Mbus Interface - Nokia RM-51 Service Manual

RM-51
Nokia Customer Care Baseband troubleshooting
Figure 92 Flash interface layout (FBUS/MBUS test pads layout)

MBUS interface

MBUS is a two-wire RX and TX interface between UPP_WD2 and UEMEK. From UEMEK the interface continues to
flash/test interface as one-wire interface. UEMEK 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 UEMEK can be tested with Phoenix (ST_MBUS_RX_TX_LOOP_TEST).
Flashing is not possible if there is a problem in MBUS. For the location of the MBUS signal in the test pads and
the pad layout, see figure .
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