pxt-calliope/docs/reference/pins/pulse-in.md

pulse In

Get the duration, in microseconds, of a pulse (high or low) from one of the pins.

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

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

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Simulator: This function needs real hardware to work with. It's not supported in the simulator.

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Parameters

• name the name of the pin (P0, P1, or P2, up through P20).
• value the value of the pulse, either high or low.
• maxDuration, maximum duration to wait for the pulse in microseconds. If no pulse is received, the duration returned is 0.

Returns

• a number that is the pulse duration in microseconds.

Example: Measuring distance with a sonar

Send a pulse on P0 and read a pulse returned by a HC-SR04 sonar ultrasonic sensor. The sensor determines the distance of the object in front of it.

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)
})

See also

digital write pin