Can the customer design the application is such a way that they
can change from the internal sim card to the external and back to
the internal without turning off the GM862 modem?
The GM862 don`t permit that internal SIM and external SIM are simultaneously
A solution could be this one:
You must use two external SIM card Holder and add two three states buffers
to separate the not active SIM from the bus of active SIM.
On the GM862 there is a CCIO line for managing the inserting and removing of
the external SIM card Holder.
The CCIO pin must be managed from an external logic control in such a way
1- at the ignition of GM862 the SIM must be inserted and the CCIO pin must
2- when you need to change SIM you must switch the CCIO pin high
3- to set in tristate the buffer of SIM that you want disable.
4- to activate the buffer of the SIM you want to use
5- you must put the CCIO pin low again.
6- now the GM862 starts with the SIM inizialization again
Note: There is no limit about number of SIMs, obviously you have to use the
same number of SIM and three state buffers.