Small experiments with the Nordic Semiconductor nRF24L01+ radio transceivers

The files here are a test project that I built to help me get to grips with the RF24 library on Raspberry Pi and on the embedded Arduino ATTiny84 chip.

multiColouredLedInterface.cpp is command line interface for the Raspberry Pi to set it up as a base node and then send a RGB colour code to the connected sensor node.

RGBLed.ino is an Arduino sketch that recieves the number, translates it into its respecting red, green and blue values then outputs these values (pwm) to the pins of an RGB led accordingly

webaccess.js is a node.js script that provides api-like ability to set the led colour

lightapp is a folder containing an node/express/socketio project that provies a web-inteface colour picker to set the colour

Example Usage

Set colour to white

$ ./multiColouredLedInterface -v 255255255

Set colour to green

$ ./multiColouredLedInterface -v 255000

This can also be called by other programs and I am aiming to write a webpage with a colour picker (in node.js) so that the colour of the LED will change as the user moves their mouse.

I have now written both an api-like webpage to set the colour and a webapp to change the colour using a colour picker. webaccess.js should be placed in the same directory as multiColouredLedInterface

Launch the api like so...

$ sudo node webaccess.js 3000

Where 3000 is the port number that you wish to start the server on

Set the colour to green

http://ip-address:portno/api/setcol?v=255000

This will return a JSON object in the form { 'color': colorcode } and set the led colour to the code specified

To launch the lightapp webapp

sudo npm start

This requires all the depenancies to have been downloaded first and will currently launch using nodemon as this tracks file changes and restarts the server when one occours as this is useful for development. Once launched going to http://ip-address:3000 will start a web inteface with a colour picker that will set the colour as the user moves the dot or slider.

The addresses are currently fixed and assigned in the code but they could easily be passed as a command line argument to control multiple nodes individually.

Requirements

RF24 Library for Raspberry Pi and Arduino (incliding ATTiny) - https://github.com/TMRh20/RF24