HELP: Closed Sensor Network, 1 Central Receiver with Multiple Nodes

[itzgenx]

Hey guys, I am somewhat new to arduino here, and I had some questions regarding a project I am working on.

Firstly, the project description:

• 4x strain sensors with hx711 amplifier coupled to an arduino MCU transmitting recorded data wirelessly.
• Each of the 4 combos will be battery operated and attached to a spinning metal shaft of a moving vehicle.
• Data reporting is small being just one float value per node, but the reporting rate needs to be 10-80 times per second.
• 1x MCU receiving wireless data from all 4x sensor nodes. Data received will drive PWM outputs to the vehicle for an onboard gauge display.

I was gifted a handful of some Arduino Nano 33 Iot’s, and I was wondering if these little things can pull it off. I couldn’t figure out how to get 4x nodes to talk to one central unit wirelessly, nor could I find any decent examples of this over BLE or WiFi. I looked into mesh information for BLE and WiFi which the ESP chips seem capable of, but this board comes with a SAMD21 front end chip with the ESP32 chip crammed inside the U-Blox W102 module. This means we don’t have direct control of the ESP chip and any of its additional functions outside of the WiFiNINA library.

All examples and online material have only demonstrated how to control or send data over the internet to a smart device or wirelessly control the LED. Additionally, those examples found seem to focus on one device to another, not multiple devices fed into one central device.

So what’s the best method here? Is it even possible with this board? If so, please enlighten me.

As a bench test goal right now, I want to aim to utilize the onboard gyroscope readings of 4 boards to be simultaneously sent wirelessly to a central board with no outside devices involved (no computers, smart devices, routers). So what are your thoughts? Can this be done?

Thanks!

[Klaus_K]

Welcome to the forum.

@itzgenx

I looked into mesh information for BLE and WiFi which the ESP chips seem capable of,

Mesh technology is not necessary nor helpful for your case. You describe a classic star type network.

@itzgenx

battery operated and attached to a spinning metal shaft of a moving vehicle.

That means you need ultra-low power. That likely excludes WiFi. I have done some tests with multiple Arduinos running from a 18650 Lion and you get 24-50h of continuous run time sending a few values using MQTT protocol every minute.

That leaves you with BLE. Your data size and rate seem reasonable.

@itzgenx

attached to a spinning metal shaft of a moving vehicle.

That will require some testing. BLE has been designed for low power. A vehicle is full of metal, wires and is a notoriously noisy environment. Bluetooth Classic has been used in vehicles to connect phones to the car entertainment system. So, it could work, but then the phone is not attached to the drive shaft.

I recommend you search around for wireless automotive sensor frequencies e.g., for tire pressure sensors. See if you can find some that use 2.4GHz or whether they are all sub-GHz.

The other issue you will need to investigate is what device you can use a central. You need something that can handle multiple BLE connections. It does not make any difference for the peripheral side. Physically the most BLE enabled boards should be able to do this. However you will need to verify the library and software support. Most of them focus on one-to-one connections for examples. That is what most makers are happy with.