HiLetgo HC-05 Wireless Bluetooth RF Transceiver Master Slave Integrated Bluetooth Module 6 Pin Wireless Serial Port Communication BT Module for Ar...

well make sure it has 5v

The HiLetgo HC-05 Wireless Bluetooth RF Transceiver Master Slave Integrated Bluetooth Module left me unsatisfied. Despite its claims, the module's performance was inconsistent and unreliable. The master-slave integration proved to be problematic, as it frequently struggled to establish stable connections with other devices. The setup process was complicated, and the module's documentation lacked clarity, making it challenging for even experienced users to configure properly. The promised wireless Bluetooth functionality was undermined by frequent signal drops and poor range. Overall, this Bluetooth module failed to provide the seamless and dependable wireless communication it claimed, making it a regrettable choice for anyone seeking reliable Bluetooth integration for their projects.

A little rant coming up. In short, if you're thinking about this, then buy it. It works perfectly, and it's a great price. IF you were thinking of buying a different type of module, however, be careful. One module that is *flaming hot garbage is the AT-09, AKA MLT BT05 or the 4.1 BTE module. You can search online for a manual (one has been translated from mandarin, but you need to spend a while trying to find it) , and it will show how its supposed to work pinouts with confusing terminology. You'll be lucky setting it up and getting it into "AT" mode, a necessary step to getting it to function properly. I haven't tried other module types, but I wouldn't doubt that there are others like the AT-09 , so I can't stress enough to be careful that you aren't buying a malfunctioning module, or a notoriously bad module type like that of the AT-09 MLT BT05 4.1 BTE Thanks for your time

A simple bluetooth transceiver. I used it with a breadboard and an arduino and had it running in less than 15 minutes. It sends and receives and connected to my android phone the first time. Fairly short range, but good clear signal in its range. Google for some tutorials and documents, though. There's plenty out there, but this didn't come with any how-tos.

After searching through the web on how to use the HC-05, I ordered a few for a project. Eventually, I got the project working smoothly on an Arduino Uno. I designed a printed circuit board for a shield and have made several units. All work well. That is the good news. The bad news is it helps to be an electrical engineer with experience in embedded design. The various web sites were helpful, but most had errors. For example, some circuits did not use a level shifter for driving the RxD input or reading from TxD. Some level shifters are wired wrong and the choice of circuit can even slow down the fastest baud rates. Some Arduino Uno baud rates are not good choices because of clock frequency errors. If you run the HC-05 using hardware serial on an Uno, you have to pull the HC-05 out to program the Uno. Other websites either do not seem to understand the two modes of HC-05 operation, or at least they describe the poorly. One mode (power up while holding the button) enables a configuration mode that must be run at 38,400 Baud. After configuration, the other mode (for data transfer) runs at whatever baud rate was selected during configuration. My project actually lets the Uno power up the unit in the configuration mode, checks the configuration, then cycles the power to restart in the data transfer mode. Don't reconfigure the device every time you use it. That will probably burn out the nonvolatile memory that holds the parameters. Finally, Bluetooth itself can be tricky. I found that Windows 7 and Windows 10 can be finicky about connecting and disconnection with a Bluetooth device. Good luck with your project. It may take some effort to get everything working. So far, the modules, themselves, have all worked properly once I got the hardware and software designed properly.