Very simple holder for HX711 load cells, to be installed under bed mattress. it is holding by two screws with washers.

Main motivation was to be able to run automations like turn off all lights and open blinds in the morning. Overall it came out surprisingly exact, as whole mattress became giant scale. The build should be under 10 €. HX711 with 4 load cells, Wemos D1 mini, and 3D printed mounts. Flashed with ESPHome.

Device itself is connected by scheme attached, and wired to Wemos D1 mini through I2C

Shopping list

HX711 Load cells Wemos D1 Mini Telephone 4 wire cable Telephone 4 pin connectors I had laying around.

Bellow is firmware for ESPhome to use it with HomeAssistant. After installing you have to look for logs, mark the number sensing with no weight, and then put some known weight and again mark this number from sensors even if it's negative. Then put these numbers as calibration filter bellow.

```yaml substitutions: devicename: "smart_scale" upper_devicename: "Smart scale"

esphome: name: $devicename platform: ESP8266 board: d1_mini

wifi: networks:

ssid: "IoT-WiFi" password: !secret Luc3as_IOT_WIFI_PASS #manual_ip:

static_ip: 192.168.3.123

gateway: 192.168.3.1

subnet: 255.255.255.0

dns1: 192.168.3.1

ap: ssid: ${upper_devicename} AP password: "password"

captive_portal:

Enable logging

logger: #level: debug

Enable Home Assistant API

api: password: !secret esphome_api_pass

ota: password: !secret esphome_ota_pass

text_sensor:

platform: template name: ${upper_devicename} uptime lambda: |- uint32_t dur = id(uptime_s).state; int dys = 0; int hrs = 0; int mnts = 0; if (dur > 86399) { dys = trunc(dur / 86400); dur = dur - (dys * 86400); } if (dur > 3599) { hrs = trunc(dur / 3600); dur = dur - (hrs * 3600); } if (dur > 59) { mnts = trunc(dur / 60); dur = dur - (mnts * 60); } char buffer[17]; sprintf(buffer, "%ud %02uh %02um %02us", dys, hrs, mnts, dur); return {buffer}; icon: mdi:clock-start update_interval: 30s

sensor:

platform: uptime id: uptime_s update_interval: 30s
platform: wifi_signal name: ${upper_devicename} WiFi Signal update_interval: 60s
platform: hx711 name: "Weight" dout_pin: D1 clk_pin: D2 gain: 128 update_interval: 30s
filters:
- calibrate_linear:
  - 7711 -> 0
  - -156518 -> 79.5 unit_of_measurement: kg

switch:

platform: restart name: ${upper_devicename} restart ```

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