Datasheet

15.4.6. Port B Data Direction Register
When addressing I/O Registers as data space using LD and ST instructions, the provided offset must be
used. When using the I/O specific commands IN and OUT, the offset is reduced by 0x20, resulting in an
I/O address offset within 0x00 - 0x3F.
The device is a complex microcontroller with more peripheral units than can be supported within the 64
locations reserved in Opcode for the IN and OUT instructions. For the Extended I/O space from 0x60 in
SRAM, only the ST/STS/STD and LD/LDS/LDD instructions can be used.
Name: DDRB
Offset: 0x24
Reset: 0x00
Property: When addressing as I/O Register: address offset is 0x04
Bit 7 6 5 4 3 2 1 0
DDRB7 DDRB6 DDRB5 DDRB4 DDRB3 DDRB2 DDRB1 DDRB0
Access
R/W R/W R/W R/W R/W R/W R/W R/W
Reset 0 0 0 0 0 0 0 0
Bits 0, 1, 2, 3, 4, 5, 6, 7 – DDRBn: Port B Data Direction
This bit field selects the data direction for the individual pins in the Port. When a Port is mapped as virtual,
accessing this bit field is identical to accessing the actual DIR register for the Port.
Atmel ATmega644A [DATASHEET]
Atmel-42716C-ATmega644A_Datasheet_Complete-10/2016
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