08 Input Devices
This week I made a capactitve touchpad with an ATTiny1624 microcontroller, which measures input voltage on four pads using multitouch step-response.
Tools: Fusion360, PCB Milling Machine, Soldering Irons, Arduino, Python
VIDEO
Circuit Design
I have taken as reference Neil's example,
in which he uses a voltage divider to measure the differences between two parallel
capacitive plates separated by a non-capacitive material.
My design has four capacitive plates, so I have placed four outputs, one for each of the plates.
The input here will be the capacitive plate,
with respect to which I measure the difference in capacitance of the other four.
![](images/week8/02.jpeg)
![](images/week8/03.jpeg)
Once the PCB is designed, I milled the blank red cooper PCB and soldered on the components, and following used my UPDI programmer to program the ATTiny1624.
![](images/week8/07.jpeg)
![](images/week8/08.jpeg)
Touchpad design and Programming
![](images/week8/09.jpeg)
The input capacitive plate is located below the other four, with a size that cover the four with inset of a few mm. See here the back oh the house!
![](images/week8/10.jpeg)
Even thought I was receiving four different values, they were floating voltages values.
I think that the connection of the input pin with Ground was not working for me.
The pin was very loose on the PCB because I had drawn the paths between components too fine (.15 mm)-- next time drawing them at least .3 mm.
![](images/week8/11.jpeg)
Once this was fixed, I uploaded the program, and it worked!
![](images/week8/12.jpeg)
I used as a reference Neil's step response-code and Miana's.
![](images/week8/13.jpeg)