Input Devices/ Depths and Limits

This week I wanted to test two systems that would allow me to track the plunger depth of my extruder: a capacitive sensor that I could to measure relative distance and limit switches that will mark the boundaries of the plunger travel distance. Both inputs will eventually communicate with the solid state relay and turn the pump on and off according to how mucht the plunger has plunged, which indicates the volume that has been evacuated from the extruder and simultaneously how much needs to be pumped back in for it to reach capacity. I put these new inputs on the same board as my outputs for my solid state relay, got rid of the resonator, and changed the loction of the LED so I could continue to test functionality with basic scripts.

I had some difficulty programming the board as I didn't realize how much I had to change the code I inherited from Neil's loading board and Matt's Touchpad. After changing the inputs and outputs pins, the make file, and bit shifting values, I finally got a reading on the oscilloscope, which indicated that the "touchpad" was acting as a capacitor and affecting the charging of the board.

I also had difficulty loading Neil's Python script on to my computer. I had all of the necessary software downloaded but when I loaded the script, it printed that it was running, but did not open the GUI. The script was working on the desktop in the lab so I used it there, but was not sure if the fluctuations correlated with what I was seeing on the oscilloscope, specifically because the changes were so small and happened after considerable delays.

I also tested the limit switches but could not get them to trigger the LED. I test the inputs with the multimeter and all of the connections were working so I think it was something to do with the program that I was uploading and the loop of on/off commands. I'll continue to work on this for the final project and also might experiment with a slide potentiometer as an alternative to the touchpad distance sensor.