updating our network design

The anemometry will be ready to start, once I’ve sourced the parts – but that reminds me that Iain suggested another building exercise that we should do.  That involves modernizing our network design with the budget Pi Zero.

Our original network design involved the original Raspberry Pi as a base station, receiving temperature readings (and whatever else our sensor boxes are configured to send) from a set of Jeenodes (Arduinos with built-in radios).  At the time, we thought that was the lowest cost, easiest build configuration the market would permit for getting sensor readings from multiple locations in the same building to the internet.

Even though that was only around four years ago, equipment has moved on.  Now we can get a low cost Pi Zero Wireless for less than the cost of the Jeenodes – making every sensor box its own base station.  That brings the cost of a building network down from something like £25 per sensor box plus £35 for the base station, to £14 per sensor box.

Of course, in practice, we know our target buildings don’t have great wifi coverage – but that’s OK.  We can mix and match with our existing equipment to use local radio links where we have to, and wireless where we don’t.  Since the radios themselves have a problem with walls, having both options would give us better flexibility.  We probably have more wireless dongles than we need just now, but we could deploy them by buying a few Pi Zeros without wireless and copying Tim’s approach to cannibalising the bits to roll our own.

This one’s not a very difficult or creative project, but it would help with anyone wanting to replicate what we do, and it gives us a chance to review one of the less good aspects of our existing design – the plastic sensor box.   We liked the tight fit in case anyone decided to shake it, but the lids have turned out to be problematic.  If they press down on the sensor board at all, it tends to stop it taking readings.  That makes it very fiddly to close the box lids and test they’re still working, especially around these bulky DHT22 relative humidity sensors.  I think reviewing the box design will be the hardest bit.


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