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A proof of concept to demonstrate that it's feasible to implement a RaspberryPi IO Plugin for Johnny-Five usingLinux-IO.

Tested on a Raspberry Pi 4 Model B with Node.js v16.0.0. Should function withNode.js v10 or higher.

Thepigpio C library is a prerequisitefor pi-io.

Run the following command to determine which version of the pigpio C libraryis installed:

pigpiod -v

For the Raspberry Pi Zero, 1, 2 and 3 V41 or higher of the pigpio C library isrequired. For the Raspberry Pi 4 V69 or higher is required.

If the pigpio C library is not installed or if the installed version is tooold, the latest version can be installed with the following commands:

sudo apt-get updatesudo apt-get install pigpio

Alternative installation instructions for the pigpio C library can be foundhere.

Warning: The pigpio C library contains a number of utilities. One of theseutilities is pigpiod which launches the pigpio C library as a daemon. Thisutility should not be used as the pi-io uses the pigpio C library directly.

npm install pi-io

*) Ping was tested with three HC-SR04 proximity sensors with varying degreesof success. One sensor functioned as expected. The second didn't timeout asit should but it's was possible to workaround the issue with software. Thethird sensor didn't function. The issues may be related to the fact that asingle pin is used for both trigger and echo.

To workaround these issues a controller was implemented that allows separatepins to be used for trigger and echo. The same three HC-SR04 proximity sensorsfunctioned well with this controller.

varfive=require('johnny-five');varPiIO=require('pi-io');varboard=newfive.Board({io:newPiIO()});board.on('ready',function(){varled=newfive.Led('GPIO17');led.pulse(1000);});

varfive=require('johnny-five');varPiIO=require('pi-io');varboard=newfive.Board({io:newPiIO()});board.on('ready',function(){varservo=newfive.Servo({pin:'GPIO27',type:"continuous"});servo.cw(0.8);});

varfive=require('johnny-five');varPiIO=require('pi-io');varboard=newfive.Board({io:newPiIO()});board.on('ready',function(){varproximity=newfive.Proximity({controller:PiIO.HCSR04,// Custom controllertriggerPin:'GPIO23',echoPin:'GPIO24'});proximity.on("change",function(){console.log("cm: ",this.cm);});});

Note that this circuit uses a single pin for trigger and echo. Whether or notthis functions correctly appears to be highly dependent on the particularHC-SR04 sensor being used. The circuit shown above that uses separate pins fortrigger and echo is far more reliable.

varfive=require('johnny-five');varPiIO=require('pi-io');varboard=newfive.Board({io:newPiIO()});board.on('ready',function(){varproximity=newfive.Proximity({controller:'HCSR04',pin:'GPIO25'});proximity.on("data",function(){console.log("cm: ",this.cm);});});

Additional examples can be found in theexample directory.