The Oak by Digistump > Oak Project Ideas
DriveWay entry monitor array
defragster:
A variation of SensorNet, I want to purchase and modify some solar charging PIR activated motion lights. I have seen (on ebay not tested $15-30) some now shipped with an 18650 LiPo that have a built in solar recharge system. The 18650 is a 3.7v battery with decent reserve power that could enable periodic activation between low power sleep. With good sun recharging they may self sustain.
These units wired with a PIR might be hacked to detect any motion (typically they don't turn on lights when charging i.e. daylight) and if that could wake the OAK/ACORN it could report to the network the detected motion. Even from a cold boot the OAK is seen to be network ready in 6 seconds - perhaps faster from a sleep state or transmit off receive only state if possible.
Problems: Some have metal shells that would inhibit radio signals getting very far up my 500ft driveways. Also they may have limited room inside for adding hardware. And adding an active load on the LiPo may confuse the required control of the detection system that is needed to safely charge LiPo cells. Others use 3 AA NiMh cells that could provide similar reserve. One factor in this is the included solar panel - the $30 unit with 18650 seems to have a larger recharge output which could be important to no maintenance usage. Adding this might take an external wired housing to hold the OAK (and perhaps even a way to switch between a running cell and a charging cell)?
I'll look to buy one or more of the PIR/SOLAR lights and maybe start with a PRO nRF24 solution until the OAK KS hardware is made ready. Any tips on similar experience are welcome.
defragster:
Erik: On KS you once posted the range you were seeing on these? Was it 150ft? It must have been a comment and older posts not paging in for me.
I walked my driveways and 180 feet was the common mounting and clearest line of sight points - except of course an evergreen tree branch may come in at the last - and those hold lots of water some months here. And the two drives are about that far apart - with higher tree count between. Maybe I can find a sweet spot - but no sun there.
OAKs don't do MESH networking - it there an easy way to transmit data point to point up the chain? Manual IP chatter?
Solice:
I was thinking about this when I read your project. I recall Erik saying that the Oaks can operate in access point mode. Perhaps there's a way to leverage this by having an Oak AP (maybe two Oaks, to create an Oak router) to cut the effective total distance between links?
EDIT:
On second thought, that would require you to keep at least one of the Oaks in the Oak router powered up. I'm not sure what the power budget is for this, but it would probably eat right through it like that... Pringles cans?
defragster:
We'll have to see where that goes - on one end I have power at a couple points - but it is the middle where the AP would be needed - with no power and no sun. I'll have to find a decent battery exchange system - or make the units interchangeable and swap them out as needed.
One other thing I saw was - creating a MESH with NRf24 devices to connect? Perhaps those would be lower power with Pro's or something? But unless they gain range and use much less power it would be adding another layer and it seems one OAK would end up like your post and need to have an OAK with both radios active for routing.
dougal:
If you have line-of-sight (more or less), you might consider a cantenna to extend your range directionally.
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