[F A Q] Exernal SIM card holder

One thought on “[F A Q] Exernal SIM card holder

  1. Q:

    Can the customer design the application in
    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?

     

    A:

    The GM862 doesn’t permit that internal SIM and external SIM are simultaneously inserted.
    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 CCIN line for managing the
    inserting and removing of the external SIM card Holder.
    The CCIN pin must be managed from an external logic control in such a way that:

    • at the ignition of GM862 the SIM must be inserted and the CCIN pin must be low.
    • when you need to change SIM you must switch the CCIN pin high
    • to set in tristate the buffer of SIM that you want disable.
    • to activate the buffer of the SIM you want to use
    • you must put the CCIN pin low again.
    • now the GM862 starts with the SIM initialization again

    Note: There is no limit about number of SIMs, obviously you have to use the
    same number of SIM and three state buffers.