What I wanted to learn, and why it interested me: I wanted to learn how to transmit data and information across Arduinos so that they could communicate with each other. This interested me because it reminded me of the internet, the same way two separate devices with their own internal processes and data can still communicate data to each other.

Process and reflection: 

After completing the training sequence, my next step was the previously seen potentiometer to LED circuit. After that was finished, I focused on figuring out how to get the 8x8 LED display to work with one singular Arduino and creating patterns that I found interesting. From there, I attached it to the other Arduino with the "controller" attached to the transmitter and the display attached to the receiver. The most interesting part of the process was encoding the button presses through bit manipulation, where each button was represented by a single bit (on or off) and this 2 bit integer was sent to and understood by the receiver Arduino. From there, besides the max/min size problem displayed above, it was smooth sailing.

Overall I'm happy with how it came out. With more time I think I could've added more, maybe a moving circle or two Arduino's communicating back and forth with each other instead, but being able to use what I've learned in school with the bit manipulation was interesting enough for me.

/*

    60-223 Intro to Physical Computing, fall 2025

    Domain-specific Skill Building exercise: Transmitting Circles

    A sketch for transmitting the individual button presses of two buttons to another Arduino through the serial

    Pin mapping:

    Arduino pin | role  | details

    ------------------------------

8 input   button

7 input button

    Released to the public domain by the author, Sept 2025

    Helios Gayibor

*/

const int BUTTON1PIN = 8;

const int BUTTON2PIN = 7;

void setup() {

  Serial.begin(9600);

  pinMode(BUTTON1PIN, INPUT_PULLUP);

  pinMode(BUTTON2PIN, INPUT_PULLUP);

}

/*The prevButtons are to help make sure only one button press is registered by saving

the previous button state*/

bool prevButton1 = false;

bool prevButton2 = true;

void loop() {

  /*Get the button reads*/

  bool button1 = !digitalRead(BUTTON1PIN);

  bool button2 = !digitalRead(BUTTON2PIN);

  delay(20);

  /*If the prevButton was off and the new one is on, send a new message the to recieving

  arduino*/

  if ((!prevButton1 && button1) || (!prevButton2 && button2)) {

    /*This is weird, but we're encoding the values of button1 and button2 as a 2 bit integer

    for the receiver to unpack later:

    0      -> b1 off, b2 off

    1      -> b1 off, b2 on

    10 (2) -> b1 on, b2 off

    11 (3) -> b1 on, b2 on*/

    Serial.println(((button1 << 1) | (button2)));

    prevButton1 = button1;

    prevButton2 = button2;

  } else if (prevButton1 || prevButton2) {

    prevButton1 = false;

    prevButton2 = false;

  }

}

/*

    60-223 Intro to Physical Computing, fall 2025

    Domain-specific Skill Building exercise: Transmitting Circles

    A sketch for receiving the individual button presses of two buttons and increasing/decreasing the size of a displayed circle accordingly.

    Pin mapping:

    Arduino pin | role  | details

    ------------------------------

SCL output   8x8 display

SDA output 8x8 display

    Released to the public domain by the author, Sept 2025

    Helios Gayibor

*/

/*Libraries for the display*/

/*Credit for some of the display code to: https://www.hackster.io/wrightmac/arduino-uno-and-a-8x8-led-matrix-ht16k33-backpack-43e052 */

#include <Adafruit_LEDBackpack.h>

#include "Adafruit_GFX.h"      

Adafruit_8x8matrix matrix = Adafruit_8x8matrix();      

int r = 1; //Initial radius

void setup() {

  Serial.begin(9600);

  matrix.begin(0x70); //initalizing matrix        

}

void loop() {

  // when there is serial data waiting to be read

  while (Serial.available()) {

    //This is us decoding the buttons from the original encoding we made

    bool button1 = bool (Serial.parseInt() >> 1);

    bool button2 = bool (Serial.parseInt() & 0x1);

    //basic matrix set up

    matrix.setTextSize(1);      

    matrix.setTextColor(LED_ON);      

    matrix.clear();      

    matrix.setCursor(0,0);      

    // text to print      

    if (button1) {

      //decrease the radius if the button is pressed (up to 0)

      r = max(0, r-1);

    } else if (button2) {

      //increase the radius if the button is pressed (up to 4)

      r = min(r+1, 4);

    }

    Serial.println(r); //for testing

    //draw the circle in the center with the new radius

    matrix.drawCircle(4, 4, r, LED_ON);

    // write the data out to the matrix      

    matrix.writeDisplay();      

  }

}