Hardware GPIO & Analog I/OCopy Anchor Link

The System.gpio (or global GPIO) object provides direct hardware control over the microcontroller's general-purpose input/output pins and analog converters.

Board pinouts and schematics can be found in the KryonOS GitHub Repository.

ConstantsCopy Anchor Link

Digital I/O FunctionsCopy Anchor Link

System.gpio.pinMode(pin, mode)Copy Anchor Link

Configures the physical operating mode of a GPIO pin.

• Parameters:
  • pin (Integer): Microcontroller GPIO number.
  • mode (Integer): INPUT, OUTPUT, or INPUT_PULLUP.
• Returns: undefined

System.gpio.digitalWrite(pin, state)Copy Anchor Link

Sets the voltage output state of a configured output pin.

• Parameters:
  • pin (Integer)
  • state (Integer): HIGH (3.3V) or LOW (0V).
• Returns: undefined

System.gpio.digitalRead(pin)Copy Anchor Link

Reads the digital logic state of a pin.

• Parameters: pin (Integer)
• Returns: Integer (1 for HIGH, 0 for LOW).

Analog & Pulse MeasurementCopy Anchor Link

System.gpio.analogRead(pin)Copy Anchor Link

Reads the voltage on an ADC-capable pin using the ESP32's 12-bit Successive Approximation Register (SAR) ADC.

• Parameters: pin (Integer): ADC1 or ADC2 pin number (e.g. GPIO 32, 33, 34, 35, 36, 39).
• Returns: Integer (0 to 4095, corresponding to 0V to 3.3V).

System.gpio.analogWrite(pin, duty)Copy Anchor Link

Initiates software pulse-width modulation on a digital pin.

• Parameters:
  • pin (Integer)
  • duty (Integer, 0 to 255)
• Returns: undefined

System.gpio.pulseIn(pin, state, timeout)Copy Anchor Link

Measures the duration of an incoming pulse with microsecond precision. The JavaScript thread is suspended while native C++ hardware timers measure the pulse width.

• Parameters:
  • pin (Integer): GPIO pin connected to signal.
  • state (Integer): HIGH or LOW to measure.
  • timeout (Integer, optional): Timeout in microseconds (default 1000000).
• Returns: Integer: Duration in microseconds (or 0 if timed out).

Code Example: HC-SR04 Ultrasonic Distance SensorCopy Anchor Link

var TRIG_PIN = 12;
var ECHO_PIN = 13;

System.gpio.pinMode(TRIG_PIN, System.gpio.OUTPUT);
System.gpio.pinMode(ECHO_PIN, System.gpio.INPUT);

function readDistanceCm() {
  // Send 10us trigger pulse
  System.gpio.digitalWrite(TRIG_PIN, System.gpio.LOW);
  System.delayMicroseconds(2);
  System.gpio.digitalWrite(TRIG_PIN, System.gpio.HIGH);
  System.delayMicroseconds(10);
  System.gpio.digitalWrite(TRIG_PIN, System.gpio.LOW);
  
  // Measure return echo pulse in microseconds
  var durationUs = System.gpio.pulseIn(ECHO_PIN, System.gpio.HIGH, 30000);
  
  if (durationUs === 0) {
    return -1; // Out of range or timeout
  }
  
  // Sound travels at ~0.0343 cm/us (divide by 2 for round-trip)
  var distanceCm = (durationUs * 0.0343) / 2;
  return distanceCm;
}

// Polling loop
var distance = readDistanceCm();
System.print("Measured Distance: " + distance.toFixed(2) + " cm");