This week, we learned about ATtiny85, created a jig (to upload code from an Arduino) on a perfboard, and made a sensor-LED application. ATtiny85 is an 8-bit AVR microcontroller that comes with 8-pin interface. It can use Arduino code and can operate on minimum power (3V-5V).
For my application, I decided to do a capacitive touch LED circuit. To my surprise, ATtiny can also use Arduino Libraries?!! I uploaded an old sketch using the CapacitiveSensor.h library, and it worked great.
Adding some very basic animation (using delay), a button on the Reset (Pin 1), and a coin battery, I have a circuit:
Code below:
#include <CapacitiveSensor.h>
CapacitiveSensor capTouch = CapacitiveSensor(3, 4);
int ledPin = 0;
int ledPin2 = 1;
int ledPin3 = 2;
boolean secondState = false;
// smoothing
const int numReadings = 10;
long total1;
int readings[numReadings];
int readIndex = 0;
int total = 0;
int average = 0;
void setup(){
capTouch.set_CS_AutocaL_Millis(0xFFFFFFFF); // turn off autocalibrate on channel 1 - just as an example
pinMode(0, OUTPUT);
pinMode(1, OUTPUT);
pinMode(2, OUTPUT);
for (int thisReading = 0; thisReading < numReadings; thisReading++)
readings[thisReading] = 0;
}
void loop(){
long start = millis();
total1 = capTouch.capacitiveSensor(30);
delay(10);
smooth();
if (average >= 15){
digitalWrite(0, 1);
delay(15);
digitalWrite(1, 1);
delay(15);
digitalWrite(2, 1);
delay(1);
} else {
digitalWrite(2, 0);
delay(15);
digitalWrite(1, 0);
delay(15);
analogWrite(0, 0);
}
}
// smooth code I stole from somewhere a while ago
void smooth() {
// subtract the last reading:
total = total - readings[readIndex];
// read from the sensor:
readings[readIndex] = total1;
// add the reading to the total:
total = total + readings[readIndex];
// advance to the next position in the array:
readIndex = readIndex + 1;
// if we're at the end of the array...
if (readIndex >= numReadings)
// ...wrap around to the beginning:
readIndex = 0;
// calculate the average:
average = total / numReadings;
// send it to the computer as ASCII digits
}I also went a bit extra and made it into a circuit sculpture. It was… challenging because the legs are so close together. My soldering was also not the best, because I was impatient and didn’t plan well — BUT IT WORKED! It’s not always very stable; there’s probably some connection issue with the battery.
Definitely more circuit sculpture coming this semester — learning about the cheap alternative mini-chip is giving me a lot of ideas…
