User's Manual
Table Of Contents
- Features:
- Applications:
- RN-41 Block Diagram:
- 1.0 Device Overview
- 2.0 Application Information
- 3.0 Regulatory Approval
- 4.0 Ordering Information
- 5.0 Document Revision History
www.rovingnetworks.com Version 3.43 5/21/13 page 6
RN41-DS
2.0 APPLICATION INFORMATION
The following sections provide information on design-
ing with the RN-41/RN-41N module, including radio
interference, factory reset, solder reflow profile, con-
nection status, etc.
2.1 Reset Circuit
The RN-41/RN-41N 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 insta-
bility on power up. Often a microcontroller or embed-
ded 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 currntly avail-
able, such as the MCP809 or MCP102/121.
2.2 Factory Reset Using GPIO4
It is recommended to 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.
2.3 Connection Status
GPIO5 is available to drive an LED, and it blinks at var-
ious speeds to indicate status (see Ta b l e 2 - 1 ). GPIO2
is an output that directly reflects the connection state as
shown in Table 2-2.
2.4 Using the SPI Bus to Upgrade the
Flash Memory
While not required, this bus is very useful for configur-
ing the Bluetooth modules’ advanced parameters. The
bus is required when upgrading the module’s firmware.
The typical application schematic shown in Figure 2-6
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.
2.5 Module Mounting Details
Figure 2-1 and Figure 2-2 show the recommended
PCB footprint for the RN-41 and RN-41N, respectively.
When laying out the carrier board for the RN-41 mod-
ule, the areas under the antenna and shielding connec-
tions should not have surface traces, ground planes, or
exposed vias.
Figure 2-3 and Figure 2-4 show the recommended
mounting details for the RN-41 and RN-41N, respec-
tively. For optimal radio performance, the RN-41 mod-
ule’s antenna end should protrude at least 31 mm
beyond any metal enclosure.
FIGURE 2-1: RN-41 RECOMMENDED
PCB FOOTPRINT
TABLE 2-1: 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 2-2: GPIO2 STATUS
GPIO2
Status
Description
High The module is connected to another device
over Bluetooth.
Low The module is not connected over Blue-
tooth.
Host PCB
Ground Plane
Edge
Shield Pads X4
0.8 mm x 1.3 mm
Do not locate vias
or signal traces
under Shield Pads
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