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BFree – A battery-free prototyping platform with CircuitPython for Adafruit

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Re: BFree – A battery-free prototyping platform with CircuitPython for Adafruit

#11

Earlier quoted context omitted.

The ULP coprocessor still uses a small amount of power, as does its few KB of NVRAM. The idea of the intermittently powered FRAM thing is that it can be powered down completely, then start up again and continue from a checkpoint. I haven't read the paywalled article, but it looks to me like the main contribution in the project was hacking circuit python to transparently checkpoint itself every so often, so that it ca…

Yep. I think for limited resources, micro-py is the wrong approach. That it is interpreted aside; I had a lua-based interpreter crash because the stack/heap in a nested routine (ie lots of nested fn calls) managed to fill up available memory.

Sounds almost like an ideal use case for Oberon to me - perhaps with remoting the UI or something like that. Chances are that a full environment would still be smaller than this micro-py thingy, whatever that is.

Re: BFree – A battery-free prototyping platform with CircuitPython for Adafruit

#12
post #10

This does look like a great project for in-the-field devices. Especially in literal fields where power is hard to come by. But I see no mention of atomic operations, which would be critical in such a device. Even the trivial action of associating a timestamp with a sensor measurement would require an atomic method. Sure, one could take the timestamp before and after a method runs and reject it if the stamps surpass s…

> Especially in literal fields where power is hard to come by. Is it really? A square centimeter of a photovoltaic surface should provide you with at least a milliwatt of power on average. Thas's not to be scoffed at IMO.

The device might see that milliwatt for two minutes twice a week during winter in some locations. Planning in the field devices means planning for the worst case scenarios, not the common scenarios.

Re: BFree – A battery-free prototyping platform with CircuitPython for Adafruit

#13
post #10

Earlier quoted context omitted.

> Especially in literal fields where power is hard to come by. Is it really? A square centimeter of a photovoltaic surface should provide you with at least a milliwatt of power on average. Thas's not to be scoffed at IMO.

The device might see that milliwatt for two minutes twice a week during winter in some locations. Planning in the field devices means planning for the worst case scenarios, not the common scenarios.

A square centimeter is a very small surface, though. Scaling it up for the worst case is hardly a problem. The board in the picture has dozens of square centimeters on its own, so wherever that board can be used, clearly a much larger PV area can be used as well.
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