ATmega16U4 datasheet(19/408 Pages) ATMEL

19 / 408 page

7766D–AVR–01/09

ATmega16U4/ATmega32U4

“Memory Programming” on page 348 contains a detailed description on Flash data serial down-

loading 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 “Instruction Execution Tim-

ing” on page 14.

Figure 5-1.

Program Memory Map

5.2

SRAM Data Memory

Figure 5-2 shows how the ATmega16U4/ATmega32U4 SRAM Memory is organized.

The ATmega16U4/ATmega32U4 is a complex microcontroller with more peripheral units than

can be supported within the 64 location reserved in the Opcode for the IN and OUT instructions.

For the Extended I/O space from $060 - $0FF in SRAM, only the ST/STS/STD and LD/LDS/LDD

instructions can be used.

The first 2,816 Data Memory locations address both the Register File, the I/O Memory,

Extended I/O Memory, and the internal data SRAM. The first 32 locations address the Register

file, the next 64 location the standard I/O Memory, then 160 locations of Extended I/O memory

and the next 2,560 locations address the internal data SRAM.

The five different addressing modes for the data memory cover: Direct, Indirect with Displace-

ment, Indirect, Indirect with Pre-decrement, and Indirect with Post-increment. In the Register file,

registers R26 to R31 feature the indirect addressing pointer registers.

The direct addressing reaches the entire data space.

0x00000

Program Memory

Application Flash Section

Boot Flash Section

0x7FFF (32KBytes)

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