Week 6General ·
After testing the sensor with oscilloscope we need to design the circuit to control it with the Arduino. since the capacitance is very small, we need a very fast processing. We checked the speed of the ADC of Arduino nano and it’s too slow for what we need. Tapio comes up with the idea of using the internal analog comparator of ATMEL microcontroller. We will read the time constant this way: firs we put a 5V voltage step on one sensor and we compare the one delayed by capacitance with a reference signal. the reference signal is tweaked in a way that exactly one tau is passed when the signal from the sensor becomes equal to the reference. This way we can use an interrupt driven by the comparator to calculate the time constant.
For us it was the first time we used a Milling machine. We faced some problem with scaling the output from Altium designer, but in the end we were able to start the milling process.
But we had a serious issue with the milling machine: the plane was not perfectly aligned so our PCB was not completely milled correctly. We tried multiple times to change and make deeper the z origin of the milling machine until we were able to get this not 100% perfect result.