First Proof of Concept

I've managed build a first, quite lo-tech, prototype to make sure that my idea of using 1-wire networks is sturdy enough. My initial look at ibuttons proved them to be too fiddly for the kind of use we need, and so my thoughts turned to something more robust: 1/4" Jack(TRS) Plugs, as used in telephone exchanges in the days of old.

I connected up a number of sockets in a small circuit that had one Silicon Serial Number chip attached to it, and then hooked that back to the 1-wire reader using a guitar lead, and could read one or more chips on the network without a problem. I built a second box and could daisy chain them together, using 10 meter cables. This makes me confident that this will work in a real environment.

The low cost of TRS plugs and the Silicon Serial Number chips, and the simplicity of the network, really appeals to me in making this practical. Earlier networks I'd imagined with lots of intelligent collectors for each network, feeding back to a computer; which would have been expensive and more prone to errors, this one is much more simple.

The only real issue is one of context. I'm unable to detect which chip is plugged into which box when they are chained together, and so this is pushing me towards having multiple 1-wire readers: Though I'm not sure how well the host computer will handle that.

It's looking much more likely that we'll use a micro controller somewhere as well, so it may be possible to read the multiple networks from that. The use of a micro controller comes from the desire to have our computer hidden away, so the focus is on the mapping, not a computer screen.

We've realised we want to capture other input, such as photographs or video, and an easy way of doing this. I've suggested a 'start/stop' mechanism, where a button get's pressed to start the mapping, then pressed again to stop the mapping. This will allow us to grab a time stamp, then when we copy images from a camera we'll be able to tell which mapping they belong to by the time they were taken, to make reconciling maps to collected data easier.

the start stop will also allow us to work out how long it takes to do a mapping, and capture other data such a GPS, or weather, or anything we decide on.

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