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node-red-node-arduino

A Node-RED node to talk to an Arduino running standard firmata 2.2 or better.

Install

Either use the Menu - Manage Palette option or run the following command in your Node-RED user directory - typically ~/.node-red

    npm i --unsafe-perm node-red-node-arduino

Usage

The Firmata firmware must be loaded into the Arduino.

See the main documentation for details and examples of how to use this node.

Input Node

Connects to local Arduino and monitors the selected pin for changes.

You can select either Digital, Pullup, Analogue, or String input type. Outputs the value read as msg.payload and the pin number as msg.topic.

It only outputs on a change of value - fine for digital inputs, but you can get a lot of data from analogue pins which you must then handle. For example you could use a delay node set to rate limit and drop intermediate values, or an rbe node to only report when it changes by a certain amount.

Output Node

Connects to local Arduino and writes to the selected pin.

You can select

  • Digital - accepts 0, 1, true, false, on, off
  • Analogue (PWM) - accepts Integer 0 to 255
  • Servo - accepts Integer 0 - 180
  • String - to send a String to the Arduino

Expects a numeric value in msg.payload. The pin number is set in the properties panel.

Note - some servos will not travel a full 180 degree range so may only accept 30 - 150 degrees for example. Please use the range node to scale the input appropriately.

Example

Simple flow to blink Pin 13

    [{"id":"d7663aaf.47194","type":"arduino-board","device":""},{"id":"dae8234f.2517e","type":"inject","name":"0.5s tick","topic":"","payload":"","payloadType":"date","repeat":"0.5","crontab":"","once":false,"x":150,"y":100,"z":"359a4b52.ca65b4","wires":[["56a6f8f2.a95908"]]},{"id":"2db61802.d249e8","type":"arduino out","name":"","pin":"13","state":"OUTPUT","arduino":"d7663aaf.47194","x":570.5,"y":100,"z":"359a4b52.ca65b4","wires":[]},{"id":"56a6f8f2.a95908","type":"function","name":"Toggle output on input","func":"\n// If it does exist make it the inverse of what it was or else initialise it to false\n// (context variables persist between calls to the function)\ncontext.level = !context.level || false;\n\n// set the payload to the level and return\nmsg.payload = context.level;\nreturn msg;","outputs":1,"noerr":0,"x":358,"y":100,"z":"359a4b52.ca65b4","wires":[["2db61802.d249e8"]]}]