Edrys AVR8js Module

An AVR8js-based Arduino simulator for edrys-Lite. It emulates an ATmega328P (Arduino Uno) in the browser using avr8js, with interactive Wokwi circuit components and no hardware required.

Import the module via:

https://edrys-labs.github.io/module-avr8js/index.html

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Configuration

The module accepts two configuration properties:

Property	Type	Description	Default
modules	String	HTML string of Wokwi circuit elements to display	""
execute	String	Edrys message topic the module listens on for code/hex	"execute"

YAML example:

modules: |
  <wokwi-led color='red'   pin='13' label='13'></wokwi-led>
  <wokwi-led color='green' pin='12' label='12'></wokwi-led>
  <wokwi-led color='blue'  pin='11' label='11'></wokwi-led>
  <span id='simulation-time'></span>

execute: execute

JSON example:

{
  "modules": "<wokwi-led color='red' pin='13' label='13'></wokwi-led>\n<wokwi-led color='green' pin='12' label='12'></wokwi-led>\n<span id='simulation-time'></span>",
  "execute": "execute"
}

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Available Circuit Elements

All elements are standard Wokwi web components placed in the modules HTML string.

Utility

Element	Description
<span id='simulation-time'></span>	Displays elapsed simulation time and CPU performance (e.g. Simulation time: 00:05.123 (98%))

Digital Output

wokwi-led — LED

<wokwi-led color='red' pin='13' label='LED'></wokwi-led>

Attribute	Description
color	Any CSS color or name: red, green, blue, yellow, orange, etc.
pin	Arduino digital pin number (0–13)
label	Optional text label displayed on the component

Digital Input

wokwi-pushbutton — Push Button

<wokwi-pushbutton pin='2'></wokwi-pushbutton>

Attribute	Description
pin	Arduino digital pin to drive HIGH when pressed

Analog Input

wokwi-potentiometer — Potentiometer

<wokwi-potentiometer pin='A0'></wokwi-potentiometer>

Attribute	Description
pin	Analog pin (A0–A5) — returns ADC values 0–1023

wokwi-ntc-temperature-sensor — NTC Temperature Sensor

<wokwi-ntc-temperature-sensor pin='A2'></wokwi-ntc-temperature-sensor>

Attribute	Description
pin	Analog pin (A0–A5)

Interactive slider lets you set temperature from −40 °C to +125 °C. The module simulates the corresponding NTC thermistor resistance and updates the ADC value accordingly.

Displays

wokwi-lcd1602 — 16×2 Character LCD (I2C)

<wokwi-lcd1602></wokwi-lcd1602>

I2C address: 0x27. Use the LiquidCrystal_I2C library in your sketch.

wokwi-ssd1306 — 128×64 OLED Display (I2C)

<wokwi-ssd1306></wokwi-ssd1306>

I2C address: 0x3D. Use the Adafruit_SSD1306 library in your sketch.

PWM / Actuators

wokwi-servo — Servo Motor

<wokwi-servo pin='9'></wokwi-servo>

Attribute	Description
pin	PWM-capable pin. Pulse width 1000–2000 µs maps to 0–180°. Default: 90°.

Use the Servo library in your sketch.

wokwi-buzzer — Buzzer

<wokwi-buzzer pin='8' frequency='1000'></wokwi-buzzer>

Attribute	Description
pin	Digital pin driven HIGH to activate audio
frequency	Tone frequency in Hz (default: 1000)

Audio is generated via the Web Audio API. A user interaction (click) is required to unlock audio in the browser.

Addressable LEDs

wokwi-neopixel-matrix — NeoPixel RGB Matrix

<wokwi-neopixel-matrix cols='8' rows='8' pin='5'></wokwi-neopixel-matrix>

Attribute	Description
pin	Data pin (WS2812B protocol)
cols	Number of columns
rows	Number of rows

Use the Adafruit_NeoPixel library in your sketch.

Real-Time Clock

wokwi-ds1307 — DS1307 RTC (I2C)

<wokwi-ds1307></wokwi-ds1307>

I2C address: 0x68. Initializes to the current system time. Use the DS1307RTC library in your sketch.

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Pin Mapping

Arduino Pin	AVR Port
D0–D7	PORTD (PD0–PD7)
D8–D13	PORTB (PB0–PB5)
A0–A5	PORTC (PC0–PC5)

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Example Configurations

Blink (single LED)

modules: |
  <wokwi-led color='red' pin='13' label='LED'></wokwi-led>
  <span id='simulation-time'></span>

Button + LED

modules: |
  <wokwi-pushbutton pin='2'></wokwi-pushbutton>
  <wokwi-led color='green' pin='13'></wokwi-led>
  <span id='simulation-time'></span>

Potentiometer + LCD

modules: |
  <wokwi-potentiometer pin='A0'></wokwi-potentiometer>
  <wokwi-lcd1602></wokwi-lcd1602>
  <span id='simulation-time'></span>

Arduino sketch (requires LiquidCrystal_I2C):

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() { lcd.init(); lcd.backlight(); }

void loop() {
  lcd.setCursor(0, 0);
  lcd.print("ADC: ");
  lcd.print(analogRead(A0));
  delay(100);
}

OLED Display

modules: |
  <wokwi-ssd1306></wokwi-ssd1306>
  <span id='simulation-time'></span>

Arduino sketch (requires Adafruit_SSD1306):

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

Adafruit_SSD1306 display(128, 64, &Wire, -1);

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, 0x3D);
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("Hello!");
  display.display();
}
void loop() {}

Servo Motor

modules: |
  <wokwi-servo pin='9'></wokwi-servo>
  <span id='simulation-time'></span>

Arduino sketch:

#include <Servo.h>
Servo s;
void setup() { s.attach(9); }
void loop() {
  for (int a = 0; a <= 180; a++) { s.write(a); delay(15); }
  for (int a = 180; a >= 0; a--) { s.write(a); delay(15); }
}

NeoPixel Matrix

modules: |
  <wokwi-neopixel-matrix cols='8' rows='8' pin='5'></wokwi-neopixel-matrix>
  <span id='simulation-time'></span>

Arduino sketch (requires Adafruit_NeoPixel):

#include <Adafruit_NeoPixel.h>
Adafruit_NeoPixel pixels(64, 5, NEO_GRB + NEO_KHZ800);
void setup() { pixels.begin(); }
void loop() {
  pixels.fill(pixels.Color(255, 0, 0));
  pixels.show();
  delay(500);
  pixels.clear();
  pixels.show();
  delay(500);
}

Temperature Sensor

modules: |
  <wokwi-ntc-temperature-sensor pin='A2'></wokwi-ntc-temperature-sensor>
  <span id='simulation-time'></span>

Buzzer

modules: |
  <wokwi-buzzer pin='8' frequency='440'></wokwi-buzzer>
  <wokwi-pushbutton pin='2'></wokwi-pushbutton>
  <span id='simulation-time'></span>

Arduino sketch:

void setup() { pinMode(8, OUTPUT); pinMode(2, INPUT); }
void loop() {
  if (digitalRead(2) == HIGH) tone(8, 440);
  else noTone(8);
}

Real-Time Clock + LCD

modules: |
  <wokwi-ds1307></wokwi-ds1307>
  <wokwi-lcd1602></wokwi-lcd1602>
  <span id='simulation-time'></span>

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How It Works

1. An external editor module compiles Arduino code and publishes the hex on the execute topic (configurable).
2. This module receives the hex, loads it into the AVR8js emulator, and starts a 16 MHz simulation loop.
3. Wokwi components react to AVR pin state changes in real time (GPIO, PWM, I2C, SPI).
4. Serial output (Serial.print) is displayed in the built-in terminal.
5. Interactive components (button, potentiometer, temperature slider) inject input back into the simulation.