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r-pi-usonic

r-pi-usonic

A high performance, memory mapped, Node.js API for the HC-SR04 ultrasonic sensor connected to a Raspberry Pi.

license npm downloads

build coverage code climate dependencies devDependencies

Getting Started

Installation

npm install r-pi-usonic --save

Integration

var usonic = require('r-pi-usonic');

API

usonic.init(callback)

Creates the memory mapping with a device-specific memory offset.

You must call this function only once and before any other function.

usonic.init(function (error) {
    if (error) {
        ...
    } else {
        ...
    }
});

usonic.createSensor(echoPin, triggerPin, [timeout])

Creates a new ultrasonic sensor function and returns it. The measurement timeout has a default value of 750 µs.

var sensor = usonic.createSensor(24, 23, 450);

sensor()

Returns the distance in cm if no measurement timeout occurs, and -1 otherwise.

var distance = sensor();

Example

This example needs access to the physical memory, so it must run as root.

sudo node examples/surveyor.js

Example: hcsr04.png

Raspberry Pi GPIO Pin Layout

Raspberry Pi Model A/B (Rev 1.0)

Assignment Pin Pin Assignment
3.3V 1 2 5V
GPIO 0 (SDA0) 3 4 5V
GPIO 1 (SCL0) 5 6 GROUND
GPIO 4 7 8 GPIO 14 (TXD0)
GROUND 9 10 GPIO 15 (RXD0)
GPIO 17 11 12 GPIO 18
GPIO 21 13 14 GROUND
GPIO 22 15 16 GPIO 23
3.3V 17 18 GPIO 24
GPIO 10 (SPI_MOSI) 19 20 GROUND
GPIO 9 (SPI_MISO) 21 22 GPIO 25
GPIO 11 (SPI_SCLK) 23 24 GPIO 8 (SPI_CE0_N)
GROUND 25 26 GPIO 7 (SPI_CE1_N)

Raspberry Pi Model A/B (Rev 2.0)

Assignment Pin Pin Assignment
3.3V 1 2 5V
GPIO 2 (SDA1) 3 4 5V
GPIO 3 (SCL1) 5 6 GROUND
GPIO 4 7 8 GPIO 14 (TXD0)
GROUND 9 10 GPIO 15 (RXD0)
GPIO 17 11 12 GPIO 18
GPIO 27 13 14 GROUND
GPIO 22 15 16 GPIO 23
3.3V 17 18 GPIO 24
GPIO 10 (SPI_MOSI) 19 20 GROUND
GPIO 9 (SPI_MISO) 21 22 GPIO 25
GPIO 11 (SPI_SCLK) 23 24 GPIO 8 (SPI_CE0_N)
GROUND 25 26 GPIO 7 (SPI_CE1_N)

Raspberry Pi Model B+ / Raspberry Pi 2 Model B

Assignment Pin Pin Assignment
3.3V 1 2 5V
GPIO 2 (SDA1) 3 4 5V
GPIO 3 (SCL1) 5 6 GROUND
GPIO 4 7 8 GPIO 14 (TXD0)
GROUND 9 10 GPIO 15 (RXD0)
GPIO 17 11 12 GPIO 18
GPIO 27 13 14 GROUND
GPIO 22 15 16 GPIO 23
3.3V 17 18 GPIO 24
GPIO 10 (SPI_MOSI) 19 20 GROUND
GPIO 9 (SPI_MISO) 21 22 GPIO 25
GPIO 11 (SPI_SCLK) 23 24 GPIO 8 (SPI_CE0_N)
GROUND 25 26 GPIO 7 (SPI_CE1_N)
ID_SD 27 28 ID_SC
GPIO 5 29 30 GROUND
GPIO 6 31 32 GPIO 12
GPIO 13 33 34 GROUND
GPIO 19 35 36 GPIO 16
GPIO 26 37 38 GPIO 20
GROUND 39 40 GPIO 21

Related Links

Running Tests

To run the test suite first install the development dependencies:

npm install

then run the tests:

npm test