For our first prototype we fed the output of our two load cell wheatstone bridge into the Delsig ADC of our psoc 5lp board. The white and black wires of the cells go to Power (5V) and GND, while the red wires get measured by the ADC in this configuration. The ADC supports several inputs, as well as allowing adjustment of the gain of our input, allowing us to boost the load cell output to usable levels. The first picture shows how the load cells are connected in psoc creator, while the second one shows our current ADC configuration.

Once the psoc has read the value, we convert it to a value in ounces. When the psoc is first booted up, it will be calibrated with the value of a full 40. Then the current ounce value is continuously measured. Whenever the drink is removed from the coaster, it will pause updating the value (it will measure a value below 0 ounces when you’re drinking) until the value returns to at least 0 ounces. Right now we have the output sent over serial usb to a terminal on the computer. In the future we will use HID output instead to appear as a game controller, so the coaster can work in any game.

We'll go over USB HID and the programming soon, as well as the creation of the Killing Floor game mod.