DIY FSR Bed sensor

Otamay · February 26, 2025, 3:37pm

For those users who already have the FSRs and an ESP32 and do not want to purchase an Elevated Bed Sensor:

You can buy one or two NE555 Pulse Module Rectangular Square Wave Signal Generator (I bought one like the following photo but any should work):

Solder your FSR in parallel to the potentiometer that controls the frequency. I use mine in 1kHz-10kHz mode but ymmv. You may even try to power the circuit with 3.3v and it might work, if not you will need a level shifter. Connect the pulse generator output to GPIO pins 10 and 20 and flash your esp32 with the same project from ElevatedSensors:

github.com/ElevatedSensors/sensor-configs

bed-presence-mk1.yaml

ea207e48c

esphome:
  name: bed-presence
  friendly_name: Bed Presence
  min_version: 2024.6.0
  name_add_mac_suffix: true
  project:
    name: ElevatedSensors.BedPresenceMk1
    version: DIY
  platformio_options:
    board_build.flash_mode: dio

esp32:
  board: esp32-c3-devkitm-1
  framework:
    type: esp-idf

# Enable logging
logger:

# Enable Home Assistant API

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You will need to play with calibrate_100 and calibrate_0 yaml values from monitoring esphome logs to proper calibration.

I personally would buy the ElevatedSensors hardware because it is more robust as everyting is integrated in one circuit, but it is somewhat expensive for me considering my location and that I’ve had already most of the parts.