AVR Tiny split core interface?

Call it however you want, this project is a small USB key sized circuit to interface an USB system with a single split core current sensor using an ATtiny85.

These non-invasive sensors are widely available on eBay and similar for a reasonable price (around USD$ 30 for the one I used) and let you measure the current flowing through an alternate voltage line, like house mains. This can be used to get a gross measure of instantaneous power consumption, allowing you to make a graph out of it and plot your power usage profile, or just to check how much power a device is using.

A friend of mine is using this one side-by-side with its photovoltaic inverter to upload his data on, a nice website for photovoltaic plant monitoring.

This also shows a rectifier circuit to acquire data from an alternate voltage source without dual power rails.

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Network Statistics with iptables and rrdtool

Netfilter is a powerful tool when it comes to select traffic on a Linux router.

When you set up a chain of rules with iptables, you are also get set of traffic counters with each rule you set, which can be used to see how many times the rule have matched.

If you place a chain of rules without any jump, the packet get counted and goes forward the chain, so that you can write a set of rules just to get some statistic of selected pattern of traffic in your network.

In this post I’ll show how to write some simple rule, get the data on a rrdtool database and plot a traffic graphic out of it.

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USB Sensors with ATtiny Microcontrollers

Working with embedded electronics, you will eventually ends up with some sensor between your hands, here I’ll show how to make a graph out of it!

This project involves a light sensor, a tiny 8-pin AVR USB key with the V-USB stack, a GNU/Linux system and rrdtool.

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