Input Devices

Continuing the theme of preparing for my final project, I wanted to test pressure sensors this week as a precursor to building my smart punching bag. To start, I modified Quentin Bolsee's fabulous SAMD21E17A DevKit design to set up the analog pins as voltage dividers, adding one of the 5 mega ohm resistors Nathan had recommended I try for the punching bag.

After milling and soldering the board (adding one small jumper for a missed trace between the header pin and the SAMD) I bootloaded using EDBG and attached the velostat sensor. At first I got a lot of random noise, but then realized the pin mapping into Arduino was not as straightforward as previously assumed, so referred to Quentin's documentation to get the right pin assignment. Rob and I also did some multimeter checks which revealed that my resistor was way too large, especially given the size of the pad created with copper tape, so adjusting down to 100 ohms helped a lot. With a functional sensor, I placed it on a styrofoam box I'd made to test the dimensions of the final project, and it worked well even under the soft foam! Check out the final page for more details on how this input method was then replicated and programmed in sequence.