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.
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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-C3 circuit simulation you can run free in your browser on Velxio, by rtrahishop.
#include <Arduino.h>
#include <Wire.h>
#include <WiFi.h>
#include <WebServer.h>
#include <Preferences.h>
#include <U8g2lib.h>
#include <time.h>
// =====================================================
// ORBI by HR Innovexa
// ESP32-C3 + SH1107 128x128 OLED
// =====================================================
// ---------- PIN CONFIGURATION ----------
const int POWER_PIN = 3;
const int UP_PIN = 4;
const int DOWN_PIN = 5;
const int SET_PIN = 6;
const int TOUCH_PIN = 7;
const int BUZZER_PIN = 2;
const int SDA_PIN = 8;
const int SCL_PIN = 9;
// Keep these values calibrated for your OLED
const int X_OFFSET = -20;
const int SAFE_W = 120;
const bool TOUCH_ACTIVE_HIGH = true;
const unsigned long DEBOUNCE_MS = 50;
const unsigned long DOUBLE_TAP_MS = 450;
const unsigned long LONG_PRESS_MS = 1000;
// ---------- DISPLAY ----------
U8G2_SH1107_128X128_F_HW_I2C oled(
U8G2_R2,
U8X8_PIN_NONE
);
WebServer server(80);
Preferences prefs;
// ---------- WIFI ----------
String wifiSSID = "";
String wifiPASS = "";
bool wifiConnected = false;
bool setupAP = false;
// ---------- DEVICE STATE ----------
bool deviceEnabled = true;
enum ScreenMode {
SCREEN_HOME,
SCREEN_TIMER,
SCREEN_WATER,
SCREEN_ROUTINE,
SCREEN_MESSAGE
};
ScreenMode screenMode = SCREEN_HOME;
String messageText = "";
String routineText = "";
unsigned long screenStartedMs = 0;
unsigned long messageDurationMs = 6500;
unsigned long lastDisplayMs = 0;
// ---------- FOCUS TIMER ----------
bool timerRunning = false;
bool timerPaused = false;
unsigned long focusTimerStartMs = 0;
unsigned long focusTimerDurationMs = 0;
unsigned long focusTimerRemainingMs = 0;
unsigned long focusSessionCount = 0;
unsigned long focusMinutesTotal = 0;
// ---------- TOUCH ----------
bool touchWasPressed = false;
bool longPressHandled = false;
unsigned long touchStartMs = 0;
unsigned long lastTapMs = 0;
int touchTapCount = 0;
// ---------- POWER BUTTON ----------
int lastPowerReading = HIGH;
int stablePowerState = HIGH;
unsigned long lastPowerChangeMs = 0;
// ---------- REMINDERS ----------
unsigned long lastWaterReminderMs = 0;
unsigned long lastAutoMessageMs = 0;
const unsigned long WATER_INTERVAL_MS =
2UL * 60UL * 60UL * 1000UL;
const unsigned long MESSAGE_INTERVAL_MS =
90UL * 60UL * 1000UL;
// ---------- CONTENT ----------
const char* MESSAGES[] = {
"Amake ki bhule geso?",
"Kajer mood koi? Cholo focus kori!",
"Error 404: Focus khuje pawa jacche na!",
"Darun! Ajke bhalo focus korteso!",
"Tumi ar ORBI ekhon powerful team!",
"Brain: kaj kori. Ami: aro 5 min scroll!",
"Facebook scroll komao, kajta shesh koro!",
"Ami lazy na, energy save kortesi!",
"Bhai, ektu cha-nasta kheye nao!",
"Exam shamne! Phone rekhe pora shuru koro!",
"Choto choto focus session-e boro result ashe!",
"Break nao, tarpor abar focus!"
};
const int MESSAGE_COUNT =
sizeof(MESSAGES) / sizeof(MESSAGES[0]);
const char* HEALTH_MESSAGES[] = {
"Onekkhon pani khao ni! Ekhon ek glass pani kheye nao.",