AT83EC5123 ATMEL Corporation, AT83EC5123 Datasheet - Page 156

• Manufacturer Part Number: AT83EC5123
• Description: (AT8xx512x) Smart Card Reader ICs
• Manufacturer: ATMEL Corporation

CRAM/ROM
Configuration
Case EA = 0
Case EA = 1
Rollover Function
Mapping
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AT8xC5122/23
The split of internal memory spaces depends on the product and is detailed below.
The instruction codes are fetched from external or internal program memory depending
on the logic state of microcontroller’s EA pin. Only valid for high pin count packages
(VQFP64).
After the reset, the program counter is initialised to 0000h and the code instructions are
fetched from external program memory.
The ROM contains the bootloader code. After reset sequence the program counter is
initialized to F800h and the bootloader is run. The bootloader downloads the application
into the CRAM. The sources to download the application from are in priority:
•
•
•
Note:
Once the application is running in the internal lower 32K memory space, it can roll over
in the external upper 32K memory space. A bit called ENBOOT and contained in
AUXR1 register enables to select this function. ENBOOT bit is set to 1 by the reset
function.
The program memory space is described in Figure 90.
an external 32K EEPROM attached to a synchronous serial interface
a host attached to a USB interface
a host attached to a RS232C interface
Since the ROM is mapped in the upper 32K of program memory, the bootloader is not
able to provide direct interrup services.
4202B–SCR–07/03