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The communication between the UEM and the UPP is done on the bi-directional CBUS
and DBus. The CBUS is controlled by the MCU and can operate at a speed of maximum 1
MHz. The DBus is controlled by the DSP and can operate at a maximum speed of 13 MHz.
Both processors are located in the UPP.
The UEM is one of the two Asics in the baseband module.
UEM Startup/ Powerdown Sequence
The functional behavior of the UEM can be divided into 7 different states. Since the UEM
controls the regulated power distribution of the phone, each of these states affects the
general functionality of the phone:
• No supply
• Power off
• Power on
Because the Junction Board switches off the Engine Power supply (VEBpwr on junction
board, VBAT on the Engine Board) the UEM will be started by Poweron mode. During the
Power-Up Sequence the UEM detects that the Poweronx line is pushed to ground by the
Issue 2.0 Mar/2005
Copyright © 2005 Nokia Corporation.
TF4 Technical Information