Microchip Technology RN52 Users manual

RN52 Bluetooth Audio Module

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Features:

• Fully qualified Bluetooth® version 3.0 module,
fully compatible with Bluetooth version 2.1+EDR,

1.2, and 1.1

• Software configurable through commands over
UART console interface

• Dedicated GPIO pins enable MCUs to access
control and status functions efficiently

• Postage-stamp-sized form factor, 13.5 x 26.0 x

2.7 mm

• Embedded Bluetooth stack profiles: A2DP,
AVRCP, HFP/HSP, and SPP

• Dual-channel, differential audio input and output
for highest quality audio

• Supports iAP profile to discover iOS devices and
apps (requires a special firmware build)

• Integrated amplifier for driving 16 Ω speakers

• UART (SPP) data connection interfaces

• External audio CODECs supported via S/PDIF

2

S interface

and I

• Castellated SMT pads for easy and reliable PCB
mounting

• Environmentally friendly, RoHS compliant

• Certifications: FCC, ICS, CE

• Bluetooth SIG certified

RN52 Block Diagram:

RN52

2 LEDs

MIC

MIC

PCB Antenna

Bluetooth 3.0
RF Baseband

Audio DSP

16-Bit Stereo

CODEC

RN52-DS

Speake

Speake

UART

USB

Applications:

• High-quality, 2-channel audio streaming

• Wireless stereo headsets

I2S

S/PDIF

16-Bit RISC MCU

16-MBit Flash

11 GPIO

Pins

1 AIO

• Automotive hands free audio

• Wireless audio docking station for smartphones

• Wireless speakers

• Intercom push-to-talk audio connection

• Remote control for media player

• Medical devices

• Computer accessories

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Advanced Information

RN52-DS

1.0 DEVICE OVERVIEW

Roving Network’s RN52 Bluetooth audio module pro­vides a highly integrated solution for delivering high­quality stereo audio in a small form factor. It combines
a class 2 Bluetooth radio with an embedded DSP pro­cessor. The module is programmed and controlled with
a simple ASCII command language.

The RN52 module complies with Bluetooth specifica­tion version 3.0. It integrates RF, a baseband controller,
etc., making it a complete Bluetooth subsystem. The
RN52 supports a variety of profiles including HSP/HFP,
A2DP, AVRCP, SPP, and iAP. It provides a UART inter­face, several user programmable I/O pins, stereo
speaker outputs, microphone inputs, and a USB port.

Ta bl e 1 -1 provides the general specifications for the

module. Ta b le 1 -2 and Table 1-3 provide the module’s
weight, dimensions, and electrical characteristics.

TABLE 1-1: GENERAL SPECIFICATIONS

Specification Description

Standard Bluetooth 3.0, class 2

Frequency Band 2.4 ~ 2.48 GHz

Modulation Method GFSK, PI/4-DQPSK, 8 DPSK

Maximum Data Rate 3 Mbps

RF Input Impedance 50 ohms

Interface UART, GPIO, AIO, USB, SPI, speaker, microphone

Operation Range 10 meters (33 feet)

Sensitivity -85 dBm at 0.1 % BER

RF TX Power 4 dBm

TABLE 1-2: WEIGHT & DIMENSIONS

Specification Description

Dimensions 26.0 mm x 13.5 mm x 2.7 mm

Weight 1.2 g

TABLE 1-3: ELECTRICAL CHARACTERISTICS

Specification Description

Supply Voltage 3.0 ~ 3.6 V DC

Working current Depends on profiles, 30 mA typical

Standby current (disconnected) < 0.5 mA

Temperature -40ºC to +85ºC

ESD JESD22-A224 class 0 product

Humidity 10% ~ 90% non-condensing

Figure 1-1 shows the module’s dimensions and
Figure 1-2 shows recommended landing pattern and

layout.

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Advanced Information

FIGURE 1-1: MODULE DIMENSIONS

0.00

2.55

0.85

3.75

4.95

6.15

7.35

8.55

9.75

10.95

12.65

13.50

0.0

26.00

PCB Outline: +/- 0.13 mm
PCB Thickness: +/- 0.100 mm

Tolerances:

(Top View)

Dimensions are in millimeters

21.20

21.40

20.00

18.80

17.60

16.40

15.20

14.00

12.80

11. 60

10.40

9.20

8.00

6.80

5.60

4.40

3.20

2.00

(Side View)

26.00

21.40

0.70

0.00

0.00

0.80

2.70

0.75

12.75

0.8mm

1.6mm

0.80mm

Dimensions are in millimeters

0.00

2.55

0.85

3.75

4.95

6.15

7.35

8.55

9.75

10.95

12.65

13.50

0.0

26.00

21.20

21.40

20.00

18.80

17.60

16.40

15.20

14.00

12.80

11. 60

10.40

9.20

8.00

6.80

5.60

4.40

3.20

2.00

3.25

4.65

6.05

7.45

8.85

10.25

20.70

Ground Pads

0.8 x 1.0 mm

Host Ground Plane Edge
(See Mounting Details)

(Top View)

RN52-DS

FIGURE 1-2: RECOMMENDED PCB FOOTPRINT

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Advanced Information

Figure 1-3 shows the pinout and Ta bl e 1- 4 describes

RN52

Top View

GND

GPIO7

GPIO6

PWREN

VDD

PCM_IN

PCM_OUT

PCM_SYNC

PCM_CLK

GND

GND
GPIO3
GPIO2
AICO0
GPIO4
GPIO5
GPIO12
GPIO13
GPIO11
GPIO10
GPIO9
USBD­USBD+
UART_RTS
UART_CTS
UART_TX
UART_RX

GND

SPKR_L+

SPKR_R+

SPKR_L-

SPKR_R-

AGND

MIC_R-

MIC_L-

MIC_R+

MIC_L+

MIC_BIAS

LED0
LED1

SPI_MOSI

SPI_SCK

SPI_MISO

SPI_SS

GND

GND

GND

GND

GND

GND

1
2
3
4
5
6
7
8

9
10
11
12
13
14
15
16
17

44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28

18

19202122232425

26

27

5049484746

45

the module’s pins.

FIGURE 1-3: PIN DIAGRAM

RN52-DS

TABLE 1-4: PIN DESCRIPTION (PART 1 OF 3) Note 1

Pin Symbol I/O Type Description Direction Default

1 GND Ground. Ground.
2 GPIO3 Bidirectional with program-

mable strength internal
pull-up/down.

3 GPIO2 Bidirectional with program-

4 AIO0 Bidirectional. Analog programmable input/output line. I/O
5 GPIO4 Bidirectional with program-

mable strength internal
pull-up/down.

mable strength internal
pull-up/down.

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This pin enters device firmware update (DFU)
mode at bootup if a USB device powers VBUS.
GPIO3 requires 47 kΩ to ground and 22 kΩ to
the USB VBUS signal if the USB VBUS is supply­ing power to the main board.

Reserved, event register. Toggles from high to
low for 100 ms to indicate that the module’s state
has changed. A microcontroller can enter com­mand mode and poll the state register using the
Q action command.

Factory reset mode. To reset the module to the
factory defaults, GPIO4 should be high on
power-up and then toggle low, high, low, high
with a 1 second wait between the transitions.

Advanced Information

Input Low

Output High

Input Low

RN52-DS

TABLE 1-4: PIN DESCRIPTION (PART 2 OF 3) Note 1

Pin Symbol I/O Type Description Direction Default

6 GPIO5 Bidirectional with program-

mable strength internal
pull-up/down.

7 GPIO12 Bidirectional with program-

mable strength internal
pull-up/down.

8 GPIO13 Bidirectional with program-

mable strength internal
pull-up/down.

9 GPIO11 Bidirectional with program-

mable strength internal
pull-up/down.

10 GPIO10 Bidirectional with program-

mable strength internal
pull-up/down.

11 GPIO9 Bidirectional with program-

mable strength internal
pull-up/down.

12 USBD- Bidirectional. USB data minus. I/O
13 USBD+ Bidirectional. USB data plus with selectable internal 1.5-Kohm

14 UART_RTS CMOS output, tri-state, with

weak internal pull-up.

15 UART_CTS CMOS input with weak

internal pull-down.

16 UART_TX CMOS output, tri-state, with

weak internal pull-up.

17 UART_RX CMOS input with weak

internal pull-down.

18 GND Ground. Ground.
19 GPIO7 Bidirectional with program-

mable strength internal
pull-up/down.

20 GPIO6 Bidirectional with program-

mable strength internal
pull-up/down.

21 PWREN Analog. Pull high to power up RN52.
22 VDD 3.3-V power input. 3.3v power input.
23 PCM_IN CMOS input, with weak

internal pull down.

24 PCM_OUT CMOS input, with weak

internal pull down.

25 PCM_SYNC Bidirectional with weak

internal pull down.

26 PCM_CLK CMOS input, with weak

internal pull down.

Programmable I/O. I/O High

Programmable I/O. I/O High

Programmable I/O. I/O High

Programmable I/O. I/O High

Programmable I/O. I/O High

When you drive this signal low, the module’s

Input High
UART goes into command mode. If this signal
floats high, the UART is in data mode. Reserved.
Not available for use at runtime.

I/O

pull-up resistor.

UART request to send active low. Output

UART clear to send active low. Input

UART data output. Output

UART data input. Input

Driving this pin low sets the UART baud rate to

I/O High
9,600. By default the pin is high with a baud rate
of 115,200.

Programmable I/O. I/O High

Synchronous data input, configurable for
SPDIF_IN or SD_IN (I

Synchronous data input, configurable for
SPDIF_OUT or SD_OUT (I

2

S).

2

S).

Input

Input

Synchronous data sync; WS (I2S). I/O

Synchronous data clock; SCK (I

2

S). Input

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Advanced Information

RN52-DS

TABLE 1-4: PIN DESCRIPTION (PART 3 OF 3) Note 1

Pin Symbol I/O Type Description Direction Default

27 GND Ground. Ground.
28 SPI_SS CMOS input with weak

internal pull-up.

29 SPI_MISO CMOS output, tri-state, with

weak internal pull-down.

30 SPI_CLK Input with weak internal

pull-down.

31 SPI_MOSI CMOS input, with weak

internal pull-down.

32 LED1 Open drain output. Drives an LED. For the RN-52-EK board, this

33 LED0 Open drain output. Drives an LED. For the RN-52-EK board, this

34 MIC_BIAS Analog. Microphone bias. Output
35 MIC_L+ Analog. Microphone input positive, left. Output
36 MIC_R+ Analog. Microphone input positive, right. Output
37 MIC_L- Analog. Microphone input negative, left. Output
38 MIC_R- Analog. Microphone input negative, right. Output
39 AGND Analog. Ground connection for audio.
40 SPK_R- Analog. Speaker output negative (right side). Output
41 SPK_L- Analog. Speaker output negative (left side). Output
42 SPK_R+ Analog. Speaker output positive (right side). Output
43 SPK_L+ Analog. Speaker output positive (left side). Output
44 GND Ground. Ground.
45 GND Ground. RF ground.
46 GND Ground. RF ground.
47 GND Ground. RF ground.
48 GND Ground. RF ground.
49 GND Ground. RF ground.
50 GND Ground. RF ground.

Note 1: All GPIO pins default to input with weak pull-down.

Chip select for Synchronous Serial Interface
active low.

Serial Peripheral Interface (SPI) output. Output

SPI clock. Input

SPI input. Input

signal drives the red LED.

signal drives the blue LED.

Input

Output

Output

1.1 Audio Interface Circuit Description

The RN52 audio interface circuit consists of:

• Stereo audio CODEC

• Dual audio inputs and dual outputs

• Configurable S/PDIF and I

The audio input circuitry has a dual audio input that can
be configured as single-ended or fully differential and
programmed for microphone or line input. It has an
analog and digital programmable gain stage so that it
can be optimized for different microphones. See

Figure 1-4.

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2

S interface

Advanced Information

1.1.1 STEREO AUDIO CODEC INTERFACE

The stereo audio CODEC interface has stereo and
mono analog input/output for voice and audio bands. It
supports the IEC-60958 stereo digital audio bus stan­dards, e.g., S/PDIF and AES3/EBU.

The built-in CODEC uses a fully differential architecture
in the analog signal path, which results in low noise
sensitivity and good power supply rejection while effec­tively doubling the signal amplitude. It operates from a

1.5 V single power supply and uses a minimum of

external components. See Figure 1-5.