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DEVELOPING A USB SMARTCARD READER WITH ST7SCR

3 ISO 7816 UART LIBRARY (CRD)

3.1 GENERAL INTRODUCTION

The aim of this library is to provide the user with a set of functions for using the Smartcard In-

terface (ISO7816-3 UART Interface) to directly access the hardware and to communicate with

an Integrated Circuit Card (ICC) through a few simple functions. This library is composed of 4

files:

– crd.c

– crd.h

– int_crd.c

– int_crd.h

The crd.x files provide the general functions for the main loop program. The int_crd.x files are

used for interrupt management.

The transactions between the ST7 microcontroller and the ICC are performed by the ICC_xxx

functions. These functions poll flags waiting for the end of the transaction. The transaction it-

self and the flag settings are managed by interrupts.

3.2 SMARTCARD INTERFACE FUNCTIONS

The Smartcard Interface (CRD) functions described below are very low level functions used to

interact directly with the hardware.

s

void CRD_Init(void)

This function resets and initialize the CRD and the local software flags.

s

unsigned char CRD_GetHwError(unsigned char * pHwErrorCode)

This function checks the hardware state and returns one of the following error codes:

– Slot_No_Error

– SlotError_HW_Error

– SlotError_ICC_Mute (no card present)

If the function returns SlotError_HW_Error, pHwErrorCode will contain one of the following

error codes:

– HardwareErrorCode_OverCurrent

– HardwareErrorCode_VoltageError

– HardwareErrorCode_OverCurrent_IT

– HardwareErrorCode_VoltageError_IT

Note: In case of a hardware error, the slot is inactivated (VCC Card off).