HX711 load cell ESP8266

Hi there

I am trying to build a scale with the following components:

ESP8266 aka Wemos D1 mini
HX711
Load cell https://www.sparkfun.com/products/10245

I followed this tutorial where I used the below wiring from the right side of the HX711 and D1.
Bildschirmfoto 2022-06-04 um 01.30.37

I plan to only use one cell and used the wiring below between the load cell and HX711 (50kg Load Cells with HX711 and Arduino. 4x, 2x, 1x Diagrams. - Circuit Journal)

Unfortunately it doesnt seem to work, I cant get Arduino IDE to work in order to do the calibration.

question
has anybody knowledge how I could realize this with ESPHome and may help with the wiring? I have basic knowledge with ESPHome but not any with wiring load cells. I spent hours of research but couldnt find any suitable tutorial with my config including only one cell. for example I found this thread: ESP8266 + HX711 + 4 small load cells giving incorrect values

The goal is to use the scale for a “smart” toilet paper holder :wink:

all the best

Andrew

The wires colors on load cells are not always correct. With a resistance meter, a pair will be 2x the resistance. That pair should be the e- and e+ in your diagram

many thanks for the quick reply. I measured the resistance and as per 50kg Load Cells with HX711 and Arduino. 4x, 2x, 1x Diagrams. - Circuit Journal I have 1K between red and white or red and black.

this is how my code with ESPHome looks like:

esphome:
  name: loadcell

esp8266:
  board: d1_mini

# Enable logging
logger:

# Enable Home Assistant API
api:

ota:
  password: "XX"

wifi:
  ssid: 'XX'
  password: 'XX'

# Example configuration entry
sensor:
  - platform: hx711
    name: "HX711 Value"
    dout_pin: D1
    clk_pin: D2
    gain: 128
    update_interval: 2s
    

the log always shows a value of 0 regardless how much pressure I put on the sensor. I even tried another HX711 and another load cell (also checked the resistance) but have the same results.

I tried this config here: HX711 Load Cell Amplifier — ESPHome

detailed wiring:

I use the full four load cells and never tried with less. The only thing I might suggest is trying with all 4 load cells to first make sure that the items you have are working.

thats a good idea, actually it doesnt work either :S I have no clue what I am doing wrong but I will put it aside for the moment :stuck_out_tongue: I never had issues with other ESP-projects. If I find a solution I will post it here.

This is the guide I used

https://learn.sparkfun.com/tutorials/getting-started-with-load-cells

2 Likes

salut andré
perso j’ai eu quelque souci aussi mais j’ai pris des risque et ça a payé.
j’ai une seul cellule de charge de 200kg et en faite les couleur sont :
rouge = v+
vert = v-
blanc = e-
noir = e+
rien a y comprendre mais ça a fonctionner pour moi .
bonne chance!

Hi, did you ever get this to work??

Did you manage to make one sensor work?

not really, I switched to a FSR-sensor FSR - the best bed occupancy sensor - #9 by tom_l which works awesome! give it a try, it easy to setup and very reliable.

For future reference: there are “single” load-cells with 4 internal sensors aka beam load-cells and these will plug straight into the HX711 (and have more wires).

The sensor that was being used must be configured as part of 4 into a Wheatstone bridge - Wikipedia or it simply won’t work; the HX711 is (from memory) measuring tiny tiny voltage differences and needs the cancellation and comparison effect of this bridge (which is a bit of a mind-bender in itself, and look how old it is)

Also the stamped metal sensor being used here is a bit …terrible (I have some). Its poor measurement repeatability and creep under load will be annoying, I’d suggest a cheap beam sensor is 10x better and simpler at the same time.