I have been working on a new scale over the past few weeks. The scale has some major changes compared to the previous one:

• NAU7802 ADC instead of the HX711
• Two load cells instead of one
• Better mechanical stability/durability

The NAU7802 is a much improved Analog Digital Converter (ADC) compared to the HX711. Some of it's features include an I2C bus for configuration and reading values, two input channels and a build in (non calibrated) temperature sensor. The two load cells provide better mechanical stability for the scale but also make getting a weight value from the scale more complicated. At first I tried hooking up the load cells in parallel to a single channel of the NAU7802. That did not work out too well. The scale produced all sorts of values depending on where the weight was placed on the scale. The configuration I am using now hooks up each load cell to a dedicated channel of the NAU7802. I'm calibrating each load cell as an individual scale and then add up the two weight values to get the total weight on the scale. This is just like two people carrying an object and sharing the load. One person might be carrying more of the weight because the load is not equally balanced but if you add up the weight each person is carrying you end up with the total weight of the object. And last but not least I have added a rim to the scale weight plate. This should make it harder for nesting material to clog up the scale.