Trying Out Accelerometers Part 2 (MPU6050 & Node-RED MCU)

2026年2月24日 2026年2月24日

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This article is translated from Japanese to English.

https://404background.com/program/mpu6050-2/

Introduction

In the previous post, I used an ESP32 and the MPU6050 accelerometer with code written in the Arduino IDE. This time, I will be using Node-RED MCU. With Node-RED MCU, you can flash programs created in the Node-RED editor directly onto a microcontroller.

▼For more details on Node-RED MCU, please refer to this post:

▼For the setup environment of Node-RED MCU (I am using a Raspberry Pi again):

▼The previous article (the circuit remains the same):

Retrieving Sensor Values

Configuring the Sensor Node

We will use the "Sensor" node provided by Node-RED MCU to retrieve the accelerometer data.

▼Place a Sensor node and select the sensor type.

▼In this case, we use "MPU6050" by InvenSense.

▼Once selected, you can configure detailed settings. The default address is 0x68.

Displaying in the Debug Window

Let's display the data in the debug window by connecting an inject node and a debug node.

▼The flow on the ESP32 side:

The inject node (labeled "timestamp") triggers the Sensor node at regular intervals.
▼Configure the "Repeat" field at the bottom. Note that if the time interval is too short, the microcontroller may fail to process the requests.

▼In the debug node, set it to "complete msg object" to view everything.

▼The debug window output looks like this:

From the debug output, we can see that the X-axis acceleration is stored in msg.payload.accelerometer.x. Since receiving all data at once can be hard to handle, let's try displaying only the X-axis acceleration.

▼By specifying msg.payload.accelerometer.x in the debug node, you can isolate the X-axis value.

▼The sensor values are also displayed in "xsbug," the debugging tool for Moddable.

Creating Graphs in Node-RED

We will send the accelerometer data via MQTT and visualize it on the Node-RED side. Here, I am sending data to an "Aedes MQTT broker" running on Node-RED.

▼Article on MQTT communication with Node-RED:

▼The flow on the Node-RED side. Ensure the topics in the mqtt in/out nodes match those on the ESP32 side.

As confirmed in the debug window, the X-axis acceleration can be accessed via msg.payload.accelerometer.x. We will send this value to a node for graphing.

▼The configuration of the change node: I've also prepared nodes for the Y and Z axes.

Next, configure the Node-RED Dashboard. I used the gauge and chart nodes from node-red-dashboard.
▼Most settings are default except for groups, but you can customize the type, color, label, and units.

Open the Dashboard screen to view the graphs.
▼You can open it from the Dashboard tab on the right side of the Node-RED editor.

▼The final graphs look like this. It makes me want to display them on a circular display!

▼Video of the system in action:

Finally

I successfully created a program for the accelerometer using Node-RED MCU and visualized the data in Node-RED. Although the exact units weren't explicitly stated, the value in the direction of gravity was roughly 9.8, so I assume it is in m/s².

One thing to note is that it doesn't work well if the processing speed is too high. At one point, the main Node-RED instance running the MQTT broker even stopped responding. While this setup is fine for environmental sensors like temperature and humidity which require slow update rates, Node-RED might not be the best choice for accelerometers in scenarios requiring high-speed responsiveness.

However, since it accurately detects the direction of gravity, it seems very useful for applications like tilting a display based on its orientation!