User's Manual

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www.rovingnetworks.com Version 3.3r 10/3/2012 9
RN-41-DS
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.
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 RN-41 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 RN-41 module’s antenna end should protrude at least 5 mm beyond any metal enclosure.
Figure 5. Minimizing Radio Interference
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Because the RN-41-N does not contain an antenna, it does not carry regulatory approvals.