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42073A-MCU Wireless-02/13
ATmega2564/1284/644RFR2
8 AVR Memories
This section describes the different memories in the ATmega2564/1284/644RFR2. The
AVR architecture has two main memory spaces, the Data Memory and the Program
Memory space. In addition, the ATmega2564/1284/644RFR2 features an EEPROM
Memory for data storage. All three memory spaces are linear and regular.
8.1 In-System Reprogrammable Flash Program Memory
The ATmega2564/1284/644RFR2 contains FLASH_SIZE Bytes On-chip In-System
AVR instructions are 16 or 32 bits wide, the Flash is 16 bit wide. For software security,
the Flash Program memory space is divided into two sections, Boot Program section
and Application Program section.
The Flash memory has an endurance of at least 2000 write/erase cycles. The
ATmega2564/1284/644RFR2 Program Counter (PC) is 16 bits wide, thus addressing
the required program memory locations. The operation of Boot Program section and
associated Boot Lock bits for software protection are described in detail in
"Boot Loaderon page 502 contains a detailed description on Flash data serial downloading using the
SPI pins or the JTAG interface.
Constant tables can be allocated within the entire program memory address space (see
the LPM – Load Program Memory instruction description and ELPM – Extended Load
Program Memory instruction description).
Timing diagrams for instruction fetch and execution are presented in
"InstructionFigure 8-6. Program Flash Memory Map
Boot Flash Section
Program Memory
Application Flash Section
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The application section of the Flash memory contains 3 user signature pages. These
pages can be used to store data that should never be modified by an application
program e.g. ID numbers, calibration data etc. For details see section
"User Signature8.2 SRAM Data Memory
organized. The ATmega2564/1284/644RFR2 is a complex microcontroller with more
peripheral units than can be supported within the 64 location reserved in the Opcode for