5. AVR AT90USB82/162 Memories
This section describes the different memories in the AT90USB82/162. The AVR architecture has
two main memory spaces, the Data Memory and the Program Memory space. In addition, the
AT90USB82/162 features an EEPROM Memory for data storage. All three memory spaces are
linear and regular.
5.1
In-System Reprogrammable Flash Program Memory
The AT90USB82/162 contains 8K / 16K 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 4K x 16, 8K 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 100,000 write/erase cycles. The
AT90USB82/162 Program Counter (PC) is 16 bits wide, thus addressing the 8K / 16K program
memory locations. The operation of Boot Program section and associated Boot Lock bits for
software protection are described in detail in “Memory Programming” on page 243. “Memory
Programming” on page 243 contains a detailed description on Flash data serial downloading
using the SPI pins or the debugWIRE 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 “Instruction Execution Tim-
ing” on page 12.
16
AT90USB82/162
7707D–AVR–07/08
ATMEL [ ATMEL ]
