HX711

[alizare368]

Hi
I designed a board for weight measurement  with load cell sensor and using HX711 for high accuracy.

How can I calibrate it for milligram(mg)? 

[agehall]

"Maybe" is about as accurate answer to this question as you can expect to get.

The HX711 is, from what I can tell just the ADC, not the load cell. So we would need to know the performance of your load cell before anyone can help you figure out what the maximum resolution of your system would be.

[ali_asadzadeh]

what's your loadcell size? do you have any circuit or sample program to share?

[Wiljan]

The way to calibrate are simple read data from HX711 without any weight this data are your Zero weight "0.000"
Now add a known load on your cell like 1 kg or 1 Pound or 1 Brick or whatever you want to measure in you will get a new value
This new value - the zero value are now = to 1Kg or what you want to measure in
Now it pressy simple math to convert any value to a weight 

I assume you use  Arduino, but if not it's the same way to do it
Have a look here how to connect weightcells to the  HXD711
https://learn.sparkfun.com/tutorials/load-cell-amplifier-hx711-breakout-hookup-guide

in the bottom there are links to 2 software, 1 for calibrate and 1 for readout

If you run the calibrate software you can inc / dec the calibration value so your weight fits the actually load
 
Hope it helps

[alizare368]

Hi
The output of ADC(hx711) sample code contract in txt file.
How can I stable the output?

[alizare368]

the c code Reference Driver（C）contract in txt file.

[alizare368]

"Maybe" is about as accurate answer to this question as you can expect to get.

The HX711 is, from what I can tell just the ADC, not the load cell. So we would need to know the performance of your load cell before anyone can help you figure out what the maximum resolution of your system would be.

Hi
The output of ADC(hx711) sample code contract in txt file.
How can I stable the output?

[Wiljan]

When you read the ADC with so sensitive signals it will variate, you will need to add in a filter so you do an average eg over 25 samples
there are plenty of examples on the internet to do "average filtering"
What chip / board do you use for your c code?

[iMo]

You may try this simple filter:

double new_value, old_value;
double k = 0.05;    // the smaller "k" the more filtering
                            // k is usually from 0.2 to 0.01, k< 1.0
old_value = 0.0;    // or something else, ie. 8374000.0
..
new_value = k * (double)ReadCount() + ((1.0 - k) * old_value);
// here you may print the new_value..
old_value = new_value;
..

[alizare368]

STM32f030k6t

[alizare368]

When you read the ADC with so sensitive signals it will variate, you will need to add in a filter so you do an average eg over 25 samples
there are plenty of examples on the internet to do "average filtering"
What chip / board do you use for your c code?

STM32f030k6t