User's Manual

MC55/56 Hardware Interface Description
Confidential / Preliminary
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MC55/56_hd_v03.00 Page 59 of 104 16.08.2005
3.11.1 Requirements for using the CCIN pin
According to ISO/IEC 7816-3 the SIM interface must be immediately shut down once the SIM
card is removed during operation. Therefore, the signal at the CCIN pin must go low before
the SIM card contacts are mechanically detached from the SIM interface contacts. This shut-
down procedure is particularly required to protect the SIM card as well as the SIM interface
of MC55/56 from damage.
An appropriate SIM card detect switch is required on the card holder. For example, this is
true for the model supplied by Molex, which has been tested to operate with MC55/56 and is
part of the Siemens reference equipment submitted for type approval. Molex ordering
number is 91228-0001, see also Chapter 9.
The module’s startup procedure involves a SIM card initialisation performed within 1 second
after getting started. An important issue is whether the initialisation procedure ends up with a
high or low level of the CCIN signal:
a) If, during startup of MC55/56, the CCIN signal on the SIM interface is high, then the
status of the SIM card holder can be recognized each time the card is inserted or
ejected.
A low level of CCIN indicates that no SIM card tray is inserted into the holder. In this
case, the module keeps searching, at regular intervals, for the SIM card. Once the SIM
card tray with a SIM card is inserted, CCIN is taken high again.
b) If, during startup of MC55/56, the CCIN signal is low, the module will also attempt to
initialise the SIM card. In this case, the initialisation will only be successful when the
card is present.
If the SIM card initialisation has been done, but the card is no more operational or
removed, then the module will never search again for a SIM card and only emergency
calls can be made.
Removing and inserting the SIM card during operation requires the software to be
reinitialised. Therefore, after reinserting the SIM card it is necessary to restart MC55/56.
It is strongly recommended to connect the contacts of the SIM card detect switch to the CCIN
input and to the CCVCC output of the module as illustrated in the sample diagram in Figure
20.
Note: No guarantee can be given, nor any liability accepted, if loss of data is encountered
after removing the SIM card during operation.
Also, no guarantee can be given for properly initialising any SIM card that the user
inserts after having removed a SIM card during operation. In this case, the application
must restart MC55/56.