User's Manual

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www.rovingnetworks.com Version 3.3r 10/3/2012 8
RN-41-DS
Reset Circuit
The RN-41 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 7. 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.
High The module is connected to another device over Bluetooth.
Table 8. 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.
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
• HCI over USB