Node-RED Flows
Connect the three circuits (Nano 1, Nano 2, and Pico) to the 3 USB ports on the Raspberry Pi or the personal computer running Node-RED and start the flows. You should start seeing the data published to the MQTT Broker.
Send data from the Node-RED flow to the Pico circuit which will read the data over the default Serial port and send control signals to the relay and motor.
To use Node-RED you need a computer and the circuits sending or receiving data need to be connected to the computer with an USB cable. This is an alternative approach to using wireless communication to send data to an MQTT broker over WiFi. The advantage of this approach is that you can configure Node-RED for the required functionality with very little code whereas if you want to use the ESP32 WiFi and MQTT capability you need to download libraries and write the required code.
For the solution variant that uses Node-RED, the ESP32 circuit is not required and neither is any inter-board communication. The Nano and Pico circuits will be connected to a Raspberry Pi and will exchange data directly with Node-RED.
We will be using a Raspberry Pi to run Node-RED but you can use your personal computer just as well.
The flows for each of the circuits are below:
Sensor Data Flow
The Node-RED flow for capturing sensor data from the Nano and Pico circuits is shown below.
Code
You can recreate the flow by importing the code below into your Node-RED editor.
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The Node-RED flow for sending control signals to the Nano circuit is shown below.
Code
You can recreate the flow by importing the code below into your Node-RED editor.
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