1) The ESP8266 Vdd supply shown is your 3.3V LDO output
for the ESP8266.
2) The ground is the neg side of the battery, the common in
your diagram shown as right vertical leg of your schematic.
3) R2 C1 is a differentiator that takes the step 12 V turn on V from
the tilt sensor, and creates the + going edge into the MOSFET
gate. which turns it on, its drain going to ground, generating RST.
When cap charges from the 12 V step the Vgs of MOSFET returns
to 0 and MOSFET turns off returning the RST pin to 3.3 V.
Remember you have to do the homework to figure out the RC time
constant to meet the min RST pulse width. I cant seem to find a min
RST pulse with, so you may have to experiment with differentiator
values. Guess is 1 - 100 uS. You may set up on bench a switch to
turn on power and look at RST pin on module and see what its
PW is. The Nodemcu module has the following values for RST pin
(nRST) :
In my simulation that produces ~ 10 uS, but the circuits and thresholds
of devices different than Nodemcu. Do the bench testing over some Vdd
variation to make sure your solution is good.
Regards, Dana.