Rainbow Electronics ATmega128L - Manual (Page 16)

16
ATmega128(L)
2467B–09/01
AVR ATmega128
Memories
This section describes the different memories in the ATmega128. The AVR architecture
has two main memory spaces, the Data Memory and the Program Memory space. In
addition, the ATmega128 features an EEPROM Memory for data storage. All three
memory spaces are linear and regular.
In-System
Reprogrammable Flash
Program Memory The ATmega128 contains 128K bytes On-chip In-System Reprogrammable Flash mem-
ory for program storage. Since all AVR instructions are 16 or 32 bits wide, the Flash is
organized as 64K x 16. 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 1,000 write/erase cycles. The
ATmega128 Program Counter (PC) is 16 bits wide, thus addressing the 64K program
memory locations. The operation of Boot Program section and associated Boot Lock
Bits for software protection are described in detail in
“Boot Loader Support – Read-
While-Write Self-Programming” on page 266. “Memory Programming” on page 279 con-
tains 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 and ELPM – Extended Load Program Memory
instruction description).
Timing diagrams for instruction fetch and execution are presented in “Instruction Execu-
tion Timing” on page 13.
Figure 8. Program Memory Map
$0000
$FFFF
Program Memory
Application Flash Section
Boot Flash Section