week10 : input devices

Assignment: Make a board to read sensors.

First I was thinking about my final project and what the best way for reading movements of the doll's head and arms are. Last year, I studied capasitive sensors for the research, so I know some tips. I think, however, to use capasitive sensor for reading movements of the doll is not good because it depends on the pressure of fingers. I'd like to read the exact position of doll's arms and head, so for final project, I wanna use the magnetic fields.

Anyway, at FabLabBarcelona we ordered the sensors late, so we couldn't get any sensros until Monday. Therefore I made the main board with Attiny44 for 3 three inputs first, then I made a mini board for capasitive sensor. I saw the data sheet of Attiny44 and there are 8 pins for inputs. I used 2 pins as the serial communication and rest pins for inputs. Also there is a pin for only pwm output, so I connected it to LED. The schematic is here.

The process of making the board is same as the electronics design week. I just changed the components from button to 2 pins. Actually some pins are shared with inputs and for FabISP, so when I write the code to the board, I need to unplug the modules. Here is the result.

At the mini board, I put a 1M orm resistor. When the person touches the copper, the person becomes as the capasitor and the input can read the value of the capasitor.

The result. When I touch the copper, the LED blinks and the computer reads the value (but it's unstable like 10 ~ 960 randamly). On the other hand, when I don't touch it, the LED doesn't blink and the computer reads "1" as the value. I used Arduino for programming first, now I'm trying to use C code, if it works, I will add the description.

Download links

Eagle: Analog Read board Analog read schematics touch board touch schematics

Analog Read Trace Analog Read cutout

touch trace touch cut

Programs: c make python