Bluetooth Module(HC-05)

Bluetooth HC-05 module is an easy to use Bluetooth SPP (Serial Port Protocol) module, designed for transparent wireless serial connection setup. Serial port Bluetooth module is fully qualified Bluetooth V2.0+EDR (Enhanced Data Rate) 3Mbps Modulation with complete 2.4GHz radio transceiver and baseband. It uses CSR Bluecore 04-External single chip Bluetooth system with CMOS technology and with AFH(Adaptive Frequency Hopping Feature). It has the footprint as small as 12.7mm x 27mm. 

Specifications

Hardware features

  •  Typical -80dBm sensitivity
  •  Up to +4dBm RF transmit power
  •  Low Power 1.8V Operation ,1.8 to 3.6V I/O
  •  PIO control
  •  UART interface with programmable baud rate
  •  With integrated antenna
  •  With edge connector

Software features

  •  Default Baud rate: 38400, Data bits:8, Stop bit:1,Parity:No parity, Data control: has. Supported baud rate: 9600,19200,38400,57600,115200,230400,460800.
  •  Given a rising pulse in PIO0, device will be disconnected.
  •  Status instruction port PIO1: low-disconnected, high-connected;
  •  PIO10 and PIO11 can be connected to red and blue led separately. When master and slave are paired, red and blue led blinks 1time/2s in interval, while disconnected only blue led blinks 2times/s.
  •  Auto-connect to the last device on power as default.
  •  Permit pairing device to connect as default.
  •  Auto-pairing PINCODE:”0000” as default
  •  Auto-reconnect in 30 min when disconnected as a result of beyond the range of connection.

HC-05 embedded Bluetooth serial communication module (can be short for module) has two work modes: order-response work mode and automatic connection work mode. And there are three work roles (Master, Slave and Loopback) at the automatic connection work mode. When the module is at the automatic connection work mode, it will follow the default way set lastly to transmit the data automatically. When the module is at the order-response work mode, user can send the AT command to the module to set the control parameters and sent control order. The work mode of module can be switched by controlling the module PIN (PIO11) input level. Serial module PINs: 

1. PIO8 connects with LED. When the module is power on, LED will flicker. And                   the flicker style will indicate which work mode is in using since different mode                   has different flicker time interval. 

2. PIO9 connects with LED. It indicates whether the connection is built or not. When the       Bluetooth serial is paired, the LED will be turned on. It means the connection is built         successfully. 

3. PIO11 is the work mode switch. When this PIN port is input high level, the work mode      will become order-response work mode. While this PIN port is input low level                    or suspended in air, the work mode will become automatic connection work mode. 

4. The module can be reset if it is re-powered since there is a reset circuit at the module. 

How Bluetooth Operates

Bluetooth networking transmits data via low-power radio waves. It communicates on a frequency of 2.45 gigahertz (actually between 2.402 GHz and 2.480 GHz, to be exact). This frequency band has been set aside by international agreement for the use of industrial, scientific and medical devices (ISM). A number of devices that you may already use take advantage of this same radio-frequency band. Baby monitors, garage-door openers and the newest generation of cordless  phones all make use of frequencies in the ISM band. Making sure that Bluetooth and these other devices don't interfere with one another has been a crucial part of the design process.

One of the ways Bluetooth devices avoid interfering with other systems is by sending out very weak signals of about 1 milliwatt. By comparison, the most powerful cell phones can transmit a signal of 3 watts. The low power limits the range of a Bluetooth device to about 10 meters (32 feet), cutting the chances of interference between your computer system and your portable telephone or television. Even with the low power, Bluetooth doesn't require line of sight between communicating devices. The walls in your house won't stop a Bluetooth signal, making the standard useful for controlling several devices in different rooms. Bluetooth can connect up to eight devices simultaneously. With all of those devices in the same 10-meter (32-foot) radius, you might think they'd interfere with one another, but it's unlikely.

Bluetooth uses a technique called spread-spectrum frequency hopping that makes it rare for more than one device to be transmitting on the  same frequency at the same time. In this technique, a device will use 79 individual, randomly chosen frequencies within a designated range, changing from one to another on a regular basis. In the case of Bluetooth, the transmitters change frequencies 1,600 times every second, meaning that more devices can make full use of a  limited slice of the radio spectrum. Since every Bluetooth transmitter uses spread-spectrum transmitting automatically, it’s unlikely that two transmitters will be on the same frequency at the same time. This same technique minimizes the risk that portable phones or baby monitors will disrupt Bluetooth devices, since any interference on a particular frequency will last only a tiny fraction of a second. 

When Bluetooth-capable devices come within range of one another, an electronic conversation takes place to determine whether they have data to share or whether one needs to control the other. The user doesn't have to press a button or give a command -- the electronic conversation happens automatically. Once the conversation has occurred, the devices -- whether they're part of a computer system or a stereo -- form a network. Bluetooth systems create a personal-area network (PAN), or piconet, that may fill a room or may encompass no more distance than that between the cell phone on a belt-clip and the headset on your head. Once a piconet is established, the members randomly hop frequencies in unison so they stay in touch with one another and avoid other piconets that may be operating in the same room.

PIN DESCRIPTION: 

 

Let's check out an example of a Bluetooth-connected system.

Category: 

tags: 

Share

Who's new

  • ravirajpatil871...
  • shubhambajoria
  • yassir
  • demiholyman890954
  • scottgillum51169040

Get Notified

 

Share

We are Social

Syndicate

Subscribe to Syndicate