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

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.

It's Amazing! Certainly recommended!

works great first try. easy to use. I connected this to my Arduino Uno R3 with a 1k and 2k resistor voltage divider on the rx pin. it ran with no errors for 16 continuous hours sending a serial message once per second. I only gave this a 4 star because it took 8 days to be delivered.

This is a great Bluetooth board. It worked very well with my arduino. Please note that it cannot interface with apple products since it uses an older version of Bluetooth that apple has deemed a security hazard so it won’t work with apple but it worked with my PC and my arduino.

As advertised, just what I needed, immediate shipping, thanks!

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 ̶h̶o̶w̶ ̶its ̶s̶u̶p̶p̶o̶s̶e̶d̶ ̶t̶o̶ ̶w̶o̶r̶k̶ 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 BTEThanks for your time

I can enter AT mode just fine, but the BIND command doesn't work at all. I bought 2, and neither will BIND to any address that I set. I'm doing the exact same as all the tutorials I can find and all the other AT commands I try seem to work, but no matter what address I enter with BIND, it will not change the random one that it shipped with. RESET doesn't change it, ORGL doesn't change it. These are useless to me without that capability. I ordered these for a school project and am probably going to fail because I don't have time to order more, and these don't work.

I though I was going to have to learn all about Bluetooth to use this, but I just connected it to my Arduino and used a serial terminal program on my computer or phone and I was able to send serial data. Very happy with the board. For my Android I'm using "Serial Bluetooth Terminal" which is great, and on the PC I'm using BlueDuino which kind of works. NOTE: This is Bluetooth, not BLE. Also, remember to swap TX and RX between the HC-05 and the Arduino.