Arduino, running the sketch you wrote
arduino-cli compiles it, an AVR8 core executes it instruction by instruction, and the LCD shows what the ATmega328P actually put on the bus. Uno, Nano, Mega and ATtiny85, no board on your desk.

Hardware is all about iteration. Velxio lets you wire a circuit, program the board and run it in seconds, real firmware on a real solver, right in the browser.
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Nothing on this page is a scripted animation: the firmware is compiled and executed, and the circuit around it is solved.
arduino-cli compiles it, an AVR8 core executes it instruction by instruction, and the LCD shows what the ATmega328P actually put on the bus. Uno, Nano, Mega and ATtiny85, no board on your desk.

arduino-cli or ESP-IDF compiles the sketch, then AVR8, RP2040, RISC-V, Xtensa or ARM executes it instruction by instruction. What the OLED draws and what the serial monitor prints is what the chip actually did.

ngspice compiled to WebAssembly runs a full nodal analysis about 60 times a second. GPIO pins drive real nets, ADC inputs read solved node voltages, and probes report RMS, DC and current wherever you drop them.

Adders, comparators, decoders, flip-flops and a 1-bit ALU slice: no microcontroller anywhere, just gates, switches and LEDs solved as a real net. The classroom half of electronics, without the breadboard.

The M5Stack Cardputer with its keyboard, Seeed's round display keeping time, Pimoroni's Badger 2350 driving e-paper, and DFRobot's UNIHIKER M10 in the catalogue alongside them. Their makers sent the hardware so the emulation could be checked against the real thing.




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Private projects, BOM and schematic exports, GitHub Sync and the offline desktop app, for everyone enrolled.
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Arduino, ESP32, RP2040, STM32, ATtiny and Raspberry Pi, with SPICE analog solved alongside the firmware. Not a sandboxed mock.
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Questions, bugs and ideas: the Discord and the issue tracker are open, and so is every line of the simulator.
KKAR
An interactive Arduino Uno circuit simulation you can run free in your browser on Velxio, by zahracallista2510.
#include <Wire.h> // Menyertakan pustaka untuk komunikasi I2C
#include <LiquidCrystal_I2C.h> // Menyertakan pustaka untuk mengontrol layar LCD I2C
const int trigPin = 9;// Menentukan pin Trig sensor ultrasonik di pin 9
const int echoPin = 10; // Menentukan pin Echo sensor ultrasonik di pin 10
const int ledBiru = 7; // Menentukan pin LED Biru di pin 7
const int ledMerah = 8; // Menentukan pin LED Putih di pin 8
const int buzzerPin = 4; // Menentukan pin Buzzer di pin 4
long duration;// Variabel untuk menyimpan durasi waktu pantulan gelombang
float distance;//Variabel untuk menyimpan hasil perhitungan jarak dalam cm
LiquidCrystal_I2C lcd(0x27, 16, 2);// Mengatur alamat I2C LCD (0x27) dengan ukuran 16x2
void setup() { // Fungsi yang dijalankan sekali saat awal program aktif
Serial.begin(115200);// Mengaktifkan komunikasi Serial dengan kecepatan 115200
pinMode(trigPin, OUTPUT);// Mengatur pin Trig sebagai output (pengirim sinyal)
pinMode(echoPin, INPUT); // Mengatur pin Echo sebagai input (penerima sinyal)
pinMode(ledBiru, OUTPUT);// Mengatur pin LED Biru sebagai output
pinMode(ledMerah, OUTPUT); // Mengatur pin LED Putih sebagai output
pinMode(buzzerPin, OUTPUT); // Mengatur pin Buzzer sebagai output
lcd.init();// Menginisialisasi layar LCD
lcd.backlight(); // Menyalakan lampu latar LCD
lcd.setCursor(0, 0); // Mengatur posisi kursor LCD ke kolom 0, baris 0
lcd.print("Nungguin Yaaaaa");// Menampilkan teks sapaan di layar LCD
delay(1000); // Memberikan jeda waktu 1 detik
lcd.clear(); // Menghapus tampilan teks pada layar LCD
} // Penutup fungsi setup
void loop() { // Fungsi utama yang berjalan berulang-ulang secara terus-menerus
// Mengirim pulsa ultrasonik
digitalWrite(trigPin, LOW); // Memastikan pin Trig dalam kondisi LOW
delayMicroseconds(2); // Menunggu selama 2 mikrodetik
digitalWrite(trigPin, HIGH);// Mengirim gelombang dengan membuat pin Trig menjadi HIGH
delayMicroseconds(10);// Menjaga pin Trig tetap HIGH selama 10 mikrodetik
digitalWrite(trigPin, LOW); // Mematikan kembali pin Trig menjadi LOW
// Membaca pantulan
duration = pulseInLong(echoPin, HIGH,30000);// Menghitung waktu lamanya gelombang pantul kembali ke pin Echo
// Menghitung jarak dalam cm
distance = duration * 0.0343 / 2.0;// Mengubah waktu (durasi) menjadi satuan jarak sentimeter (cm)
// Serial Monitor
Serial.print("Jarak: ");// Mencetak teks "Jarak: " ke Serial Monitor komputer
Serial.print(distance, 2);// Mencetak angka jarak dengan 2 desimal di belakang koma
Serial.println(" cm");// Mencetak satuan " cm" dan membuat baris baru
// LCD
lcd.setCursor(0, 0);// Mengatur kursor LCD ke baris pertama
lcd.print("Jarak: "); // Menampilkan label "Jarak: " serta spasi pembersih
lcd.setCursor(0, 1);
lcd.print(distance, 2);
lcd.print(" cm ");
// Jika jarak kurang dari 80 cm
if (distance < 80.00) {
digitalWrite(ledBiru, HIGH);
digitalWrite(ledMerah, LOW);
tone(buzzerPin,