Baseband Serial Interface Troubleshooting; Cbus Interface - Nokia 6260 RM-25 Service Manual

RM-25
Baseband troubleshooting Nokia Customer Care

Baseband serial interface troubleshooting

CBUS interface

CBUS is a three-wire serial interface between the main baseband components.
The bus consists of data, clock and bus_enable signals. The bus is connected between UPP_WD2, UEME and ZOCUS.
UPP_WD2 takes care of controlling the traffic on the bus.
If the interface is faulty from the UPP_WD2's end, the phone does not boot properly as powering configurations
do not work.
Traffic on the bus can be monitored at the following test point and pins.
• R640 (test point J193 side)
• CBusEN1X J378 Pad
• CBusDA J377 Pad
The pads and pins are shown in the figures below.
CBUS test points
Figure 80 CBusClk test point
9235618 (Issue 2) Company Confidential Page 6–11
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