Load Cell 50kg to HX711

Other Hardware General Electronics
1

Hello!

I can't correct connect load cell 50kg sensor to HX711. I getting 0... Please help me.

Schemat in the attach.

Sketch

#include "hx711.h"
Hx711 scale(A2, A3);

// Connected A2 to DT
// and A3 to Clk

void setup() {
 Serial.begin(9600);
}

void loop() {
 Serial.print(scale.getGram(), 1);
 Serial.println(" g");
 delay(200);
}

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2

Possible issues:

  1. Your code appears to lack initialization and scaling configurations. Please post a link to the hx711 library being used.

  2. The two 1K resistors must be metal film, 1% tolerance. These resistors form the other half of a Wheatstone bridge. The initial ratio and long term stability of these two resistors determine the scale zero weight offset and stability of that zero. Trimming to true zero is most easily accomplished by placing a 10 turn, 50 ohm trimpot between the two 1K resistors with the pot wiper being the output.

3

avr_fred thank you for your answer.

I used this library:

I have only 1K ohm 5% tolerance resistors. Can't do this in any other way?

4

Hi,
If you have installed the library correctly, there should now be sample codes in the Example part of the IDE, under HX711.

Try the SerialScale code.

Load up one of those and use it as your template.

Tom... :slight_smile:

5

TomGeorge thank you for your answer.

I launched SerialScale code but the results still same. In the attach is serial port monitor.

Any ideas?

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6

Hi,
Okay now it time for you to DRAW your circuit, not the dritzy one, but reverse engineer what you have constructed.
Do it with pen/cil and paper, label your connections and post it please.

Also a picture of your project so we can see your component layout..

Have you got the HX711 connected to the correct pins, as noted in the example code?
Your fritzy shows A2 and A3, but I think the example uses different pins.

Thanks.. Tom... :slight_smile:

7

Ultra: do you have a digital voltmeter with a 200mv DC scale?

8

Hello!
TomGeorge and avr_fred thank you for your answer.

TomGeorge, in the attach is scheme and photos. I'm pleasure if you look.

TomGeorge:
Have you got the HX711 connected to the correct pins, as noted in the example code?
Your fritzy shows A2 and A3, but I think the example uses different pins.

I changed pins after load example code.

avr_fred, yes i have.

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9

I see 1% metal film resistors in your photos :wink:

Measure between A- (meter black lead) and A+ (meter red lead) on the HX711 board.

If the reading is a negative voltage, exchange the two 1k resistors. Measure again.
If the reading is more than +20mv (0.02 volts), you need better matched resistors or your load cell has a problem. If the load cell is suspected, pop the connector and measure resistance between white to black and white to red wires. Both resistances should be identical.

If the reading is between zero and no more than about +10 mv, the load cell side of the HX711 should be functional. Applying load to the load cell while measuring A+ to A- should increase the millivolt value. If that's all good, it's probably a software issue.

10

As shown in the photos, the object declaration should be:

Hx711 scale(A1, A0);
11

Ok I changed HX711 and it's work!

12

Hi,

I tried the configuration you made ... exactly tried to follow step by step but i only see the result 0. No matter what i do with the load cell.. Please help!

ultra:
Ok I changed HX711 and it's work!

How did you made it work?