@lachlanjcIMA @ NYU

CC – Week 6: Connection – Project

This week we’re using a combination of p5.js & the Arduino hardware to make something. I got inspired by the auto-brightness functionality on my laptop/devices—it automatically senses ambient light, then dynamically, subtly adjusts my screen brightness in the background.

Let’s recreate it!

GIF demo

Beginning the software

I’m going to jump into the p5 first, then we’ll sort out the hardware.

Starting point

Using the sample code provided, here we are:

let serial
let payload = 'waiting for data'
function setup() {
createCanvas(500, 300)
serial = new p5.SerialPort()
serial.open('/dev/tty.usbmodem142101')
serial.on('data', onData)
}
const onData = () => {
const currentString = trim(serial.readLine())
if (!currentString) return
payload = int(currentString)
}
function draw() {
background(255, 255, 255)
fill(0, 0, 0)
const data = int(map(payload, 0, 360, 0, height))
ellipse(100, data, 50, 50)
text(data, 10, 10)
}

Adding a background image

I turned to Unsplash, a stock photo website, & found this image of a MacBook. Here’s loading a background image into the canvas with p5:

let bg
function preload() {
bg = loadImage('https://images.unsplash.com/photo-1484788984921-03950022c9ef?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=2004&q=80')
}
function setup() {
createCanvas(796, 496)
// …
}
function draw() {
background(bg)
// …
}

Adding the screen

Next up, simulating the screen. It required a bit of trial-and-error, but here’s a rectangular screen on the laptop:

function draw() {
background(bg)
noStroke(0)
// const data = int(map(payload, 0, 360, 0, height))
fill(255)
// ellipse(100, data, 50, 50)
rect(275, 140, 282, 175, 2)
}

Hardware interlude

The breadboard

The only notable feature here is a light sensor, coupled with a resistor. Both are critical features.

Breadboard

Arduino program

The code for the Arduino is incredibly simple:

void setup() {
Serial.begin(9600);
}
void loop() {
int input = analogRead(A7);
Serial.println(input);
delay(10);
}

Connecting to the computer

Using the p5.serialcontrol app, I connected the Arduino to my MacBook over USB, & now data from the Arduino program is accessible at a local URL.

Magic, basically!

Back to the software

Where we left off:

let serial
let payload = 'waiting for data'
let bg
function preload() {
bg = loadImage(
'https://images.unsplash.com/photo-1484788984921-03950022c9ef?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=2004&q=80'
)
}
function setup() {
createCanvas(796, 496)
serial = new p5.SerialPort()
serial.open('/dev/tty.usbmodem142101')
serial.on('data', onData)
}
const onData = () => {
const currentString = trim(serial.readLine())
if (!currentString) return
payload = int(currentString)
}
function draw() {
background(bg)
noStroke(0)
const color = int(map(payload, 30, 180, 0, 255))
fill(color)
rect(275, 140, 282, 175, 2)
}

Fixing the flickering

With readouts 100 times per second, the screen was flickering wildly. I tried various debounce options & timeouts in JavaScript, but couldn’t get anything suitable.

I went with the simple fix: increasing the delay in the Arduino code, from 10 to 500 (half a second).

Without getting into animation, this is a little crude, but it’s better than the flickering.

Adding a brightness indicator

The screen’s a little empty still though. Let’s add a brightness indicator!

  1. Map the brightness level to a percentage
  2. Display the text
  3. Make the text look nice.

First up, adding the text:

function draw() {
// …
const brightness = int(map(payload, 30, 180, 0, 100))
fill(75)
text(`Brightness: ${brightness}%`, 290, 170)
}

But…could look better.

Dark mode!

Gotta hop on the trend :) A "dark mode" for the indicator:

fill(brightness < 50 ? 200 : 55)
textFont('system-ui, sans-serif')
textSize(18)
text()

Edge case

I adjusted my lamp & the brightness shot past 200%. Let’s prevent that from ever happening:

let brightness = int(map(payload, 30, 280, 0, 99))
fill(brightness < 50 ? 200 : 55)
if (brightness > 100) brightness = 100

Final project

Here’s the full code for the Arduino:

void setup() {
Serial.begin(9600);
}
void loop() {
int input = analogRead(A7);
Serial.println(input);
delay(500);
}

Finished p5 code:

let serial
let payload = 'waiting for data'
let bg
function preload() {
bg = loadImage(
'https://images.unsplash.com/photo-1484788984921-03950022c9ef?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=2004&q=80'
)
}
function setup() {
createCanvas(796, 496)
serial = new p5.SerialPort()
serial.open('/dev/tty.usbmodem142101')
serial.on('data', onData)
}
const onData = () => {
const currentString = trim(serial.readLine())
if (!currentString) return
payload = int(currentString)
}
function draw() {
background(bg)
noStroke(0)
const color = int(map(payload, 30, 280, 0, 255))
fill(color)
rect(275, 140, 282, 175, 2)
const brightness = int(map(payload, 30, 280, 0, 100))
fill(brightness < 50 ? 200 : 55)
textFont('system-ui, sans-serif')
textSize(18)
text(`Brightness: ${brightness}%`, 290, 170)
}

Demo

GIF demo

Final screenshots

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