5PCS HC-05 Wireless Bluetooth Receiver RF Serial Transceiver Module Master Slave Integrated Bluetooth Module 6 Pin Wireless Serial Port Communication BT Module

This set of Bluetooth modules is a great set for anyone who wants to learn how they work. I would highly recommend.

script to write device name./** David Dold* JDDL Design, LLC** HC-06 differs from an HC-05. HC-06 are slave only devices, whereas HC-05 can be master or slave.* By default, no BT connection, an HC-06 device in AT mode @ 9600 baud between** An HC-06 does not respond to "AT"** The response from an HC-06 device for "AT+NAMEwhatever" is OKsetname** LEDs flashing on the HC-06 indicate command mode, steady indicate a BT connection.** NOTE: If you maintain a BT connection, via a terminal session or mobile app, then the AT commands* will simply transmit to the connected device.** The HC-06 spoc sheet calls for divided resistors and RX, I've never done it...** TROUBLESHOOTING* If you are unable to get this to work, confirm your rx/tx pins are correct. Confirm your wiring with a Serial BT Terminal.* On Android there are many to choose from. Pair your HC-06 with your phone, then connect to the device via the BT terminal app,* LEDs on HC-06 go solid. Run this sketch. Characters sent from the send textbox via the serial monitor or sent from the app,* echo on the opposing device. If your characters do not appear, re-check your wiring (hint is tx/rx reversed?).** If you are using seperate power supplies for your Arduino device -and- the HC-06, the grounds must be bonded.** Setting baud rate is for the hardware connection between* processor pid and the HC-06 device. BT connection is negotiated* between radios.*/#include <SoftwareSerial.h>#define BLUETOOTH_TX 10#define BLUETOOTH_RX 9#define BAUDRATE 9600SoftwareSerial bluetooth(BLUETOOTH_RX, BLUETOOTH_TX);void setup(){Serial.begin(BAUDRATE);Serial.println("ready");pinMode(BLUETOOTH_RX, INPUT);pinMode(BLUETOOTH_TX, OUTPUT);//setup bluetoothbluetooth.begin(BAUDRATE);bluetooth.flush();delay(1000);bluetooth.write("AT+NAMELifeMCP");}void loop(){//optionally, send characters via the SerialMonitor, this can be commented out and the bluetooth.write in setup() works.//outbound to HC-06if(Serial.available()){Serial.println("writing to bt");while (Serial.available())bluetooth.write(char(Serial.read()));}//inbound from HC-O6if(bluetooth.available()){Serial.println("BT Response");while (bluetooth.available()){delay(3);Serial.print((char)bluetooth.read());}Serial.println();}}

Received and out of the box one of them was completely DOA.The other 4 worked to start off. But once I actually started to use them the issues began.Setting the baud rate using the AT+BAUD2 command the rate should be 2400 baud. But once you actually set it to that and restart it will only respond to the "AT" command. No other command will ever return anything but errors.Now I have three dead bluetooth modules that I can only get "OK" responses from and are unable to accept/recv any other AT command.Also to top all of that off, they are not actually compatible with the HM-10 modules AT commands. They use their own subset of AT commands which are not even accurate to the "AT+HELP" commands output so even the firmware is garbage.Don't waste your time on these modules. Buy something you can reflash/program if you have to that doesn't require a 4k$ compiler to do so.

I'm using this with an arduino to communicate with an OBD2 ELM327 in my car. The older HC-05 I used were version 2.0. These are version 5.0. The big difference for me is that the older HC-05 required an '$' to be prepended to commands intended to be passed-through to the ELM327. But the newer version 5.0 HC-05 units do not require it and just pass-through everything.The other issue Im working is that these newer units don't like the AT-INIT command for some reason. More later...

These are the master versions allowing connections to your Arduino projects. HC-06 is the Slave version. These all work as advertised and are easy to add to your project. Don't forget the passwords for base module is "1234"

Out of 5 units, 1 was DOA, 1 had burned out LED, and 4 don't work much below 4 volts.Returned.Also, CSR chip is much smaller than typical HC-05.Incidentally, FW version is: 5.0-20220104

Work better than the H05!

On the HC-06, you can change baudrate and it will be saved in flash so you only need to set it once. However, the throughput is absolutely terrible. There is the reason they use 9600 baud as the default. Once the tiny 128 byte buffer is full it will miss sending out data. Don't use this for any kind of streaming data.