Interface is the way to communicate through the eyes of the user, on this assignment I will try to implement it and Program an Application that converts input to screen visualization.

For this week I wanted to demonstrate an input from two photoresistors for my final project. I used a board that I made a few weeks earlier and programmed it to send the readings through the serial port.

Serial communication needs a special library for the AtTiny44 micro-controller. I used the SoftwareSerial.h after downloading the .zip file I opened the Sketch menu->Include Library->Add .ZIP Library and browsed to the downloaded zip file.

This is the code I wrote for the input controller. Using SoftwareSerial I declared pins 0 and 1 as Rx and Tx, pin 0 receives data from the computer and pin 1 transmits. The controller waits for a signal from the serial monitor and then reads the input from the two photoresistors and sends back the readings.

#include <SoftwareSerial.h> SoftwareSerial mySerial(0, 1); // RX, TX on pins 0 and 1 of AtTiny44 int firstSensor = 0; // first analog sensor int secondSensor = 0; // second analog sensor int inByte = 0; // incoming serial byte void setup() { mySerial.begin(9600); pinMode(2, INPUT); // first photoresistor on pin 2 pinMode(3, INPUT); // second photoresistor on pin 3 } void loop() { // commit readings when triggered by serial port: if (mySerial.available() > 0) { firstSensor = analogRead(2); // delay 10ms to recover: delay(10); // read second analog input secondSensor = analogRead(3); // send sensor values: mySerial.write(firstSensor); mySerial.write(secondSensor); } }

To program the controller I used Arduino as ISP. In the examples there is a program that I uploaded to my Arduino UNO. After I uploaded the code, I connected it to the 6 pin connector as written below.

// pin name: not-mega: mega(1280 and 2560) // slave reset: 10: 53 // MOSI: 11: 51 // MISO: 12: 50 // SCK: 13: 52 // VCC: 5V: 5V // GND: GND: GND

For the application that interfaces the input I used Processing. I found it very intuitive and easy to work with. The interface is very similar to Arduino and the code structure is also not so different.

I wrote a code that draws an ellipse on the screen according to the input of both sensors. The first photoresistor determines the X axis position and the second photoresistor determines the Y axis position. This is the code.

import processing.serial.*; Serial myPort; // The serial port int[] serialInArray = new int[2]; // Where we'll put what we receive int serialCount = 0; // A count of how many bytes we receive int xpos, ypos; // Starting position of the ball boolean firstContact = false; // Whether we've heard from the microcontroller void setup() { size(256, 256); // Stage size noStroke(); // No border on the next thing drawn // Set the starting position of the ball (middle of the screen) xpos = width/2; ypos = height/2; println(Serial.list()); String portName = Serial.list()[0]; myPort = new Serial(this, portName, 9600); } void draw() { background(255); fill(0); // Draw the ellipse ellipse(xpos, ypos, 20, 20); } void serialEvent(Serial myPort) { // read a byte from the serial port: int inByte = myPort.read(); // if this is the first byte received, and it's an A, // clear the serial buffer and note that you've // had first contact from the microcontroller. // Otherwise, add the incoming byte to the array: if (firstContact == false) { if (inByte == 'A') { myPort.clear(); // clear the serial port buffer firstContact = true; // you've had first contact from the microcontroller myPort.write('A'); // ask for more } } else { // Add the latest byte from the serial port to array: serialInArray[serialCount] = inByte; serialCount++; // If we have 3 bytes: if (serialCount > 2 ) { xpos = serialInArray[0]; ypos = serialInArray[1]; xpos = map(xpos, 50, 550, 1, 256); ypos = map(ypos, 50, 550, 1, 256); // Send a capital A to request new sensor readings: myPort.write('A'); // Reset serialCount: serialCount = 0; } } }