node-red-contrib-i2c 0.5.2

A Node-RED node to talk to the Raspiberry PI's I2C port

npm install node-red-contrib-i2c

This set of node-red nodes communicate with the Raspberry Pi I2C driver and uses the node-I2C package. Run the following command in the root directory of your Node-RED install, usually this is ~/.node-red.

As of version 0.5.0 the nodes are using the i2c-bus library to communicate with your devices. It looks more stable and up-to-date. Also the need to use a config-node is removed. The config node was needed to store the common i2c object. With the new i2c-bus library is that not needed anymore.

Warning: After upgrading to this version you will get an error of an unknown node in the config side-bar, you can safely remove this one.

Downside my nodes work only for newer version where the i2c driver is on /dev/i2c-1

npm install --unsafe-perm node-red-contrib-i2c


Provides three nodes - one to scan connected device, one to receive messages, and one to send.


When you start using on of the below nodes you need first to configurate the I2C Device. The Raspberry PI uses an special device name to connect to the I2C controller. Depending on the Raspberry PI version it can be one of the below values; for the RPi Rev 1 it /dev/i2c-0 and all Others it will be /dev/i2c-1 (=default). In the config screen you can also set the default I2C-address to where the node sends the Messages and request's to.

Scan I2C

This will scan the I2C bus for connected devices and has one in point to trigger the scan process and 2 out put points:

  • The first output point give a list of all found decives in msg.payload and will be triggered once.
  • The second output point will be triggered for every found device the address will be in msg.payload

Input I2C

This node will request data from a given device. The address and command can both be set in the dialog screen or dynamicly with msg.address and msg.command. This node outputs the result as a buffer in msg.payload and places the address in msg.address and command in msg.command.

Output I2C

This node will send a given String/array/buffer to a given device. The address and command can both be set in the dialog screen or dynamicly with msg.address and msg.command. The payload can be staticly or dynamicly (using msg.payload) set. This payload can be a Buffer, Array, String or Integer. When you use integers then the number of bytes to send is importend and can be set between 0 and 31 bytes.

NEW(0.5.0): you can daisychain this node, the input msg is send unchanged to the next node.

Inportend Note

Version v0.5.0 is now using the I2C-bus package from fivdi. It looks more robust and better for asyncrone processes like node-red. I would like the maker as much thanks for his work as Kelly in the past version. You can vind his work on github:

old version did use the work of kelly's I2C package to work. And i like to thank hem for the work he did on that package. For more info check out his github account at:

Node Info

Version: 0.5.2
Updated 1 month ago
License: Apache-2.0


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  • i2c scan
  • i2c in


  • node-red
  • node-red-contrib
  • i2c


  • nielsnl