Computing stuff tied to the physical world

Micro Power Snitch, part 3

In Book on Mar 4, 2015 at 00:01

There’s trouble ahead for the MPS: it’s not reliable enough yet, and can enter a “zombie mode” whereby the µC won’t have enough voltage to start up, while drawing so much current (relatively speaking) that the energy source isn’t able to raise the voltage further.

Leading to some beautiful pictures, but nevertheless totally undesired behaviour:

SCR05

The daily articles in this week’s episode are:

So far, it looks like this second MPS design solves the problems of the first. Progress!

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Micro Power Snitch, part 2

In Book on Feb 25, 2015 at 00:01

So far, there’s an idea, a circuit to collect energy, and sample code to make an LPC810 come alive every so often, briefly. It’s time to tie things together and see what happens!

As usual, one article per day in this week’s episode:

As you will see in Saturday’s article, this first MPS design is indeed able to power an LPC810 µC after some modifications, and keep it alive “under certain conditions”.

DSC 4953

But there’s a very nasty skeleton in the closet – stay tuned!

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Micro Power Snitch

In Book on Feb 18, 2015 at 00:01

It’s time to tackle a fairly ambitious challenge: let’s try to make an LPC810 run off “harvested” energy and use it to periodically send out a wireless packet.

This week will be a short intro into the matter, with more to follow later:

To lift the veil a bit, here’s the energy I’m going to try to harvest:

Ct shape

This is the voltage from a Current Transformer (CT), when unloaded. Such a CT needs to be “clamped” around one of the wires in an AC mains cable, and will then generate a voltage which is proportional to the amount of current flowing in that wire.

Well, maybe, sort of…

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