Bluetooth module HC-08 BLE 4.0

HC-08 Bluetooth module is a new digital transmission module, based on the Bluetooth Specification V4.0 BLE Bluetooth protocol.
Its wireless working frequency band is 2.4GHz ISM, and the modulation method is GFSK. 
The module's default transmit power is 4dBm. Receive sensitivity -93dBm. 
The module is compatible with both Android and Apple systems. In an open environment, it can communicate with iphone4s, to achieve ultra-long-distance communication of 80 meters. It also comes with an LED status indicator. When using, you can directly see the connection state of Bluetooth.
The module uses the CC2540F256 chip from TI, configured with 256K bytes of space, supporting the AT command. For need, the users can change the role (master or slave mode), baud rate of serial port, device name and other parameters, very flexible use. 

Technical Details

• Working voltage: DC 5V
• Working frequency band: 2.4G
• Air speed: 1Mbps
• Communication interface: UART3.3VTTL level
• Antenna interface: built-in PCB antenna
• Sleep current: 0.4μA
• RSSI support: not supported
• Receive sensitivity: -93dBm@1Mbps
• Communication level: 3.3V
• Bluetooth version: V4.0
• Modulation method: GFSK
• Transmit power: 4dBm (default)
• Reference distance: 80m
• Working temperature: -25℃ to +75℃
• Working humidity: 10% to 90%
• Storage temperature: -40℃ to +85℃
• Working current (excluding LED)
• Host not connected / connected: 21mA / 9mA
• Slave MODE0, not connected / connected: 8.5mA/9mA
• Slave MODE1, not connected / connected: 6μA ~ 2.6mA / 1.6mA
• Slave MODE2, not connected / connected: 0.4μA/1.6mA

Extra:

• Compatible with Android and Apple System
• Environmental-friendly

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The HC-08 is a Bluetooth Low Energy (BLE) 4.0 module that is commonly used for wireless communication in embedded systems, IoT devices, and Arduino projects. It is similar to the popular HM-10 module but has some differences in firmware and AT command structure.

Key Features of HC-08 BLE 4.0 Module:

• Bluetooth Version: BLE 4.0 (Bluetooth Low Energy)

• Operating Voltage: 3.3V (5V tolerant with level shifting)

• Communication: UART (Serial) interface

• Default Baud Rate: 9600 (configurable via AT commands)

• Range: Up to 30 meters (depending on environment)

• Works with: Smartphones (Android/iOS), PCs, and other BLE devices

• AT Commands: Used for configuration (e.g., changing device name, baud rate, MAC address)

Pinout of HC-08 Module:

Basic AT Commands for HC-08:

To enter AT command mode, send AT (should return OK).

• AT → Check if module is responsive.

• AT+NAME? → Get current device name.

• AT+NAME=NEW_NAME → Set a new device name.

• AT+BAUD? → Check current baud rate.

• AT+BAUD=1 → Set baud rate to 9600 (1=9600, 2=19200, etc.).

• AT+ROLE? → Check role (0=Slave, 1=Master).

• AT+RESET → Reboot the module.

How to Connect HC-08 to Arduino:

1. Wiring:

   • HC-08 TXD → Arduino RX (Pin 0 or SoftwareSerial)

   • HC-08 RXD → Arduino TX (Pin 1 or SoftwareSerial)

   • HC-08 VCC → Arduino 3.3V (or 5V with a voltage divider)

   • HC-08 GND → Arduino GND

2. Example Arduino Code (Using SoftwareSerial)

#include
SoftwareSerial BTSerial(10, 11); // RX, TX (connect HC-08 TX to 10, RX to 11)

void setup() {
Serial.begin(9600);
BTSerial.begin(9600);
Serial.println("HC-08 Test Ready!");
}

void loop() {
if (BTSerial.available()) {
Serial.write(BTSerial.read());
}
if (Serial.available()) {
BTSerial.write(Serial.read());
}
}

Troubleshooting Common Issues:

1. No Response to AT Commands?

   • Make sure EN/KEY is pulled HIGH before powering on.

   • Check baud rate (default is usually 9600).

   • Try AT+RESET if the module is unresponsive.

2. Connection Drops Frequently?

   • Ensure stable power supply (use a capacitor if needed).

   • Check for interference from other wireless devices.

3. Not Discoverable on Phone?

   • Ensure the module is not already connected to another device.

   • Reset the module (AT+RESET).

HC-08 vs. HM-10: