ATMEGA2561V ATMEL [ATMEL Corporation], ATMEGA2561V Datasheet - Page 25

• Manufacturer Part Number: ATMEGA2561V
• Description: 8-bit Microcontroller with 64K/128K/256K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

I/O Memory
General Purpose I/O Registers The ATmega640/1280/1281/2560/2561 contains three General Purpose I/O Registers.
2549K–AVR–01/07
The I/O space definition of the ATmega640/1280/1281/2560/2561 is shown in “Register
Summary” on page 416.
All ATmega640/1280/1281/2560/2561 I/Os and peripherals are placed in the I/O space.
All I/O locations may be accessed by the LD/LDS/LDD and ST/STS/STD instructions,
transferring data between the 32 general purpose working registers and the I/O space.
I/O Registers within the address range 0x00 - 0x1F are directly bit-accessible using the
SBI and CBI instructions. In these registers, the value of single bits can be checked by
using the SBIS and SBIC instructions. Refer to the instruction set section for more
details. When using the I/O specific commands IN and OUT, the I/O addresses 0x00 -
0x3F must be used. When addressing I/O Registers as data space using LD and ST
i n s t r u c t i o n s ,
ATmega640/1280/1281/2560/2561 is a complex microcontroller with more peripheral
units than can be supported within the 64 location reserved in Opcode for the IN and
OUT instructions. For the Extended I/O space from 0x60 - 0x1FF in SRAM, only the
ST/STS/STD and LD/LDS/LDD instructions can be used.
For compatibility with future devices, reserved bits should be written to zero if accessed.
Reserved I/O memory addresses should never be written.
Some of the Status Flags are cleared by writing a logical one to them. Note that, unlike
most other AVRs, the CBI and SBI instructions will only operate on the specified bit, and
can therefore be used on registers containing such Status Flags. The CBI and SBI
instructions work with registers 0x00 to 0x1F only.
The I/O and peripherals control registers are explained in later sections.
These registers can be used for storing any information, and they are particularly useful
for storing global variables and Status Flags. General Purpose I/O Registers within the
address range 0x00 - 0x1F are directly bit-accessible using the SBI, CBI, SBIS, and
SBIC instructions. See “Register Description” on page 32.
0 x 2 0
ATmega640/1280/1281/2560/2561
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