This week my main task was to assemble the circuit that would maximize the voltage range output for the flex sensors. We faced the issue where we wanted to use a full 5V range by supplying 5V to each flex sensor, having its voltage output go through an opAmp, and maximizing the range output. The issue we found was that the Arduino Nano BLE Sense Rev2 may be able to supply ~5V (through the computer via USB), but it first of all ranges between 4.5-5.5V and the analog input pins cannot read more than 3.3V because the operating voltage for the Nano is 3.3V. This is an inherent characteristic of the Arduino Nano which is why we cannot reach the full 5V range and we will have to maximize the range to 3.3V. By creating a simple circuit with an operational amplifier, we managed to get a range of 0-2.8V to ensure we don’t max out the ADC. We realistically don’t get near 0 V but getting as close to it as possible diversifies our input as much as possible to give our ML model a good chance at classifying well. We used a simple non inverting amplifier to implement this.
I also soldered wires to our flex sensors to make it easy to connect them to our breadboard. I also cleaned up the circuit we initially made to prevent shorting any connections and making it easier to debug. I also wrote the Arduino script to receive data from the flex sensors and IMU as we were assembling the glove.