My HM-20 Bluetooth module disconnects after 28-30 seconds

Projects Networking, Protocols, and Devices
1

Hello everyone,

I'm working on a project in which I'm trying to send data from a sensor (an HC-SR04 ultrasound sensor) to an Arduino Uno (hereafter called "Arduino 1") and then process this data with Matlab software to represent it.

To make it wireless, I came up with the idea of ​​pairing them with Bluetooth modules.

Before purchasing the Bluetooth modules, I did a preliminary analysis of Bluetooth technology. Since I also want to use a second Arduino Uno (hereafter called "Arduino 2") to drive some motors, I realized that if I wanted to pair more than one Bluetooth module simultaneously and seamlessly, I needed the modules I purchased to have at least Bluetooth version 5.2.

I searched around and finally bought the HM-20 Bluetooth modules, which have Bluetooth 5.3, so I shouldn't have any problems.

So I managed to pair the HM-20 module of "Arduino 1" with the Matlab software. This way, Matlab was receiving data from the HC-SR04 sensor every 100ms or less and representing it in 3D.

The problem arose when, approximately 28 to 30 seconds after establishing the connection, the HM-20 module decided to automatically disconnect.

I've been looking for a solution for a few days now, and honestly, I haven't made much progress.

I'll share the latest thing I tried in case it helps:

  1. Since this is an application I want to use in "real time" (i.e., with data transmission less than 200 ms), I can't afford to pair it after it's unpaired. Pairing it again takes 1.5 seconds and slows down the rendering. If I later want to implement it with some real-time control, it's useless.

  2. I've tried sending a message every second from Matlab to the HM-20 module so it detects a connection and doesn't disconnect. But even though the module detects the Matlab message, it keeps disconnecting.

The firmware version for the HM-20 module is "HMSoft V109."

It looks like I need to configure some parameter for the HM-20 module, and I've been looking at the manufacturer's datasheet ("https://www.deshide.com/product-details_HM-20.html") but can't figure it out.

I'm still investigating.

Thank you very much in advance for your time and help. I sincerely appreciate any assistance.

2

It could be that Bluetooth is merely an innocent victim. The problem might be your code clogging Uno up with Strings, or it might be power supply, both of which are apparently secret.

3

@narpa For informed help, please read and follow the instructions in the "How to get the best out of this forum" post, linked at the head of every forum category.