I want to connect the load cell of my (micro) scale to my Arduino. The scale itself is able to weigh max. 800 grams with an accuracy of 0.1 grams - what I want to weigh are loads up to max. 100 grams, with the same accuracy of 0.1 grams.
I've de-soldered the load cell and attached it to the INA125P amplifier using this setup: http://cdn.instructables.com/FNY/02KS/HFSH4TQO/FNY02KSHFSH4TQO.MEDIUM.jpg
When I try to read values using analogRead(), the scale seems to work - however, the first value that I get from analogRead without any weight on the load cell is around ~480 - when I put 100g weight on it, the value goes up to 866 - and won't go any further, even if I put more than 100g weight on it.
I've tried to replace the 10 Ohm Resistor with a 47 Ohm Resistor. analogRead then returned ~106 as "start value" without a weight on it, and a value of 270 with the 100gram weight on. However, since I want to be able to weigh loads with an accuracy of 0.1 gram, the 47 Ohm resistor doesn't seem a solution to me.
Basically, my question is: Is there a way to get the accuracy that I want? Is there a way to reduce the "start value" of 480 to a value around 10? Since I've nearly no knowledge about electrical engineering, I'd be glad if somebody could help me with a newbie-friendly answer.
Thank you very much in advance.