RN41/RN41N
DS50002280C-page 10
2014-2022 Microchip Technology Inc.
FIGURE 2-5:
RN41 HOST PCB EXAMPLE LAYOUT
2.5
External Antenna Types (RN41N)
The RN41N module’s antenna pin (pin 25) provides a
50-ohm impedance to external antennas. Pin 25 can
connect directly to a coaxial cable or to an antenna
connector such as a U.FL or reverse polarity SMA.
The PCB trace from pin 25 to the coaxial cable or con-
nector should be less than 0.2 inches (5 mm) for mini-
mum loss and the best impedance match. If the PCB
trace is longer, it should be a 50-ohm impedance
microstrip trace. Connect adjacent ground pins 24 and
26 to a low-impedance ground on the host PCB and the
antenna connection.
gives example host
PCB layout to a U.FL connector.
Modular certification of the RN41N module was per-
formed with the external antenna types listed in the fol-
lowing table. Refer to
for specific regulatory requirements by
country.
2.6
HCI Mode
Microchip 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 base-
band. The HCI provides a command reference inter-
face 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.
In this mode, the Bluetooth stack is no longer on-board
the module. It is offloaded to the interfacing host pro-
cessor. The Bluetooth module is used as a radio, per-
forming the lower level MAC functionalities, while the
application stack runs on the host processor.
Using the module in HCI mode enables designers to
implement profiles that are not natively supported on
the Bluetooth module.
No Copper
In these Areas
RN-41
Okay
RN-41
Best
RN-41
Okay
RN-41
Okay
TABLE 2-3:
TESTED EXTERNAL
ANTENNA TYPES
Type
Gain (dBi)
Monopole
0.56
Whip
8
Yagi
15
Note:
HCI mode is only available by ordering
part RN41HCI for UART interface; or
RN41U for USB interface.
Summary of Contents for RN41
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