Block Diagram - Nokia c2-00 Service Manual

RM-704
RF Troubleshooting
The Bluetooth device UART interface allows the device to communicate with the phone baseband engine
using Bluetooth HCI (Host Control Interface) commands. 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: SYS_CLK (26.0MHz) 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
SYS_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 times when
the Bluetooth device is in standby mode it is only necessary to provide a SLEEP_CLK signal. The Bluetooth ASIC
is powered directly from the phone battery voltage line (VBAT). An internal regulator is enabled when
Bluetooth is switched on.
Bluetooth audio signals are sent to and from the device using a PCM interface. The Bluetooth RF signal is
routed via a buried track to the Bluetooth antenna on the side of the PWB. An RF filter is needed between
the Bluetooth antenna and Bluetooth ASIC to prevent interference to and from the cellular phone antenna.

Block diagram

The following block diagram shows how Bluetooth is connected to the host engine.
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