Usim Controller Interface; Overview - Intel PXA27 Series Design Manual

USIM Controller Interface

This chapter describes the universal subscriber identity module (USIM) of Intel
Processor Family (PXA27x processor) controller interface guidelines.
19.1

Overview

The USIM controller is an interface for a GSM mobile handset. The USIM interface supports
communication with smart cards as specified in ISO standard 7816-3 and technical specification
3G TS 31.101 of the 3rd Generation Partnership Project.
Smart cards are used in many applications and the GSM network USIM card is only one of many
applications. Smart cards usually consist of a CPU, flash memory, and a serial-communication
interface device similar to the one described in this chapter. More sophisticated cards contain a
PLL for frequency enhancement. Encryption accelerators also exists in a smart card since many of
their applications are security oriented. In all smart card applications, the physical layer and data
link layer are identical, so this module can serve both layers as well.
The USIM interface is composed of eight major components:
•
Registers
•
Card interface
•
Receiver first in/first out (FIFO)
•
Transmitter FIFO
•
Receiver
•
Transmitter
•
Clock generator
•
Baud-rate generator
The transmitter converts the byte stored in its FIFO to serial output as specified by the standard.
The receiver performs the reverse action and stores the data in the Receiver FIFO. FIFOs holds up
to 16 bytes. The receiver FIFO also holds a parity-error indicator for each byte.
Transforming byte convention (inverse to direct and vice-versa) is performed when the byte exits
the FIFOs, that is, FIFO output is either inverted or left as is, according to the session convention.
In this manner, the program does not have to perform format inversion before character receipt.
Receiver, transmitter, and baud-rate generator blocks are clocked by an internal clock generated in
the clock generator. This unit also generates the card clock. Both receiver and transmitter baud
rates are controlled by the baud-rate generator. Software controls the session with the card by
updating the USIM registers. All signals going to the USIM card are processed in the Card-
Interface block as shown in
Intel® PXA27x Processor Family Design Guide
Figure 19-1.
19
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PXA27x
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