Specifications:

Documents:

• Datasheet
• Android chat Arduino by Bluetooth Bee

Product characteristics:
1, the core module using the HC-05 from the module, the lead interface includes VCC, GND, TXD, RXD, KEY pin, Bluetooth connection status pins (STATE), the output is low, the output is high after the connection
2, LED indicates the Bluetooth connection status, the flash indicates that there is no Bluetooth connection, the slow flash to enter the AT mode, the double flash indicates that Bluetooth has been connected and opened the port
3, the base plate is provided with anti reverse connection diode, with LDO 3.3V, input voltage of 3.6 ~ 6V, the current is about 30mA, when the pairing is about 10mA, the input voltage is forbidden to exceed 7V!
4, interface level 3.3V, can be directly connected to a variety of single-chip (51, AVR, PIC, ARM, MSP430, etc.), 5V can also be directly connected, no need to MAX232 also can not go through MAX232!
5, open and effective distance of 10 meters (power level of CLASS 2), more than 10 meters is also possible, but not to the quality of the connection to do this distance
6, after the pair when a full duplex serial port to use, no need to know any Bluetooth protocol, support 8 data bits, 1 stop bit and parity of the communication format can be set, which is the most commonly used communication format does not Support other formats.
7, you can pull up to 34 feet into the AT command mode settings parameters and query information
8, small size (3.57cm * 1.52cm), the factory patch production, to ensure the quality of the patch. A transparent heat shrinkable tube, dustproof appearance, and anti-static ability.
9, through the AT command to switch to the host or slave mode, can be connected to the specified device through the AT command
10, support from the 4800bps ~ 1382400bps standard baud rate

Product use:
Paired only need as the serial baud rate is fixed as can be used, so as long as it is to the "fixed baud rate, 8 data bits, no parity" communication format of serial device can directly replace the original wired serial without the need To modify the program. Such as data acquisition, smart cars, serial printers, outdoor dot matrix screen control, etc ..
Matching with the computer: suitable for computer and equipment through the Bluetooth serial communication, the use of the same method with the serial port
Pairing with mobile phones: suitable for mobile phones and devices through the Bluetooth serial communication, the use of the same method with the serial port
Bluetooth host matching with the use: suitable for two devices directly through the Bluetooth serial communication, such as single-chip and single-chip, between the cable with the microcontroller, the use of the method and the serial port

Flexible use:
Baud rate transform, because the sender and the receiver can choose their own baud rate, when a small amount of data can be used as a baud rate transform equipment.

The nRF24L01 is a highly integrated, ultra low power (ULP) 2Mbps RF transceiver IC for the 2.4GHz ISM (Industrial, Scientific and Medical) band. With peak RX/TX currents lower than 14mA, a sub μA power down mode, advanced power management, and a 1.9 to 3.6V supply range, the nRF24L01 provides a true ULP solution enabling months to years of battery lifetime when running on coin cells or AA/AAA batteries. The Enhanced ShockBurst™ hardware protocol accelerator additionally offloads time critical protocol functions from the application microcontroller enabling the implementation of advanced and robust wireless connectivity with low cost 3rd-party microcontrollers.

The nRF24L01 integrates a complete 2.4GHz RF transceiver, RF synthesizer, and baseband logic including the Enhanced ShockBurst™ hardware protocol accelerator supporting a high-speed SPI interface for the application controller. No external loop filter, resonators, or VCO varactor diodes are required, only a low cost ±60ppm crystal, matching circuitry, and antenna.

The Nordic nRF24L01 is available in a compact 20-pin 4 x 4mm QFN package.

Статья Работа с Bluetooth модулем HC05
Статья Модуль Bluetooth HC-04 на чипе BC417143B компании CSR

root@raspberrypi:~# iwlist wlan0 freq
wlan0     14 channels in total; available frequencies :
          Channel 01 : 2.412 GHz
          Channel 02 : 2.417 GHz
          Channel 03 : 2.422 GHz
          Channel 04 : 2.427 GHz
          Channel 05 : 2.432 GHz
          Channel 06 : 2.437 GHz
          Channel 07 : 2.442 GHz
          Channel 08 : 2.447 GHz
          Channel 09 : 2.452 GHz
          Channel 10 : 2.457 GHz
          Channel 11 : 2.462 GHz
          Channel 12 : 2.467 GHz
          Channel 13 : 2.472 GHz
          Channel 14 : 2.484 GHz
          Current Frequency:2.412 GHz (Channel 1)