Value Units

Plaquette’s value-units Float, Integer, and Boolean wrap basic types (float, int or bool), allowing to use them transparently as units in a Plaquette flow. These units can be used like a normal variables but also send to and receive from other units using the flow operator (>>). You can think of value-units as variables that can participate in data flows.

The flow operator >> connects is not compatible with primitive types such as float, int, and bool.

Value units address this problem by turning primitive variables into Plaquette units.

This code shows valid and invalid uses of the flow operator:

#include <Plaquette.h>

Wave wave(1.0f); // wave oscillator
DigitalOut led(LED_BUILTIN); // output LED
float x = 0.0f;  // primitive type variable (float)

void step() {
  wave >> led; // ✓ valid : unit  >> unit
  x    >> led; // ✓ valid : float >> unit
  wave >> x;   // × error : unit  >> float
}

Example

This example combines two oscillators, stores the result in a Float unit, and reuses it two control two LEDs.

#include <Plaquette.h>

// Create two wave oscillators.
Wave waveA(SINE, 1.0f);
Wave waveB(SINE, 1.2f);

// Create two LED outputs.
AnalogOut led1(9);
AnalogOut led2(11);

// Create a Float to store the combined signal.
Float mix;

void step() {
  // Sum the two waves and store the result.
  (waveA + waveB) >> mix;
  // Compute average.
  mix /= 2;
  // Reuse the same value in multiple places.
  mix >> led1;
  // Use math to invert the signal.
  (1-mix) >> led2;
}

Example

This example uses the Boolean unit type to combine two button states into a single logical condition. It activates an LED only when both buttons are pressed and plots the states.

#include <Plaquette.h>

// Create two button inputs.
DigitalIn buttonA(BUTTON_A_PIN);
DigitalIn buttonB(BUTTON_B_PIN);

// Create LED output.
DigitalOut led(LED_BUILTIN);

// Create monitor.
Plotter plotter(115200, "pressA,pressB,pressBoth"); // plotter with baud rate and labels

// Create a Boolean to store the combined condition.
Boolean bothPressed = false;

void step() {
  // Combine the two button states.
  (buttonA && buttonB) >> bothPressed;
  // Send to LED.
  bothPressed >> led;
  // Plot states.
  buttonA >> plotter;
  buttonB >> plotter;
  bothPressed >> plotter;
}

See Also

• >> (flow)