
SIM card fault
The whole SIM interface is located in two chips: UPP_WD2 and UEMEK. UEMEK contains the SIM interface logic
level shifting. UPP_WD2 provides SIMClk through UEMEK to the SIM. The SIM interface supports both 3V and 1.8V
SIMs. There is an EMIF component (3 lines EMI filter) between the SIM card and the UEMEK which isn’t shown in
the figure below.
Figure 97 UPP_WD2 and UEMEK SIM connections (simplified)
The SIM power up/down sequence is generated in the UEMEK. This means that the UEMEK generates the RST
signal to the SIM. The card detection is taken from the BSI signal, which detects the removal of the battery. A
comparator inside the UEMEK monitors the BSI signal from the SimCardDet input. The threshold voltage is
calculated from the battery size specifications.
First, the SW attempts to power up the SIM with 1.8V. If this does not succeed, power up is repeated with VSIM
switched to 3V.
The data communication between the card and the phone is asynchronous half duplex. The clock supplied to
the card is in GSM system 1.083MHz or 3.25MHz. The data baud rate is SIM card clock frequency divided by 372
(by default), 64, 32, or 16.
RM-51
Nokia Customer Care
Baseband troubleshooting
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Company Confidential
9238460 (Issue 1)
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