node-red-nodes/hardware/PiSrf/README.md

node-red-node-pisrf
===================

A <a href="http://nodered.org" target="_new">Node-RED</a> node for Raspberry Pi
to read range from an SRF05 Ultrasonic range sensor.

**Only** works with a Raspberry Pi.

Install
-------

Run the following command in your Node-RED user directory - typically `~/.node-red`

    npm install node-red-node-pisrf

Usage
-----

Raspberry Pi input from an SRF04 or SRF05 ultrasonic range finder.

The configuration requires two GPIO pin numbers, the trigger pin and the echo pin.
These can be any spare valid Pi GPIO pins. e.g.

        7,11

You can also set the repeat frequency of measurements - default 0.5 seconds.

Outputs a `msg.payload` with a number representing the range in cm.

Produces one measure every 0.5s (by default) - but only if the distance is different from the previous reading.

**Note:** we are using the actual physical pin numbers on connector P1 as they are easier to locate.