RH-47
7 - Baseband Description & Troubleshooting
FBUS
FBUS is a two wire RX and TX interface between UPP and flash/test interface. The bus
goes through UEM which adjusts the voltage levels to suit UPP_WD2. The interface volt-
age level on the phone flash/test pad pattern is 2.78V and on the UPP WD2 end it is 1.8V.
The functionality of this interface should not affect the device boot into NORMAL, LOCAL
or TEST modes. Phoenix tests can be performed through MBUS interface in the case of a
failure in FBUS interface. Flashing is not possible, if there is a problem in FBUS.
MBUS
MBUS is a two wire RX and TX interface between UPP and UEM. From UEM the interface
continues to flash/test interface as a one wire interface. UEM also adjusts the voltage
levels. The interface voltage level on the phone flash/test pad pattern is 2.78V and on the
UPP WD2 end it is 1.8V. MBUS traffic between UPP WD2 and UEM can be tested with
Phoenix (ST_MBUS_RX_TX_LOOP_TEST). Flashing is not possible, if there is a problem in
MBUS.
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Company Confidential
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