What I wanted to learn, and why it interested me: I wanted to learn how to use the thermal receipt printers. I've seen these be used in interactive art pieces before but never knew how they worked or how I would integrate them into an Arduino build.   

Process and reflection: 

I am very, very surprised at how long this took me to set up. I had many more issues than I expected-- particularly with learning how to implement bitmaps. I also had to end up changing my final project because I couldn't get nested if/else statements to work with the printer. This is something I hope to get to work more on figuring out because I think it would be cool to make a "choose your own adventure" style game! But, I ended up getting to make my second favorite idea, which was using data from an input source and using the printer to visualize it. 

/*Zarmond D. Goodman (azarrill)

60-223 - Intro to Physical Computing

Fall 2025

References:

https://learn.adafruit.com/mini-thermal-receipt-printer/overview

https://courses.ideate.cmu.edu/60-223/f2025/tutorials/ultrasonic-ranger

  Arduino pin | role  | details

  ------------------------------

      6         input   Arduino transmit  YELLOW WIRE  labeled RX on printer

      5         input   Arduino receive   GREEN WIRE   labeled TX on printer

      A5        input   trigger pin on ultrasonic ranger

      A4        input   echo pin on ultrasonic ranger

      9         input   tactile pushbutton

*/

#include <Adafruit_Thermal.h>

#include <SoftwareSerial.h>

#include <NewPing.h>

#define TX_PIN 6 // Arduino transmit  YELLOW WIRE  labeled RX on printer

#define RX_PIN 5 // Arduino receive   GREEN WIRE   labeled TX on printer

#define TRIGGER_PIN  A5  // Arduino pin tied to trigger pin on the ultrasonic sensor.

#define ECHO_PIN     A4  // Arduino pin tied to echo pin on the ultrasonic sensor.

#define MAX_DISTANCE 350 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.

SoftwareSerial mySerial(RX_PIN, TX_PIN); // Declare SoftwareSerial obj first

Adafruit_Thermal printer(&mySerial);     // Pass addr to printer constructor

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.

const int BUTTONPIN = 9;

void setup() {

  pinMode(BUTTONPIN, INPUT_PULLUP);

  mySerial.begin(9600); // Initialize SoftwareSerial communication

  Serial.begin(115200); // Open serial monitor at 115200 baud to see ping results.

  printer.begin(); // Initialize printer

}

void loop() {

  int buttonState = digitalRead(BUTTONPIN);

  delay(50);                     // Wait 50ms between pings (about 20 pings/sec). 29ms should be the shortest delay between pings.

  int distance = sonar.ping_cm();

  Serial.print("Ping: ");

  Serial.print(distance); // Send ping, get distance in cm and print result (0 = outside set distance range)

  Serial.println("cm");

  if(buttonState == LOW) {

    if(distance > 20) {

      printer.println("you're a good distance away from me. stay there.");

      printer.println();

      printer.println();

      printer.println();

    } else {

      printer.println("girl, back up...");

      printer.println();

      printer.println();

      printer.println();

    }

  }

}