Functional Description
The SIM interface module provides an interface to an external Universal Integrated Circuit Card (UICC) containing the Universal Subscriber Identity Module (USIM) application. The corresponding software module implements the SIM terminal transport, Card Application Toolkit (CAT) and application layer. It has a software interface to access all required USIM functions.
Block Diagram
The block diagram of SIM Interface is illustrated in 图 51. A main clock gate disables the module clock during any module inactivity for a minimal dynamic power consumption. The SIM clock is derived from the module clock and base for the Elementary Time Unit (ETU) generation. SIM clock and ETU are tracked by counters.
A shift register in the I/O module deserializes/serializes the bit stream and calculates/checks the parity. Data bytes are served by/to a Byte Direct Memory Access (DMA). The overall transmission is managed by the control unit. Events are signaled via interrupts. The UICC presence is monitored by the presence observer module.
