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.
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Private projects, BOM and schematic exports and GitHub Sync, 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, WiFi with internet included. Paid plans unlock the Linux and STM32 boards, custom WiFi networks and the local network gateway. 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.
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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 circuit simulation you can run free in your browser on Velxio, by felipe021-com.
#include <TinyGPSPlus.h>
#include <SPI.h>
#include <SD.h>
#include <Wire.h>
#include <WiFi.h>
#include <WebServer.h>
#include <vector>
#include <algorithm>
// ---------------- MODO WIFI (baixar os arquivos do SD sem tirar o cartao) ----------------
// Como usar: com a gravacao PARADA, SEGURE o botao por 3 segundos.
// 1) O LED2 passa a piscar rapido: o ConecTrack criou uma rede WiFi.
// 2) No celular/notebook, conecte na rede abaixo.
// 3) Abra http://192.168.4.1 no navegador: lista de arquivos com Baixar / Apagar.
// 4) Pra sair: segure o botao 3 s de novo, ou aperte rapido pra comecar a gravar.
// Obs.: com o WiFi ligado a amostragem fica pausada (e os pinos GPIO25/26 nao leem no WiFi).
#define WIFI_SSID "ConecTrack"
#define WIFI_SENHA "conectrack1" // minimo 8 caracteres. Troque se quiser.
const unsigned long TEMPO_PRESSAO_LONGA = 3000; // ms
WebServer server(80);
bool wifiOn = false;
void wifiParar(); // declarada aqui porque iniciarGravacao() usa
// ---------------- MPU6050 / clones (leitura direta dos registradores) ----------------
// Nao usa a biblioteca Adafruit: ela recusa clones (WHO_AM_I diferente de 0x68).
// O seu modulo responde WHO_AM_I = 0x70 (chip MPU-6500), que usa os mesmos registradores
// de acelerometro e giroscopio e funciona normalmente aqui.
uint8_t mpuEndereco = 0x68;
uint8_t mpuQuem = 0;
bool mpuOk = false;
const float ACC_LSB_POR_G = 4096.0f; // faixa +-8 g
const float GYRO_LSB_POR_DPS = 65.5f; // faixa +-500 graus/s
// Aceleracao em g, giroscopio em graus/s, temperatura do sensor em graus C
float ACCX = 0, ACCY = 0, ACCZ = 0;
float GYROX = 0, GYROY = 0, GYROZ = 0;
float TEMPM = 0;
bool mpuEscrever(uint8_t reg, uint8_t valor) {
Wire.beginTransmission(mpuEndereco);
Wire.write(reg);
Wire.write(valor);
return Wire.endTransmission() == 0;
}
bool mpuLerRegs(uint8_t reg, uint8_t* buf, uint8_t n) {
Wire.beginTransmission(mpuEndereco);
Wire.write(reg);
if (Wire.endTransmission(false) != 0) return false;
if (Wire.requestFrom((int)mpuEndereco, (int)n) != n) return false;
for (uint8_t i = 0; i < n; i++) buf[i] = Wire.read();
return true;
}
bool mpuIniciar() {
// procura em 0x68 e depois 0x69
bool achou = false;
for (uint8_t end = 0x68; end <= 0x69; end++) {
Wire.beginTransmission(end);
if (Wire.endTransmission() == 0) { mpuEndereco = end; achou = true; break; }
}
if (!achou) return false;
if (!mpuLerRegs(0x75, &mpuQuem, 1)) return false; // WHO_AM_I
if (!mpuEscrever(0x6B, 0x01)) return false; // acorda, clock do giroscopio
delay(100);
mpuEscrever(0x19, 9); // taxa de amostragem interna: 100 Hz
mpuEscrever(0x1A, 0x04); // filtro digital ~21 Hz
mpuEscrever(0x1B, 0x08); // giroscopio +-500 graus/s
mpuEscrever(0x1C, 0x10); // acelerometro +-8 g
mpuEscrever(0x1D, 0x04); // filtro do acelerometro (so existe no 6500; no 6050 e ignorado)
delay(50);
return true;
}
// ---------------- GPS ----------------
// O baud tem q