hacking a smoke detector

http://www.ti.com/lit/ds/symlink/tpl5111.pdf 35nA thing that controls pwr converter and shutdown via gpio. only works with up to 5v though, not nine volt battery. so minimal power conversion still would be necessary.

01:49 am - no boards ordered.

When breadboarding around I've noticed that I made a fatal mistake in that I've connected every GND signal, where there should have been two GNDs that will only be connected when the MOSFET is turned on by the 4001 NOR gate RS Flipflop. So at this point the boards can only be used as breakout boards.

I still have to test the transistor circuit, I think I have it the other way around. I'll test that tomorrow to be fully sure this time. I think I have to pull it low with a resistor and use a PNP instead to reset the flip flop.

I thought about using "dual 2 input nor gates" for the flip-flop circuit, because of space and maybe I could add a battery monitoring circuit to it then. But those aren't as cheap as 4001 chips.

D'oh!

I think I messed up two things:

1. the signals are not right - the NOR gate outputs should be the other way around
2. I have no transistor on the ESP to change the state of the flip flop

I guess I have to wait on the parts and test... meh. Wasted day

Amazon Dash button seems to work in the same way (button activates power supply, device shuts down afterwards)

This video (and also projects from @Radomir Dopieralski) inspired me to use the Wemos form factor

I thought a bit about the design and decided to make it compatible to the Wemos D1 board, but also put a minimal "FTDI + ESP12" configuration on there, so the maker can decide what he will build.

Since GPIO15 is pulled low anyway and I'm able to use it - why not make it the latch off pin.