RN-52 bluetooth module pins and their functions | applied electronics engineering


RN-52 bluetooth module pins and their functions

By Applied Electronics - Wednesday, May 3, 2017 No Comments
As was described in earlier post what is RN-52 is a complete bluetooth module to transmit and receive audio steams wirelessly. The module contains DSP chip that processes the incoming and outgoing audio signal, that is either, speech or music in different file format such as MP3, MP4 etc. Other bluetooth module exist such as HC-05 but they do not have DSP chips and so do not support audio steaming profiles.

The RN-52 has interfaces to support microphone and speaker, power supply connection and supports the following interfaces to communicate with other devices:
  1. Bluetooth
  2. UART
  3. USB
  4. SPI
  5. PCM
 The pins related to these functions are shown in the diagram below.

RN-52 bluetooth module pins and their functions

The pins labelled 1 are related to power. There is a 3.3V connection, GND connection and PWR_EN pin. The PWR_EN when high enables to write program into the RN-52 module.

The pins labelled 2 are general purpose Input/output(GPIO). There are 11 GPIO pins. Most of the GPIO has specific functions. Readers are referred to datasheet for more details and some of them are explained below. There is also one analog input/output pin(AIO).

The USB pins are used for device firmware upgrade(DFU) to upload/update firmware to RN-52. During this mode, the GPIO 3 is used in conjunction.

The UART pins or interface labelled as 4 along with GPIO 9 allows the user to program the RN-52 bluetooth module by sending/receiving commands to and fro serial communication. Another use of UART pin is to connect it to a microcontroller for issuing commands from the microcontroller.

The audio input/ouput pins are labelled 5 in the above picture. These pins are used to connect to microphone and speaker. The user can connect headphones or speakers and microphones directly to these port and can listen to music immediately. Two sets of speaker and mic is supported. One can also connect audio line driver IC for better audio quality.

The pins labelled 6 are for connecting two LEDs(LED0 and LED1). These leds indicate the status of the device. If both of the LEDs are flashing then it means they are RN52 bluetooth module is discoverable. If LED0 is flashing and LED1 is off then it means the device is connectable. Similarly, if LED0 is off and LED1 is flashing it means that the device is connected(paired).

The SPI pins labelled 7 are for usual SPI connection. These pins can be used for example to send audio codec from external device.

Similarly, the PCM(Pulse Code Modulation) pins labelled 8 are used for PCM audio codec from external device.


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