range

Overview

The range node maps numeric values from one range to another. It supports three actions: scale (linear interpolation), clamp (limit to bounds), and wrap (modulo wrap-around). Essential for converting raw ADC readings to engineering units, mapping sensor inputs to PWM outputs, or normalizing data for dashboards.

Properties

Range Actions

// Formula:
// out = (val - minIn) / (maxIn - minIn)
//       * (maxOut - minOut) + minOut

// Example: 0-1023 → 0-3.3V
// Input:  512
// Output: 1.65

// Scales then clamps:
// minOut=0, maxOut=100

// Input:  150 → Output: 100
// Input:  -20 → Output: 0
// Input:   50 → Output: 50
// Values never exceed bounds

// Wraps around using modulo:
// minOut=0, maxOut=360

// Input: 370 → Output: 10
// Input: 720 → Output: 0
// Input: -10 → Output: 350
// Useful for angles/rotations

Example: Sensor ADC to Voltage Conversion

Convert a 10-bit ADC reading (0-1023) to an analog voltage (0-3.3V).

// Range node configuration
{
  "action": "scale",
  "minIn": 0,
  "maxIn": 1023,
  "minOut": 0,
  "maxOut": 3.3,
  "round": false
}

// Input message
{
  "topic": "adc/channel0",
  "payload": 512
}

// Output message
{
  "topic": "adc/channel0",
  "payload": 1.6504
}

// Another example:
// Input: 1023 → Output: 3.3
// Input: 0    → Output: 0
// Input: 768  → Output: 2.475

Example: PWM Duty Cycle Mapping

Map a 0-100% brightness percentage to a PWM duty cycle value (0-255) for LED control.

// Range node configuration
{
  "action": "clamp",
  "minIn": 0,
  "maxIn": 100,
  "minOut": 0,
  "maxOut": 255,
  "round": true
}

// Input: brightness slider at 75%
{
  "payload": 75
}

// Output: PWM value (clamped and rounded)
{
  "payload": 191
}

// Clamp prevents over-drive:
// Input: 120 → Output: 255 (clamped to max)
// Input: -10 → Output: 0   (clamped to min)

Example: Joystick to Servo Angle

Map an analog joystick input (-512 to 512) to a servo angle (0-180 degrees).

// Range node configuration
{
  "action": "scale",
  "minIn": -512,
  "maxIn": 512,
  "minOut": 0,
  "maxOut": 180,
  "round": true
}

// Joystick centered (0)
{ "payload": 0 }   // → { "payload": 90 }

// Joystick full left (-512)
{ "payload": -512 } // → { "payload": 0 }

// Joystick full right (512)
{ "payload": 512 }  // → { "payload": 180 }

Common Use Cases