HC-05 6pin BT Bluetooth Module with Button (Compatible versions Type-A)

SKU: FA2039-1
Bluetooth Protocol

Bluetooth V2.0 + EDR (Enhanced Data Rate)
Operating Voltage

3.6V – 6.0V DC
Operating Current

30mA (Average); < 10mA (Connected)
Logic Level

3.3V (5V tolerant VCC; Voltage divider recommended for RX)
Frequency

2.4GHz ISM Band
Default Baud Rate

9600 (Data Mode) / 38400 (AT Command Mode)
Default PIN / Password

1234 (or 0000)
Transmission Power

Class 2 (+4dBm)
Range

~10 Meters (30 feet) in open space
Interface

UART (6-Pin: VCC, GND, TXD, RXD, STATE, EN/KEY)
Product Description
The HC-05 (Type-A) is a highly reliable and industry-standard Bluetooth 2.0+EDR (Enhanced Data Rate) module designed for wireless serial communication. As a “Master/Slave” dual-role module, the HC-05 is superior to the HC-06 because it can not only receive connections from phones and PCs but can also proactively search for and connect to other Bluetooth devices.
The Type-A configuration is characterized by its high compatibility with various microcontroller ecosystems. It features an onboard button that facilitates entry into AT Command Mode, allowing users to customize parameters such as the device name, pairing password (PIN), and communication speed (Baud Rate). Built on a 6-pin breakout board with an integrated 3.3V LDO regulator, it is designed for “plug-and-play” use with 5V systems like Arduino and industrial controllers.
Key Features
  • Dual-Role Versatility: Can be configured via AT commands to act as a Master (initiates connections) or a Slave (receives connections).
  • Simplified Configuration: The onboard physical button allows for easy entry into configuration mode without complex hardware “jumping” or high-level coding.
  • High Compatibility: Optimized firmware ensures stable performance across a wide range of platforms including Arduino, STM32, Raspberry Pi, and PC-based serial terminals.
  • Robust Connection: Features GFSK modulation and Adaptive Frequency Hopping to minimize interference in crowded 2.4GHz environments.
  • Visual Status Indicator: An onboard LED provides real-time feedback: fast blinking (searching), slow blinking (AT mode), and double-blinking (paired/connected).
  • Safe Voltage Range: The baseboard handles 3.6V to 6V input, making it compatible with both battery power and standard USB power rails.
Usage Scenarios
  • Hobbyists & Makers: Wireless control of Arduino robots, smartphone-controlled LED lighting, and remote sensor data monitoring for weather stations.
  • Business & Commercial: Point-of-Sale (POS) wireless printing, industrial wireless debugging (avoiding long cable runs), and equipment-to-equipment serial communication in automated warehouses.
Q: What is the main difference between Type-A and Type-B HC-05 modules?

Both modules share the same core Bluetooth chip. The Type-A refers to the specific breakout board layout and firmware version, often noted for its high compatibility with standard Arduino libraries and specific AT command response timing.

Q: Can I connect this module to my iPhone or iPad?

No. The HC-05 uses “Bluetooth Classic.” Apple iOS devices only support “Bluetooth Low Energy” (BLE) for serial data. For iOS compatibility, please check our HM-10 or CC2541 modules. It works perfectly with Android, Windows, and macOS.

Q: How do I change the module from Slave to Master?

Enter AT Command Mode (hold the button while powering on) and send the command AT+ROLE=1. To switch back to Slave, use AT+ROLE=0.

Q: Do I need a logic level shifter for the RX/TX pins?

While the module is powered by 5V, the logic signals are 3.3V. While many users connect it directly to a 5V Arduino, it is best practice to use a simple voltage divider (1kΩ and 2kΩ resistors) on the RX line of the HC-05 to ensure long-term reliability.

Q: What do the "STATE" and "EN" pins do?

The STATE pin outputs a signal indicating if the module is connected (High) or disconnected (Low). The EN (Enable) or KEY pin is used to trigger AT Command Mode via software if you do not wish to use the physical button.

Q: Can I use this for high-speed file transfers?

The HC-05 is designed for Serial Pass-Through (text and small data packets). It is not suitable for streaming high-definition audio or large file transfers.

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