55 lines
1.4 KiB
Markdown
55 lines
1.4 KiB
Markdown
# Pulse In
|
|
|
|
Returns the duration of a pulse (high or low) from a [pin](/device/pins) on
|
|
the @boardname@ board in microseconds.
|
|
|
|
```sig
|
|
pins.pulseIn(DigitalPin.P0, PulseValue.High)
|
|
```
|
|
|
|
## ~avatar
|
|
|
|
Some pins are also used by the [LED screen](/device/screen).
|
|
Please read the [page about pins](/device/pins) carefully.
|
|
|
|
## ~
|
|
|
|
## Parameters
|
|
|
|
* ``name`` is a [string](/types/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](/types/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.
|
|
|
|
```blocks
|
|
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.
|
|
|
|
### ~
|
|
|
|
## See also
|
|
|
|
[digital write pin](/reference/pins/digital-write-pin),
|