Baseband Serial Interface Troubleshooting; Cbus - Nokia NHL-2NA Series Troubleshooting Instructions

CCS Technical Documentation

Baseband serial interface troubleshooting

CBUS

CBUS is a three wire serial interface between main baseband components. The bus con-
sists of data, clock and bus_enable signals. In NHL-2NA the bus is connected from UPP
WD2 to AEM, UEM and the BT module. UPP_WD2 takes care of controlling the traffic on
the bus.
If the interface is faulty from the UPP WD2's end the phone will not boot properly as
powering configurations do not work. Traffic on the bus can be monitored from three
pins on the BT module. Pins are shown below.
Issue 1 07/02
Figure 17:
CBUS measuring points
¤Nokia Corporation
CBusClk
CBusDa
CBusEnx
NHL-2NA
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