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.




35 boards across 6 CPU architectures — AVR8, ARM Cortex-M, ARM Cortex-A, RISC-V, Xtensa, and Linux. Including partner boards from Pimoroni, M5Stack, Seeed Studio and DFRobot. All running locally, no cloud needed.
One institution contract gives every student in the class a full Pro account. No per-seat checkout, no card details in a classroom.
Private projects, BOM and schematic exports, GitHub Sync and the offline desktop app, for everyone enrolled.
Billed once to your institution, per semester or per year. Volume pricing on request for large cohorts.
Arduino, ESP32, RP2040, STM32, ATtiny and Raspberry Pi, with SPICE analog solved alongside the firmware. Not a sandboxed mock.
The simulator stays free forever. Paid plans raise the daily AI quota and unlock the Linux boards, private projects and the offline desktop app.
Discover the simulator + light AI help.
For makers shipping real circuits with AI help.
Private projects, GitHub Sync and BOM exports.
Questions, bugs and ideas: the Discord and the issue tracker are open, and so is every line of the simulator.
An interactive ESP32-S3 circuit simulation you can run free in your browser on Velxio, by svitlana1981kusnirik.
/*
* ═══════════════════════════════════════════════════
* ESP32-S3: 24 світлодіоди (3 групи по 8) — ефект "дихання"
*
* Потенціометр 1 (GPIO 1) — яскравість
* Потенціометр 2 (GPIO 2) — швидкість дихання
*
* Група 1 → GPIO 4 (через транзистор T1)
* Група 2 → GPIO 5 (через транзистор T2)
* Група 3 → GPIO 6 (через транзистор T3)
*
* Транзистори: GPIO → [1 кОм] → база, емітер → GND,
* колектор → катоди групи, аноди LED → 3V3 через 220 Ом
* ═══════════════════════════════════════════════════
*/
const int GROUPS[3] = {4, 5, 6}; // піни груп (на бази транзисторів)
const int POT_BRIGHT = 1; // яскравість
const int POT_SPEED = 2; // швидкість дихання
const int PWM_FREQ = 5000; // 5 кГц — очі не бачать мерехтіння
const int PWM_RES = 12; // 12 біт = 4096 рівнів яскравості
unsigned long breathPhase = 0; // поточна фаза дихання
unsigned long lastTime = 0;
void setup() {
Serial.begin(115200);
// Налаштовуємо апаратний PWM (LEDC) для кожної групи
for (int i = 0; i < 3; i++) {
ledcAttach(GROUPS[i], PWM_FREQ, PWM_RES);
ledcWrite(GROUPS[i], 0); // старт з вимкнених LED
}
Serial.println("Дихання запущено! 🌬️");
}
void loop() {
unsigned long now = millis();
float dt = (now - lastTime) / 1000.0; // час минулого кадру в секундах
lastTime = now;
// ─── Читаємо потенціометри ───
// Яскравість: 0..4095 → згладжування країв
float brightRaw = analogRead(POT_BRIGHT) / 4095.0; // 0..1
float maxBright = brightRaw * brightRaw * 4095.0; // квадрат = плавніше на мінімумі
// Швидкість: тривалість одного циклу дихання 500..8000 мс
// Крутите Пот.2: вліво — повільне дихання, вправо — швидке
float cycleSec = map(analogRead(POT_SPEED), 0, 4095, 8000, 500) / 1000.0;
// ─── Фаза дихання ───
// Проходимо повний цикл (0..2π) за cycleSec секунд
breathPhase += (2.0 * PI / cycleSec) * dt;
if (breathPhase >= 2.0 * PI) breathPhase -= 2.0 * PI;
// ─── Форма "дихання" ───
// Синус + smoothstep = дуже плавне загоряння і потухання
float v = (sinf(breathPhase) + 1.0) / 2.0; // 0..1
v = v * v * (3.0 - 2.0 * v); // smoothstep
// ─<arg_value>── Записуємо яскравість у всі 3 групи ───
uint32_t level = (uint32_t)(v * maxBright);
for (int i = 0; i < 3; i++) {
ledcWrite(GROUPS[i], level);
}
delay(10); // ~100 кадрів/сек — плавне оновлення
}