node-red-node-pi-gpio

node-red-node-pi-gpio

A set of Node-RED nodes to interact with Pi GPIO using the RPi.GPIO python library that is part of Raspbian.

It also include a simple node that detect mouse buttons and also keyboard clicks. Note: this picks up mouse keys direct from the keyboard so should work even when the app does not have focus, but YMMV.

If you need servo control then look at the node-red-node-pi-gpiod node as this is a lot more accurate timing wise, and more suitable for driving servos

Install

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

    npm i node-red-node-pi-gpio

The python library may also work with other distros running on a Pi (like Ubuntu or Debian) - you will need to install the PIGPIO package and run the following commands in order to gain full access to the GPIO pins as this ability is not part of the default distro. This is NOT necessary on Raspbian.

    sudo apt-get install python-pip python-dev
    sudo pip install RPi.GPIO
    sudo addgroup gpio
    sudo chown root:gpio /dev/gpiomem
    sudo adduser $USER gpio
    echo 'KERNEL=="gpiomem", NAME="%k", GROUP="gpio", MODE="0660"' | sudo tee /etc/udev/rules.d/45-gpio.rules
    sudo udevadm control --reload-rules && sudo udevadm trigger

Usage

Note: the diagram in the configuration shows pin numbers - the BCM GPIO field allows you to enter the GPIO number directly (this allows you to use the node for other devices that have other BCM GPIO like the Pi Compute modules.)

Input node

Generates a msg.payload with either a 0 or 1 depending on the state of the input pin.

Outputs

• msg.payload - number - the level of the pin (0 or 1)
• msg.topic - string - pi/{the pin number}

You may also enable the input pullup resistor ↑ or the pulldown resistor ↓.

Output node

Can be used in Digital or PWM modes.

Input

• msg.payload - number | string
• Digital - 0, 1 - set pin low or high. (Can also accept boolean true/false)
• PWM - 0 to 100 - level from 0 to 100%

Hint: The range node can be used to scale inputs to the correct values.

Digital mode expects a msg.payload with either a 0 or 1 (or true or false), and will set the selected physical pin high or low depending on the value passed in.

The initial value of the pin at deploy time can also be set to 0 or 1.

When using PWM mode, the input value should be a number 0 - 100, and can be floating point.