Sam El-Husseini e3975e65e5 pxt-microbit Accessibility PR (#529 )

* Accessibility changes

2017-09-07 13:42:08 -07:00

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Pulse In

Returns the duration of a pulse (high or low) from a pin on the @boardname@ board in microseconds.

pins.pulseIn(DigitalPin.P0, PulseValue.High)

~avatar

Some pins are also used by the LED screen. Please read the page about pins carefully.

~

Parameters

name is a string that stores the name of the pin (P0, P1, or P2, up through P20)
value is the value of the pulse, high or low
maxDuration, maximum duration in micro-seconds. If no pulse is received

Returns

a number that represents the pulse duration in micro-seconds

Example: Measuring distance with a sonar

The following script sends a pulse on P0 and reads the pulse returned by a HC-SR04 sonar to determine the distance of the object in front of the sensor.

basic.forever(() => {
    // send pulse
    pins.digitalWritePin(DigitalPin.P0, 0)
    control.waitMicros(2)
    pins.digitalWritePin(DigitalPin.P0, 1)
    control.waitMicros(10)
    pins.digitalWritePin(DigitalPin.P0, 0)

    // read pulse
    led.plotBarGraph(pins.pulseIn(DigitalPin.P1, PulseValue.High) / 58, 0)
    basic.pause(100)
})

~hint

This function is not supported in the simulator.

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