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.
DFRobot · M5Stack links on this page are affiliate links: a purchase through them earns Velxio a small commission at no extra cost to you.
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 unlock the Linux and STM32 boards, WiFi and the offline desktop app. Maker and Pro add the AI agent; No AI leaves it out.
Discover the simulator + light AI help.
The full workbench, zero AI. You write every line.
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 Devkit C V4 circuit simulation you can run free in your browser on Velxio, by kiybiy36.
#include <LovyanGFX.hpp>
#include <DHT.h>
// ============================================================
// KONFIGURASI PIN
// ============================================================
#define DHTPIN 21
#define DHTTYPE DHT22
#define BUZZER_PIN 27
#define BUTTON_PIN 26
// ============================================================
// KONFIGURASI LEDC
// ============================================================
#define BUZZER_FREQ 2000
#define BUZZER_RESOLUTION 8
// ============================================================
// KONFIGURASI LOVYANGFX (ILI9341)
// ============================================================
class LGFX : public lgfx::LGFX_Device {
lgfx::Panel_ILI9341 _panel_instance;
lgfx::Bus_SPI _bus_instance;
public:
LGFX(void) {
{
auto cfg = _bus_instance.config();
cfg.spi_host = VSPI_HOST;
cfg.spi_mode = 0;
cfg.freq_write = 27000000;
cfg.freq_read = 16000000;
cfg.spi_3wire = false;
cfg.use_lock = true;
cfg.dma_channel = 1;
cfg.pin_sclk = 18;
cfg.pin_mosi = 23;
cfg.pin_miso = 19;
cfg.pin_dc = 2;
_bus_instance.config(cfg);
_panel_instance.setBus(&_bus_instance);
}
{
auto cfg = _panel_instance.config();
cfg.pin_cs = 15;
cfg.pin_rst = 4;
cfg.pin_busy = -1;
cfg.panel_width = 240;
cfg.panel_height = 320;
cfg.offset_x = 0;
cfg.offset_y = 0;
cfg.offset_rotation = 0;
cfg.readable = false;
cfg.invert = false;
cfg.rgb_order = false;
_panel_instance.config(cfg);
}
setPanel(&_panel_instance);
}
};
LGFX tft;
DHT dht(DHTPIN, DHTTYPE);
// ============================================================
// WARNA KUSTOM
// ============================================================
#define WARNA_UNGU_TUA 0x8010
#define WARNA_UNGU_MUDA 0xB81F
#define WARNA_MERAH 0xF800
#define WARNA_BIRU 0x001F
#define WARNA_KUNING 0xFFE0
#define WARNA_HIJAU 0x07E0
#define WARNA_PINK_HATI 0xF81F
// ============================================================
// NOT HAPPY BIRTHDAY
// ============================================================
int hbdMelodi[] = {
262, 262, 294, 262, 349, 330,
262, 262, 294, 262, 392, 349,
262, 262, 523, 440, 349, 330, 294,
466, 466, 440, 349, 392, 349
};
int hbdDurasi[] = {
4, 4, 4, 4, 4, 2,
4, 4, 4, 4, 4, 2,
4, 4, 4, 4, 4, 4, 2,
4, 4, 4, 4, 4, 2
};
int jumlahNot = 26;
// ============================================================
// VARIABEL GLOBAL
// ============================================================
float suhu = 0.0;
float kelembaban = 0.0;
unsigned long lastTime = 0;
unsigned long lastCountdown = 0;
const long interval = 4000;
int slideAktif = 1;
int hitunganMundur = 10;
int lastButtonState = HIGH;
int buttonState = HIGH;
unsigned long lastDebounceTime = 0;
const unsigned long debou