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RN42/RN42N Class 2 Bluetooth Module
Features
• Fully qualified Bluetooth® version 2.1 module,
supports version 2.1 + Enhanced Data Rate (EDR)
• Backwards-compatible with Bluetooth version 2.0,
1.2, and 1.1
• Postage stamp sized form factor, 13.4 mm x
25.8 mm x 2 mm (RN42) and 13.4 mm x 20 mm x
2 mm (RN42N)
• Low power (26 uA sleep, 3 mA connected, 30 mA
transmit)
• UART (SPP or HCI) and USB (HCI only) data
connection interfaces.
• Sustained SPP data rates: 240 Kbps (slave), 300
Kbps (master)
• HCI data rates: 1.5 Mbps sustained, 3.0 Mbps
burst in HCI mode
• Embedded Bluetooth stack profiles included
(requires no host stack): GAP, SDP, RFCOMM, and
L2CAP protocols, with SPP and DUN profile
support
• Bluetooth SIG certified
• Castellated SMT pads for easy and reliable PCB
mounting
• Certifications: FCC, ICS, CE
• Environmentally friendly, RoHS compliant
Applications
• Cable replacement
• Barcode scanners/readers
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• Measurement and monitoring systems
• Industrial sensors and controls
• Medical devices
• Computer accessories
Description
The RN42 is a small form factor, low power, class 2
Bluetooth radio for designer’s who want to add wireless
capability to their products. The RN42 supports multiple
interface protocols, is simple to design in, and is fully
certified, making it a complete embedded Bluetooth
solution. The RN42 is functionally compatible with the
RN 41. With its high-performance, on-chip antenna and
support for Bluetooth EDR, the RN42 delivers up to a 3
Mbps data rate for distances up to 20 meters.
The RN42 is also available in a package without an
antenna (RN42N). Useful when the application requires
an external antenna, the RN42N is shorter in length and
has RF pads to route the antenna signal.
Figure 1. RN42 Block Diagram
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RF
Switch BALUN
CSR BlueCore-04
External
Crystal
Flash Memory
VCC
GND
GPIO4
GPIO5
GPIO6
USB
UART
PCM
RN42
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OVERVIEW
• Baud rate speeds: 1,200 bps up to 921 Kbps, non-standard baud rates can be programmed
• Class 2 radio, 60 feet (20 meters) distance, 4 dBm output transmitter, -80 dBm typical receive sensitivity
• Frequency 2,402 ~ 2,480 MHz
• FHSS/GFSK modulation, 79 channels at 1-MHz intervals
• Secure communications, 128-bit encryption
• Error correction for guaranteed packet delivery
• Configuration via the local UART and over-the-air RF
• Auto-discovery/pairing does not require software configuration (instant cable replacement)
• Auto-connect master, I/O pin (DTR), and character-based trigger modes
The module’s moisture sensitivity level (MSL) is 1. Table 1 shows the module’s size and weight.
Table 1. Module Size & Weight
Parameter
RN42
RN42N
Units
Size
13.4 x 25.8 x 2
19 x 13.4 x 2
mm
Weight
0.045
0.040
Oz.
Tables 2 through 6 provide detailed specifications for the module.
Table 2. Environmental Conditions
Parameter
Value
Temperature Range (Operating)
-40o C ~ 85o C
Temperature Range (Storage)
-40o C ~ 85o C
Relative Humidity (Operating)
≤ 90%
Relative Humidity (Storage)
≤ 90%
Table 3. Digital I/O Characteristics
3.0 V ≤ VDD ≤ 3.3 V
Min.
Typ.
Max.
Units
Input Logic Level Low
-0.4
-
+0.8
V
Input Logic Level High
0.7 VDD
-
VDD + 0.4
V
Output Logic Level Low
-
-
0.2
V
Output Logic Level High
VDD - 0.2
-
-
V
All I/O pins (Except reset) Default to Weak Pull Down
+0.2
+1.0
+5.0
uA
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Table 4. Electrical Characteristics
Parameter
Min.
Typ.
Max.
Units
Supply voltage (DC)
3.0
3.3
3.6
V
Average Power Consumption
Radio ON (discovery or inquiry window time), Note (1)
40
mA
Connected Idle (no sniff)
25
mA
Connected Idle (sniff 100 ms)
12
mA
Connected with data transfer
40
45
50
mA
Deep sleep idle mode
26
uA
Notes:
1. If, in slave mode, there are bursts of radio ON time that vary with the windows. Depending on how you set the windows, that
determines your average current.
Table 5. Radio Characteristics
Parameter
Freq.
(GHz)
Min.
Typ.
Max.
Bluetooth
Specification
Units
Sensitivity at 0.1% BER
2.402
-
-80
-86
≤ -70
dBm
2.441
-
-80
-86
dBm
2.480
-
-80
-86
dBm
RF Transmit Power
2.402
0
2
4
≤ 4
dBm
2.441
0
2
4
dBm
2.480
0
2
4
dBm
Initial Carrier Frequency Tolerance
2.402
-
5
75
75
kHz
2.441
-
5
75
kHz
2.480
-
5
75
kHz
20dB bandwidth for modulated carrier
-
900
1,000
≤ 1000
kHz
Drift (Five slots packet)
-
15
-
40
kHz
Drift Rate
-
13
-
20
kHz
∆f1avg Max Modulation
2.402
140
165
175
> 140
kHz
2.441
140
165
175
kHz
2.480
140
165
175
kHz
∆f2avg Min Modulation
2.402
140
190
-
115
kHz
2.441
140
190
-
kHz
2.480
140
190
-
kHz
Table 6. Range Characteristics (Approximate Range In Office Environment)
Range
RN42
After One Wall
55 feet
After Two Walls
60 feet
After Three Walls
36 feet
The readings shown in Table 6 are approximate and may vary depending upon the RF environment. Bluetooth hops in a
pseudo-random fashion over the 79 frequencies in the ISM band to adapt to the interference. Data throughput and range
vary depending on the RF interference environment.
Figure 2 shows the module’s pinout and Table 7 describes the pins.
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Figure 2. RN42/RN42N Pinout
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Table 7. Pin Description
Pin
Name
Description
Default
Voltage
(V)
1
GND
Ground
0
2
SPI_MOSI
Programming only
No Connect
3
3
GPIO6
Set BT master (high = auto-master mode)
Input to RN42 with weak pulldown
0 - 3.3
4
GPIO7
Set Baud rate (high = force 9,600, low = 115 K or
firmware setting)
Input to RN42 with weak pulldown
0 - 3.3
5
RESET
Active-low reset. Hold low for low-power
operation.
Input to RN42 with 1K pullup
6
SPI_CLK
Programming only
No Connect
7
PCM_CLK
PCM interface
No Connect
8
PCM_SYNC
PCM interface
No Connect
9
PCM_IN
PCM interface
No Connect
10
PCM_OUT
PCM interface
No Connect
11
VDD
3.3-V regulated power input
12
GND
Ground
13
UART_RX
UART receive Input
Input to RN42
0 - 3.3
14
UART_TX
UART transmit output
High level output from RN42
0 - 3.3
15
UART_RTS
UART RTS, goes high to disable host transmitter
Low level output from RN42
0 - 3.3
16
UART_CTS
UART CTS, if set high, disables transmitter
Low level input to RN42
0 - 3.3
17
USB_D+
USB port
Pull up 1.5 K when active
0 - 3.3
18
USB_D-
USB port
0 - 3.3
GND
SPI_MOSI
GPIO6
GPIO7
RESET
SPI_CLOCK
PCM_CLK
PCM_SYNC
PCM_IN
PCM_OUT
VDD
GND
SPI_MISO
SPI_CSB
GPIO4
GPIO5
GPIO3
GPIO2
USB_D-
USB_D+
UART_CTS
UART_RTS
UART_TX
UART_RX
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
AIO1
GND
GPIO11
GPIO10
GPIO9
GPIO8
GND
AIO0
35 29 34 33 32 31 28 30
RN42
Top View
GND
SPI_MOSI
GPIO6
GPIO7
RESET
SPI_CLOCK
PCM_CLK
PCM_SYNC
PCM_IN
PCM_OUT
VDD
GND
SPI_MISO
SPI_CSB
GPIO4
GPIO5
GPIO3
GPIO2
USB_D-
USB_D+
UART_CTS
UART_RTS
UART_TX
UART_RX
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
AIO1
GND
GPIO11
GPIO10
GPIO9
GPIO8
GND
AIO0
35 29 34 33 32 31 28 30
RN42N
Top View
GND
RFPAD
GND
27 26 25
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Pin
Name
Description
Default
Voltage
(V)
19
GPIO2
Status, high when connected, low otherwise
Output from RN42
0 - 3.3
20
GPIO3
Auto discovery = high
Input to RN42 with weak pulldown
0 - 3.3
21
GPIO5
Status, toggles based on state, low on connect
Output from RN42
0 - 3.3
22
GPIO4
Set factory defaults
Input to RN42 with weak pulldown
0 - 3.3
23
SPI_CSB
Programming only
No Connect
24
SPI_MISO
Programming only
No Connect
25
GND
Ground for RN42N
26
RF Pad
RF pad for RN42N
27-
29
GND
Ground for RN42N
30
AIO0
Optional analog input
Not Used
31
GPIO8
Status (RF data Rx/Tx)
Output from RN42
0 - 3.3
32
GPIO9
I/O
Input to RN42 with weak pulldown
0 - 3.3
33
GPIO10
I/O (remote DTR signal)
Input to RN42 with weak pulldown
0 - 3.3
34
GPIO11
I/O (remote RTS signal)
Input to RN42 with weak pulldown
0 - 3.3
35
AIO1
Optional analog input
Not Used
Figure 3 shows the module’s physical dimensions.
Figure 3. RN42/RN42N Physical Dimensions
All Dimensions Are In mm
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TYPICAL APPLICATION SCHEMATIC
Figure 4 shows a typical application schematic. Because the RN41 and RN42 are functionally compatible, this diagram
applies to both modules.
Figure 4. Application Schematic
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DESIGN CONCERNS!
The following sections provide information on designing with the RN42 module, including radio interference, factory reset,
solder reflow profile, connection status, etc.
Reset Circuit
The RN42 contains a 1k pullup to VCC, and the reset polarity is active low. The module’s reset pin has an optional power-
on-reset circuit with a delay, which should only be required if the input power supply has a very slow ramp or tends to
bounce or have instability on power up. Often a microcontroller or embedded CPU I/O is available to generate the reset
once power is stable. If not, designers can use one of the many low-cost power supervisor chips currently available, such
as the MCP809, MCP102/121, and Torex XC61F.
Factory Reset Using GPIO4
Roving Networks recommends that designers connect the GPIO4 pin to a switch, jumper, or resistor so it can be accessed.
This pin can be used to reset the module to its factory default settings, which is critical in situations where the module has
been misconfigured. 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.
Connection Status
GPIO5 is available to drive an LED, and it blinks at various speeds to indicate status (see Table 7). GPIO2 is an output that
directly reflects the connection state as shown in Table 8.
Table 8. GPIO5 Status
GPIO5 Status
Description
Toggle at 1 Hz
The module is discoverable and waiting for a connection.
Toggle at 10 Hz
The module is in command mode.
Low
The module is connected to another device over Bluetooth.
Table 9. GPIO2 Status
GPIO2 Status
Description
High
The module is connected to another device over Bluetooth.
Low
The module is not connected over Bluetooth.
HCI Mode
Roving Networks offers the Host Controller Interface (HCI) mode in addition to the standard operational mode of its
Bluetooth modules (standard mode refers to the on-board stack running on the module).
In HCI mode, the on-board stack is bypassed and the module is put in a state that runs the Bluetooth baseband. The HCI
provides a command reference interface to the baseband controller and the link manager, and provides access to the
hardware status and control registers. This interface provides a uniform method for accessing the Bluetooth baseband
capabilities.
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In this mode, the Bluetooth stack is no longer on-board the module. It is offloaded to the interfacing host processor. The
Bluetooth module is used as a radio, performing the lower level MAC functionalities, while the application stack runs on the
host processor.
Using the module in HCI mode allows designers to implement profiles that are not natively supported on the Bluetooth
module.
NOTE: HCI mode requires a separate firmware build that must be loaded into the module’s flash at the factory. Is not
upgradeable in the field.
Roving Networks offers HCI mode in two hardware interfaces:
• HCI over UART (RN42HCI-I/RM)
• HCI over USB (RN42U-I/RM)
HCI over UART
In this mode, the hardware interface between the host processor and the Bluetooth module is the UART. You must
interface the flow control signals between the host processor and the Bluetooth module for the HCI interface to work.
Failure to do so can cause the host processor and the Bluetooth module to become out of sync and break the Bluetooth
link.
HCI over USB
In this mode, the hardware interface between the host processor and the Bluetooth module is the USB. In this
architecture, the Bluetooth module is the USB slave and the host processor is the USB host.
Using the USB interface offers the advantage of a faster data link between the Bluetooth module and the host processor.
With this architecture, it is possible to achieve Bluetooth’s theoretical maximum throughput of 3 Mpbs.
Low Power
To achieve low-power operation, hold the module’s RESET pin low. With RESET = 0 VDC, the module consumes 35 uA of
power. If RESET is left floating or high, the module consumes 3 mA in sleep mode. To obtain the lowest power, the RN42
should be passive (in slave mode and not trying to make connections).
Using the SPI Bus to Upgrade the Flash Memory
While not required, this bus is very useful for configuring the Bluetooth modules’ advanced parameters. The bus is
required when upgrading the module’s firmware. The typical application schematic shown in Figure 4 shows a 6-pin
header that can be implemented to gain access to this bus. A minimum-mode version might simply use the SPI signals (4
pins) and obtain ground and VCC from elsewhere in the design.
Minimizing Radio Interference
When laying out the carrier board for the RN42 module, the areas under the antenna and shielding connections should not
have surface traces, ground planes, or exposed vias (see Figure 5). For optimal radio performance, the RN42 module’s
antenna end should protrude at least 5 mm beyond any metal enclosure.
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Figure 5. Minimizing Radio Interference
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Because the RN42N does not contain an antenna, it does not carry regulatory approvals.
If designers use Roving Networks recommended design, they can file for a permissible antenna change and use Roving
Networks’ regulatory approvals. The recommended antenna design for the RN42 is a PCB trace antenna. To meet the
regulatory compliance information, customers must use the trace pattern shown in Figure 6.
Figure 6. Antenna Trace Pattern
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If designers choose to use another antenna, they must go through the regulatory approval process.
Do not located any surface
parts, surface traces, internal
traces, or ground planes under
the antenna area.
25.6 mm
Top View
1.5 mm
13.4 mm
1.5 mm
7.0 mm
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
10
19
18
17
16
15
14
13
35
29
34
33
32
31
28
30
Do not locate vias
or surface traces
under shield
connectors
(1.5 mm square).
1.5 mm
1.5 mm
80 mil
140 mil
40 mil
40 mil
Ground
Plane
Limit
Trace Width Is 20 mil
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Antenna Design
The pattern from the RF_OUT terminal pad should be designed with 50 ohms impedance and traced with straight lines
(see Figure 7). The RF_OUT signal line should not run under or near the RN21 module. The GND plane should be on the
side of the PCB to which the module is mounted. GND should be reinforced with through-hole connections and other
means to stabilize the electric potential.
Figure 7. Antenna Design
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Solder Reflow Profile
The lead-free solder reflow temperature and times are:
• Temperature—230° C, 30 - 40 seconds, peak 250° C maximum
• Preheat temperature—165° ± 15° C, 90 to 120 seconds
• Time—Single pass, one time
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GND
GND
RF_OUT
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COMPLIANCE INFORMATION
Table 10 describes the module’s compliance information.
Table 10. Compliance Information
Category
Country
Standard
Radio
USA
FCC Part 15 Subpart B: 2008 Class B
FCC CRF Title 47 Part 15 Subpart C
FCC ID:
T9J-RN42
Europe
ETSI EN 301 489-1 V1.8.1
ETSI EN 301 489-17 V2.1.1
ETSI EN 300 328 V1.7.1
Canada
IC RSS-210 low power comm. device
Certification Number:
6514A-RN42
EMC
USA
FCC CFR47 Part 15 subclass B
Europe
EN 55022 Class B radiated
EN61000-4-2 ESD immunity
EN61000-4-3 radiated field
EN61000-4-6 RF immunity
EN61000-4-8 power magnetic immunity
Bluetooth
BQB LISTED
B014867- SPP and DUN profiles
Environmental
RoHS
RoHS compliant
ORDERING INFORMATION
Table 11 provides ordering information.
Table 11. Ordering Information
Part Number
Description
RN42-I/RM
Standard application firmware (SPP/DUN master and slave).
RN42HCI-I/RM
HCI firmware (HCI over H4 UART).
RN42U-I/RM
USB firmware (HCI over USB port).
RN42N-I/RM
Standard application firmware (SPP/DUN master and slave) without antenna.
For other configurations, contact Roving Networks directly.
Go to http://www.rovingnetworks.com for current pricing and a list of distributors carrying Roving Networks products.
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REVISION HISTORY
Version 2.32r 4/11/2013
• Updated the module part numbers.
Version 2.31r 10/15/2012
• Updated the GPIO5 status table to correctly show that when GPIO5 is low, it indicates that the module is
connected to another device over Bluetooth.
• Added information on pins 28 and 29 to the pinout table.
Roving Networks, Inc.
102 Cooper Court
Los Gatos, CA 95032
+1 (408) 395-5300
www.rovingnetworks.com
Copyright © 2012 Roving Networks. All rights reserved. Roving Networks is a
registered trademark of Roving Networks. Apple Inc., iPhone, iPad, iTunes, Made
for iPhone are registered trademarks of Apple Computer.
Roving Networks reserves the right to make corrections, modifications, and other
changes to its products, documentation and services at any time. Customers
should obtain the latest relevant information before placing orders and should verify
that such information is current and complete.
Roving Networks assumes no liability for applications assistance or customer’s
product design. Customers are responsible for their products and applications
which use Roving Networks components. To minimize customer product risks,
customers should provide adequate design and operating safeguards.
Roving Networks products are not authorized for use in safety-critical applications
(such as life support) where a failure of the Roving Networks product would
reasonably be expected to cause severe personal injury or death, unless officers of
the parties have executed an agreement specifically governing such use.
Roving Networks, Inc.
102 Cooper Court
Los Gatos, CA 95032
+1 (408) 395-5300
www.rovingnetworks.com
Copyright © 2013 Roving Networks. All rights reserved. Roving Networks is a
registered trademark of Roving Networks. Apple Inc., iPhone, iPad, iTunes, Made
for iPhone are registered trademarks of Apple Computer.
Roving Networks reserves the right to make corrections, modifications, and other
changes to its products, documentation and services at any time. Customers
should obtain the latest relevant information before placing orders and should verify
that such information is current and complete.
Roving Networks assumes no liability for applications assistance or customer’s
product design. Customers are responsible for their products and applications
which use Roving Networks components. To minimize customer product risks,
customers should provide adequate design and operating safeguards.
Roving Networks products are not authorized for use in safety-critical applications
(such as life support) where a failure of the Roving Networks product would
reasonably be expected to cause severe personal injury or death, unless officers of
the parties have executed an agreement specifically governing such use.
