User Guide

Clocking scheme

Figure 51 Clocking scheme

HW 53 engine clocks

RFCLK 38.4 MHz

SleepClk 32.768kHz

RFCLKEXT 38.4 MHz

SYSCLK 19.2 MHz

Bluetooth and FM RDS radio module

Bluetooth and FM radio receiver are provided by the same ASIC (Broadcom BCM2048). The device supports

Bluetooth operation and FM radio rececption in both European/USA and Japanese bands (the appropriate

region-specific FM radio band is pre-configured in the phone software). The UART interface allows the device

to communicate with the phone baseband engine using Bluetooth HCI commands. Commands to the FM radio

can also be sent over the I2C interface.

When Bluetooth is switched on, the phone user interface the BT_RESETX line is toggled to reset the Bluetooth

device, and commands are sent over the UART interface to configure the device. If UART communication fails

(due to a hardware fault) it will not be possible to switch on Bluetooth from the phone user interface.

The device has two clock signals: CWS_CLK (38.4 MHz) and SLEEP_CLK (32.768kHz). The SLEEP_CLK is supplied

all the time the phone is switched on. To maximise the phone standby time, it is only necessary to provide

a CWS_CLK signal when Bluetooth activity occurs, such as sending Bluetooth data to another device, or

checking periodically if there are any other Bluetooth devices attempting to communicate with it. At other

RM-348; RM-349; RM-350

System Module and User Interface

Issue 2 COMPANY CONFIDENTIAL Page 8 –9