Nokia NEM-4 Series Troubleshooting Instructions page 29

CCS Technical Documentation
SIM card
The whole SIM interface locates in two chips UPP_WD2 and UEM. UEM contains the SIM
interface logic level shifting. UPP provides SIMClk through UEM to the SIM. SIM inter-
face supports both 3 V and 1.8 V SIMs.
UPP & UEM SIM connections
SIM
C5 C6 C7
C1 C2 C3
BSI line from battery
The SIM power up/down sequence is generated in the UEM. This means that the UEM
generates the RST signal to the SIM. Also the SIMCardDet signal is connected to UEM.
The card detection is taken from the BSI signal, which detects the removal of the battery.
Monitoring of the BSI signal is done by a comparator inside UEM. The threshold voltage
is calculated from the battery size specifications.
The SIM interface is powered up when the SIMCardDet signal indicates "card in". This
signal is derived from the BSI signal. SW tries first to power up the SIM with 1.8 V. If this
doesn't succeed power up is repeated with VSIM switched to 3 V.
The data communication between the card and the phone is asynchronous half duplex.
The clock supplied to the card is in GSM system 1.083 MHz or 3.25 MHz. The data
baudrate is SIM card clock frequency divided by 372 (by default), 64, 32 or 16.
Issue 1 09/2003
Company Confidential
GND
SIMDATA
SIMCLK
SIMRST
UEM
VSIM
SIMIF
register
BSI
Copyright  2003 Nokia Corporation
Company Confidential
SIMIO
SIMIO
SIMClk
SIMClk
Data
Data
UIF Block
UEMInt
UEM
digital
CBusDa
logic
CBusEnX
CBusClk
NEM-4
BB Troubleshooting
GND
UPP
Page 6(a)-27