User's Manual

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User Manual 2012/06/28
protect SIM access of the 6 pin connector. This must be performed every time when the SIM card holder
is accessed by the end user.
 If it is necessary to use long SIM bus lines of over 100mm, it is recommended to adopt serial resistors to
avoid electrical overshoot on SIM bus signals. Use 56 Ω for the clock line and 10Ω for the reset and data
lines.
 To use external SIM detection function, a GPIO pad must be connected to SIM holder.
Figure 4: SIM schematic with protection serial resistors & EXT_SIM_DET signal
The schematic above includes a hardware SIM card presence detector. When SIM card is not inserted into SIM
holder, Pin9 and Pin10 of SIM holder are disconnected. A GPIO detects a high level during boot. Then there is
no initialization to SIM card. When SIM card is inserted, Pin9 is short to Pin10 by mechanic contact, and a GPIO
detects a low level during boot.
 A 22pF capacitor is recommended on EXT_SIM_DET.
 SIM card must not be removed from its holder while it is still powered. Switch the module off properly with
the AT command, then remove the SIM card from its holder.
3.2.3 SIM CARD priority
The SIM card selection is performed thanks to KSIMSEL parameter.
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shall be configured to support to one of the following configuration:
- KSIMSEL=0  external SIM only
- KSIMSEL=1  internal SIM only
- KSIMSEL=2  priority to external SIM if both SIM cards are presents
 Change of KSIMSEL value is taken into account only after reboot
 Use of EXT_SIM_DET is mandatory to support KSIMSEL=2 feature (see KSIMSEL description in
reference [2])