Rummys Blog An world of endless Monday

Monday, 8 October, 2018

An IoT Mousetrap Part 2

Filed under: ESP,ESP32,World of Warcraft — Andrew.Rowbottom @ 11:35 am

The Mousetrap code has gone through several iterations, this iteration Number 2  has changed the code quite a lot..

The aim of this iteration was to significantly reduce the “ON” time from 3seconds to reduce the consumed watts in this phase.


I have switched from connecting to WiFi (about 3 seconds on time!) to using espNow sending to a “receiver” permanently connected to my Raspberry Pi, this is to reduce the “On” time during the regular status updated. I’ll try to post some information about using espNow in another post.


The “On” time is now reported as approx 300ms (mainly due to the huge number of status messages I send), well down from the roughly 3 seconds connecting to WiFi and sending using MQTT/HTTPS takes.

Unfortunately this has not made a huge difference to the overall battery life which is still running at around 3 months for a fully charged “600mAh” LiFePo4.

Further investigation is showing 2 major current draws:

  1. the LDO at approx 70µA
  2. the pullup/down current approx 70µA

Iteration #3 will look at how to reduce this .. until I un-solder the LDO Voltage-Regulator I’m limited to removing the pull-up/pull-down current. There are a few options:

  1. switch from using the internal pullup/down to an external resistor
  2. use the wakestub and poll the switch/mousetrap state regularly but not too frequently
  3. use the ULP and poll using that.

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