Fbus; Mbus - Nokia NHL-2NA Series Troubleshooting Instructions

CCS Technical Documentation

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
nor 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 interface.

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 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 PHOE-
NIX (ST_MBUS_RX_TX_LOOP_TEST). Flashing is not possible if there is a problem in
MBUS.
Issue 1 07/02 ¤Nokia Corporation
NHL-2NA
Page 49