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Version 3.3r 4/9/2012

7

RN -41 -DS

The following sections provide information on designing with the RN-41 module, including radio interference, factory reset,

solder reflow profile, connection status, etc.

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.