How to convert ADC value to weight

[KlausST]

Hi,

Maybe you have a too low input voltage.

Tell us the sensor output voltage range and the ADC input voltage range.

Klaus

 

[paulfjujo]

hello,


Are you using the analog supply register => means Load cell supply < 5V
If your load cell is supllyed by 5V
you will get 5x2= 10mV for the full scale of load cell (40Kg)
Your ADC 24 bits with a Gain of 128 => +-23 bits for +-40mV
so resulting max resolution could be +-21 bits to represente +-10mV
if unipolar way 21bits for 10mV ,
large enough 4 194 304 points -> 40 000 grammes. for your request..

But...
This king of ADC have a very low SPS .. minima is 10 SPS , or in your application you use delay of 1 µS ..
Except for Sclk status 1 , wich must be less than 50µS ( to avoid the device going in sleep mode)
i think you must use some delay (any mS ) bewteen conversions to respect the 10 SPS..
Also you must average many elementary measure ( 8 to 16 measures) to get a usefull average
before to transform it in weight..

before transforming in weight.. check to get a stable RAW measure ..

you also can test your ADC measure chain, by using a potar 50 ohms to simulate Load cell input.
example +-23mV