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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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An interactive Aitewinrobot Esp32C3 Supermini circuit simulation you can run free in your browser on Velxio, by george.
#include <Arduino.h>
const uint8_t A1_PIN = 0;
const uint8_t A2_PIN = 1;
const uint8_t B1_PIN = 6;
const uint8_t B2_PIN = 7;
const uint8_t LED1_PIN = 8;
const uint8_t LED2_PIN = 5;
// Niet-actieve A-lijnen hoogohmig met pull-up
void releaseA() {
pinMode(A1_PIN, INPUT_PULLUP);
pinMode(A2_PIN, INPUT_PULLUP);
}
// Meet een ingang meerdere keren.
// Alleen als vrijwel alle samples LOW zijn,
// beschouwen we hem als LOW.
bool stableLow(uint8_t pin) {
int lowCount = 0;
for (int i = 0; i < 20; i++) {
if (digitalRead(pin) == LOW) {
lowCount++;
}
delay(2);
}
return lowCount >= 18;
}
void setup() {
releaseA();
pinMode(B1_PIN, INPUT_PULLUP);
pinMode(B2_PIN, INPUT_PULLUP);
pinMode(LED1_PIN, OUTPUT);
pinMode(LED2_PIN, OUTPUT);
digitalWrite(LED1_PIN, LOW);
digitalWrite(LED2_PIN, LOW);
}
void loop() {
// ---------------------------------
// Eerst A1 activeren
// ---------------------------------
releaseA();
delay(10);
pinMode(A1_PIN, OUTPUT);
digitalWrite(A1_PIN, LOW);
delay(50);
bool A1naarB1 = stableLow(B1_PIN);
bool A1naarB2 = stableLow(B2_PIN);
// ---------------------------------
// Daarna A2 activeren
// ---------------------------------
releaseA();
delay(10);
pinMode(A2_PIN, OUTPUT);
digitalWrite(A2_PIN, LOW);
delay(50);
bool A2naarB1 = stableLow(B1_PIN);
bool A2naarB2 = stableLow(B2_PIN);
releaseA();
// ---------------------------------
// Beoordeling
// ---------------------------------
// Ader 1 is goed als:
// A1 uitsluitend op B1 uitkomt.
bool ok1 =
A1naarB1 &&
!A1naarB2 &&
!A2naarB1;
// Ader 2 is goed als:
// A2 uitsluitend op B2 uitkomt.
bool ok2 =
A2naarB2 &&
!A2naarB1 &&
!A1naarB2;
// Beide LEDs zijn gewone externe LEDs:
// HIGH = aan
digitalWrite(LED1_PIN, ok1 ? HIGH : LOW);
digitalWrite(LED2_PIN, ok2 ? HIGH : LOW);
delay(200);
}