On Mon, 16 Oct 2017 21:31:06 -0400, rickman wrote:

> Allan Herriman wrote on 10/15/2017 3:42 AM:
>> Assuming you can figure out how to derive such a signal (e.g. by
>> monitoring cell voltage, or by starting a timer when the charging input
>> fails), I guess you could try to couple it to something like this:
>> https://shop.pimoroni.com/collections/raspberry-pi/products/onoff-shim
>>
>> "It watches the state of BCM pin 17 and, when pulled low (pressed), it
>> initiates a clean shutdown. Last thing, just before your Pi shuts down,
>> BCM pin 4 is pulled low to completely cut power to your Pi."
>
> If the Pi pulls BCM pin 4 low to cut power (I assume on the power
> source) how does the circuit get powered back up?  Once power is cut,
> pin 4 won't be pulled low anymore.  I guess it has to be a momentary
> input controlling a state on the power controller.  Then something else
> has to change the state and turn power back on?

As part of installing it, you solder a momentary contact switch to the
board. Pressing it powers the RPi up if its off and shuts it down if its
on. There is control software associated with the board. It will power up
without it, but the software must be installed on the RPi for shutdown to
work.

Or so it says on the referenced Pimoroni page.


--
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |

--- SoupGate-Win32 v1.05