Very different values for load cell with hx711 converter

Mausbiber · September 4, 2022, 10:57pm

Hi,

I am trying to build a scale for an aquarium (I want to find out how much water evaporates) using 4 x load cells and a HX711 ADC converter.
I followed this example for the wiring (I have the same load cells as in the link):

https://github.com/markusressel/ESPHome-Smart-Scale

Now I have followed the example code in the esphome docs and I already get values back.
At least a success

Here is my code:

sensor:
  - platform: dallas
    address: 0xee00000006ffb128
    name: "Aquarium Temperature"
    
  # RAW Scale input
  - platform: hx711
    name: "Aquarium Gewicht"
    id: smart_scale_hx711_value_raw
    dout_pin: GPIO16
    clk_pin: GPIO17
    gain: 128
    unit_of_measurement: kg
    accuracy_decimals: 3
    update_interval: 1s

Next I wanted to calibrate the whole thing as indicated in the esphome docs.
But I can’t get any further here.

I have connected the 4 x load cells as described in the link and there is no weight at all, but I still get different raw values all the time.

Here is what the log says:

[23:13:27][D][hx711:031]: 'Aquarium Gewicht': Got value 142727
[23:13:27][D][sensor:127]: 'Aquarium Gewicht': Sending state 142727.00000 kg with 3 decimals of accuracy
[23:13:28][D][hx711:031]: 'Aquarium Gewicht': Got value 142691
[23:13:28][D][sensor:127]: 'Aquarium Gewicht': Sending state 142691.00000 kg with 3 decimals of accuracy
[23:13:29][D][hx711:031]: 'Aquarium Gewicht': Got value 142741
[23:13:29][D][sensor:127]: 'Aquarium Gewicht': Sending state 142741.00000 kg with 3 decimals of accuracy
[23:13:29][D][api:102]: Accepted ::FFFF:C0A8:7FFE
[23:13:30][D][api.connection:861]: Home Assistant 2022.8.7 (::FFFF:C0A8:7FFE): Connected successfully
[23:13:30][D][hx711:031]: 'Aquarium Gewicht': Got value 142719
[23:13:30][D][sensor:127]: 'Aquarium Gewicht': Sending state 142719.00000 kg with 3 decimals of accuracy
[23:13:31][D][hx711:031]: 'Aquarium Gewicht': Got value 142671
[23:13:31][D][sensor:127]: 'Aquarium Gewicht': Sending state 142671.00000 kg with 3 decimals of accuracy
[23:13:32][D][hx711:031]: 'Aquarium Gewicht': Got value 142706
[23:13:32][D][sensor:127]: 'Aquarium Gewicht': Sending state 142706.00000 kg with 3 decimals of accuracy
[23:13:33][D][hx711:031]: 'Aquarium Gewicht': Got value 142632
[23:13:33][D][sensor:127]: 'Aquarium Gewicht': Sending state 142632.00000 kg with 3 decimals of accuracy
[23:13:34][D][hx711:031]: 'Aquarium Gewicht': Got value 142580
[23:13:34][D][sensor:127]: 'Aquarium Gewicht': Sending state 142580.00000 kg with 3 decimals of accuracy
[23:13:35][D][hx711:031]: 'Aquarium Gewicht': Got value 142630
[23:13:35][D][sensor:127]: 'Aquarium Gewicht': Sending state 142630.00000 kg with 3 decimals of accuracy
[23:13:36][D][hx711:031]: 'Aquarium Gewicht': Got value 142619
[23:13:36][D][sensor:127]: 'Aquarium Gewicht': Sending state 142619.00000 kg with 3 decimals of accuracy
[23:13:37][D][hx711:031]: 'Aquarium Gewicht': Got value 142586
[23:13:37][D][sensor:127]: 'Aquarium Gewicht': Sending state 142586.00000 kg with 3 decimals of accuracy
[23:13:38][D][hx711:031]: 'Aquarium Gewicht': Got value 142667
[23:13:38][D][sensor:127]: 'Aquarium Gewicht': Sending state 142667.00000 kg with 3 decimals of accuracy
[23:13:39][D][hx711:031]: 'Aquarium Gewicht': Got value 142539
[23:13:39][D][sensor:127]: 'Aquarium Gewicht': Sending state 142539.00000 kg with 3 decimals of accuracy
[23:13:40][D][hx711:031]: 'Aquarium Gewicht': Got value 142599
[23:13:40][D][sensor:127]: 'Aquarium Gewicht': Sending state 142599.00000 kg with 3 decimals of accuracy
[23:13:41][D][hx711:031]: 'Aquarium Gewicht': Got value 142565
[23:13:41][D][sensor:127]: 'Aquarium Gewicht': Sending state 142565.00000 kg with 3 decimals of accuracy
[23:13:42][D][hx711:031]: 'Aquarium Gewicht': Got value 142529
[23:13:42][D][sensor:127]: 'Aquarium Gewicht': Sending state 142529.00000 kg with 3 decimals of accuracy
[23:13:43][D][hx711:031]: 'Aquarium Gewicht': Got value 142524
[23:13:43][D][sensor:127]: 'Aquarium Gewicht': Sending state 142524.00000 kg with 3 decimals of accuracy
[23:13:44][D][hx711:031]: 'Aquarium Gewicht': Got value 142535
[23:13:44][D][sensor:127]: 'Aquarium Gewicht': Sending state 142535.00000 kg with 3 decimals of accuracy
[23:13:45][D][hx711:031]: 'Aquarium Gewicht': Got value 142517
[23:13:45][D][sensor:127]: 'Aquarium Gewicht': Sending state 142517.00000 kg with 3 decimals of accuracy
[23:13:46][D][hx711:031]: 'Aquarium Gewicht': Got value 142574
[23:13:46][D][sensor:127]: 'Aquarium Gewicht': Sending state 142574.00000 kg with 3 decimals of accuracy
[23:13:47][D][hx711:031]: 'Aquarium Gewicht': Got value 142515
[23:13:47][D][sensor:127]: 'Aquarium Gewicht': Sending state 142515.00000 kg with 3 decimals of accuracy
[23:13:48][D][hx711:031]: 'Aquarium Gewicht': Got value 142527
[23:13:48][D][sensor:127]: 'Aquarium Gewicht': Sending state 142527.00000 kg with 3 decimals of accuracy
[23:13:49][D][hx711:031]: 'Aquarium Gewicht': Got value 142562
[23:13:49][D][sensor:127]: 'Aquarium Gewicht': Sending state 142562.00000 kg with 3 decimals of accuracy
[23:13:50][D][hx711:031]: 'Aquarium Gewicht': Got value 142508
[23:13:50][D][sensor:127]: 'Aquarium Gewicht': Sending state 142508.00000 kg with 3 decimals of accuracy
[23:13:51][D][hx711:031]: 'Aquarium Gewicht': Got value 142530
[23:13:51][D][sensor:127]: 'Aquarium Gewicht': Sending state 142530.00000 kg with 3 decimals of accuracy
[23:13:52][D][hx711:031]: 'Aquarium Gewicht': Got value 142508
[23:13:52][D][sensor:127]: 'Aquarium Gewicht': Sending state 142508.00000 kg with 3 decimals of accuracy
[23:13:53][D][hx711:031]: 'Aquarium Gewicht': Got value 142544
[23:13:53][D][sensor:127]: 'Aquarium Gewicht': Sending state 142544.00000 kg with 3 decimals of accuracy
[23:13:54][D][hx711:031]: 'Aquarium Gewicht': Got value 142518
[23:13:54][D][sensor:127]: 'Aquarium Gewicht': Sending state 142518.00000 kg with 3 decimals of accuracy
[23:13:55][D][hx711:031]: 'Aquarium Gewicht': Got value 142501
[23:13:55][D][sensor:127]: 'Aquarium Gewicht': Sending state 142501.00000 kg with 3 decimals of accuracy
[23:13:56][D][hx711:031]: 'Aquarium Gewicht': Got value 142525
[23:13:56][D][sensor:127]: 'Aquarium Gewicht': Sending state 142525.00000 kg with 3 decimals of accuracy
[23:13:57][D][hx711:031]: 'Aquarium Gewicht': Got value 142504
[23:13:57][D][sensor:127]: 'Aquarium Gewicht': Sending state 142504.00000 kg with 3 decimals of accuracy
[23:13:58][D][hx711:031]: 'Aquarium Gewicht': Got value 142535
[23:13:58][D][sensor:127]: 'Aquarium Gewicht': Sending state 142535.00000 kg with 3 decimals of accuracy
[23:13:59][D][hx711:031]: 'Aquarium Gewicht': Got value 142555
[23:13:59][D][sensor:127]: 'Aquarium Gewicht': Sending state 142555.00000 kg with 3 decimals of accuracy
[23:14:00][D][hx711:031]: 'Aquarium Gewicht': Got value 142575
[23:14:00][D][sensor:127]: 'Aquarium Gewicht': Sending state 142575.00000 kg with 3 decimals of accuracy
[23:14:01][D][hx711:031]: 'Aquarium Gewicht': Got value 142577
[23:14:01][D][sensor:127]: 'Aquarium Gewicht': Sending state 142577.00000 kg with 3 decimals of accuracy
[23:14:02][D][hx711:031]: 'Aquarium Gewicht': Got value 142608
[23:14:02][D][sensor:127]: 'Aquarium Gewicht': Sending state 142608.00000 kg with 3 decimals of accuracy
[23:14:03][D][hx711:031]: 'Aquarium Gewicht': Got value 142667
[23:14:03][D][sensor:127]: 'Aquarium Gewicht': Sending state 142667.00000 kg with 3 decimals of accuracy
[23:14:04][D][hx711:031]: 'Aquarium Gewicht': Got value 142674
[23:14:04][D][sensor:127]: 'Aquarium Gewicht': Sending state 142674.00000 kg with 3 decimals of accuracy
[23:14:05][D][hx711:031]: 'Aquarium Gewicht': Got value 142793
[23:14:05][D][sensor:127]: 'Aquarium Gewicht': Sending state 142793.00000 kg with 3 decimals of accuracy
[23:14:06][D][hx711:031]: 'Aquarium Gewicht': Got value 142834
[23:14:06][D][sensor:127]: 'Aquarium Gewicht': Sending state 142834.00000 kg with 3 decimals of accuracy
[23:14:07][D][hx711:031]: 'Aquarium Gewicht': Got value 142847
[23:14:07][D][sensor:127]: 'Aquarium Gewicht': Sending state 142847.00000 kg with 3 decimals of accuracy
[23:14:08][D][hx711:031]: 'Aquarium Gewicht': Got value 142891
[23:14:08][D][sensor:127]: 'Aquarium Gewicht': Sending state 142891.00000 kg with 3 decimals of accuracy
[23:14:09][D][hx711:031]: 'Aquarium Gewicht': Got value 142935
[23:14:09][D][sensor:127]: 'Aquarium Gewicht': Sending state 142935.00000 kg with 3 decimals of accuracy

All these different values within 1 minute and there is no weight at all.
Why is this?
If the values are so extremely different, how can I calibrate the whole thing reasonably?
Above all, which of the many raw values do I use for 0 kg?

Mausbiber · September 5, 2022, 11:35pm

Can anyone tell me if the changing values are normal, or what I can do about it?

Mausbiber · September 11, 2022, 2:47pm

First chart is 0kg & Temp
Second is 20.65 kg & Temp

finity · September 11, 2022, 4:03pm

I’ve noticed my sensors are temperature sensitive as well.

I have one set of sensors sandwiched between two PVC (plastic) boards and one set between PVC and steel and the one on the steel is more sensitive than the other. I think it’s because the steel is less of an insulator than the PVC and it has a bigger effect on the temperature of the sensor itself.

Mausbiber · September 11, 2022, 4:34pm

I thought so too, which is why I have also shown the temperature in the charts.
And I don’t see any relation between the temperature curve and the values from the load cell.