Getting Started with Node-RED using BEVRLink 4/8-Channel Relay Hat for Raspberry Pi

Welcome to our guide on getting started with Node-RED using the BEVRLink 4/8-Channel Relay HAT for Raspberry Pi!

This tutorial will walk you through the process of setting up and configuring your Raspberry Pi to control relays using Node-RED, making it perfect for home automation projects, IoT applications, and more.

For this we have connected a Raspberry Pi 5 to the BEVRLink Raspberry Pi 5 8 Channel Relay 12V. With this relay module board you need the BEVRLink Power Supply 12V 2A. 

This guide works for BEVRLink Raspberry Pi 5 4 Channel Relay, just omit the relay 5-8 and the status LED from the code. With this relay module you can either power the Raspberry Pi directly or back feed it from a connected BEVRLink relay Module through the Expansion Connector.

Optional for a safe setup we recommend to use case for both the manager and relay boards: BEVRLink Cases

What You Will Need

• Raspberry Pi (any model with GPIO pins)
• BEVRLink 4/8-Channel Relay HAT
• MicroSD card (16GB or larger) with Raspberry Pi OS installed
• Power supply for the Raspberry Pi
• Internet connection
• Node-RED installed on your Raspberry Pi

Pinout Configuration

Here’s the pinout configuration for connecting the BEVRLink Relay HAT to your Raspberry Pi:

Additionally, more relays can be connected using I2C expanders, allowing for efficient control and communication with multiple relays.

Step-by-Step Guide

1. Set Up Your Raspberry Pi

If you haven’t already, set up your Raspberry Pi by following these steps:

• Download and install Raspberry Pi OS on your microSD card.

Enable SSH

To enable SSH, you need to place an empty file named ssh (without any extension) into the boot partition of your microSD card. Here’s how:

1. Insert the microSD card into your computer.
2. Open the boot partition (it should be labeled boot or similar).
3. Create a new empty file and name it ssh (make sure there is no file extension).
4. Safely eject the microSD card and insert it into your Raspberry Pi.

Connect to Your Raspberry Pi via SSH

1. Power up your Raspberry Pi and connect it to your network (via Ethernet or Wi-Fi).
2. Find the IP address of your Raspberry Pi. You can do this by checking your router’s connected devices list or using a network scanning tool like nmap.
3. Open a terminal on your computer and connect to your Raspberry Pi using SSH:

   ssh pi@<your_pi_ip_address>
   

4. When prompted, enter the default password (raspberry), or the password you set during setup.

2. Install Node-RED

To install Node-RED, open a terminal on your Raspberry Pi (via SSH) and run the following commands:

bash <(curl -sL https://raw.githubusercontent.com/node-red/linux-installers/master/deb/update-nodejs-and-nodered)

This script will install Node-RED and Node.js on your Raspberry Pi. Once installed, you can start Node-RED by running:

node-red-start

Access Node-RED in your browser by navigating to http://<your_pi_ip_address>:1880.

3. Configure GPIO in Node-RED

Node-RED provides a powerful interface to control the GPIO pins on your Raspberry Pi. To get started, follow these steps:

• Open Node-RED in your browser.
• Go to the menu (three horizontal bars) and select Manage palette.
• Search for the node-red-node-pi-gpio package and install it.

4. Connect the Relay HAT

Carefully place the BEVRLink Relay HAT onto the GPIO pins of your Raspberry Pi, ensuring that the pins align correctly.

5. Create Your First Flow

With Node-RED, you can create flows to control your relays. Here’s a simple example to turn on Relay Channel 1:

1. Drag an inject node (found under the input category) to the workspace.
2. Drag a rpi gpio out node (found under the raspberry pi category) to the workspace.
3. Connect the inject node to the rpi gpio out node.
4. Double-click the rpi gpio out node and configure it:
   • Select GPIO5 (corresponding to RPI Pin 29, BCM Pin 5).
   • Set the Type to Digital Output.
   • Set the Initial state to Low (0).
   • Set the Payload to High (1) to turn on the relay.
5. Deploy your flow and test it by clicking the inject button.

6. Control I2C Connected Relays

To control additional relays connected via I2C expanders, you need to install the appropriate Node-RED nodes for I2C communication. Follow these steps:

1. Install the I2C nodes by opening the Node-RED palette manager:

   • Go to the menu (three horizontal bars) and select Manage palette.
   • Search for node-red-contrib-i2c and install it.

2. Connect your I2C expander and identify its I2C address. You can use the i2cdetect tool in the terminal:

   sudo apt-get install -y i2c-tools
   sudo i2cdetect -y 1
   

3. Create a flow to control the I2C relays:

   • Drag an inject node to the workspace.
   • Double-click the inject node to configure it:
     • Name: Set a descriptive name for the action (e.g., Configure Relay 4 ch Outputs).
     • Payload: Set the payload to the desired buffer values (e.g., Buffer [3, 0]).
     • Payload Type: Choose buffer from the dropdown menu.
   • Drag an i2c out node to the workspace.
   • Connect the inject node to the i2c out node.
   • Double-click the i2c out node and configure it:
     • Set the I2C address to the address of your expander.
     • Set the Bus to 1 (if using the default I2C bus).
     • Set the Send bytes to 2.

Configuration Details

4. Deploy your flow and test it by clicking the inject button.

Conclusion

Controlling relays with Node-RED and the BEVRLink Relay HAT opens up a world of possibilities for your Raspberry Pi projects. Whether you’re automating your home, building smart devices, or experimenting with IoT, this setup provides a versatile and powerful platform. Adding I2C expanders allows for even more relays to be controlled efficiently.

We hope this guide helps you get started with your Node-RED and Raspberry Pi relay control project. If you have any questions or need further assistance, feel free to reach out to our support team. Happy tinkering!

Example Flow Configuration

Relay 4 ch (PCA9554)

1. Inject Node:

   • Name: Configure Relay 4 ch Outputs
   • Payload: Buffer [3, 0]
   • Payload Type: buffer

2. I2C Out Node:

   • Name: Relay 4 ch I2C Out
   • Bus: 1
   • Address: 56
   • Send bytes: 2

Connect the inject node to the i2c out node.

Turn On Relay Channel 1 for Relay 4 ch

1. Inject Node:

   • Name: Turn On Relay 4 ch Channel 1
   • Payload: Buffer [1, 1]
   • Payload Type: buffer

2. I2C Out Node:

   • Bus: 1
   • Address: 56
   • Send bytes: 2

Turn Off Relay Channel 1 for Relay 4 ch

1. Inject Node:

   • Name: Turn Off Relay 4 ch Channel 1
   • Payload: Buffer [1, 0]
   • Payload Type: buffer

2. I2C Out Node:

   • Bus: 1
   • Address: 56
   • Send bytes: 2

Relay 8 ch (MCP23008)

1. Inject Node:

   • Name: Configure Relay 8 ch Outputs
   • Payload: Buffer [0, 0] (to set all pins as outputs)
   • Payload Type: buffer

2. I2C Out Node:

   • Name: Relay 8 ch I2C Out
   • Bus: 1
   • Address: 32
   • Send bytes: 2

Connect the inject node to the i2c out node.

Turn On Relay Channel 1 for Relay 8 ch

1. Inject Node:

   • Name: Turn On Relay 8 ch Channel 1
   • Payload: Buffer [9, 1] (9 is the GPIO register address)
   • Payload Type: buffer

2. I2C Out Node:

   • Bus: 1
   • Address: 32
   • Send bytes: 2

Turn Off Relay Channel 1 for Relay 8 ch

1. Inject Node:

   • Name: Turn Off Relay 8 ch Channel 1
   • Payload: Buffer [9, 0] (9 is the GPIO register address)
   • Payload Type: buffer

2. I2C Out Node:

   • Bus: 1
   • Address: 32
   • Send bytes: 2

Using GPIO Nodes to Control Relays

In addition to using the I2C nodes, you can also control the relays via GPIO nodes in Node-RED.

Example GPIO Flow Configuration

1. Inject Node:

   • Name: Turn On Relay GPIO
   • Payload: 1
   • Payload Type: num

2. GPIO Out Node:

   • Pin: The GPIO pin number corresponding to the relay channel.
   • Name: Relay GPIO Out
   • Type: Digital Output
   • Initial Level: Low

Connect the inject node to the GPIO out node.

Turn Off Relay GPIO

1. Inject Node:

   • Name: Turn Off Relay GPIO
   • Payload: 0
   • Payload Type: num

2. GPIO Out Node:

   • Pin: The GPIO pin number corresponding to the relay channel.
   • Name: Relay GPIO Out
   • Type: Digital Output
   • Initial Level: Low

Deploy and Test

1. Deploy the Flow in Node-RED.
2. Trigger the Inject Nodes:
   • Trigger Configure Relay 4 ch Outputs first.
   • Trigger Turn On Relay 4 ch Channel 1.
   • Trigger Turn Off Relay 4 ch Channel 1.
   • Similarly, test the Relay 8 ch configuration.
   • Trigger Turn On Relay GPIO.
   • Trigger Turn Off Relay GPIO.

This setup ensures the PCA9554 and MCP23008 are configured, and the relay channels can be controlled via Node-RED. If you encounter any issues, double-check the configurations and connections.