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8266A-MCU Wireless-12/09
8.6 General Purpose I/O Registers
The ATmega128RFA1 contains three General Purpose I/O Registers. 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.
8.6.1 GPIOR0 – General Purpose IO Register 0
Bit 7 6 5 4 3 2 1 0
$1E ($3E) GPIOR07:00 GPIOR0
Read/Write RW RW RW RW RW RW RW RW
Initial Value 0 0 0 0 0 0 0 0
The three General Purpose I/O Registers can be used for storing any information.
• Bit 7:0 – GPIOR07:00 - General Purpose I/O Register 0 Value
8.6.2 GPIOR1 – General Purpose IO Register 1
Bit 7 6 5 4 3 2 1 0
$2A ($4A) GPIOR17:10 GPIOR1
Read/Write RW RW RW RW RW RW RW RW
Initial Value 0 0 0 0 0 0 0 0
The three General Purpose I/O Registers can be used for storing any information.
• Bit 7:0 – GPIOR17:10 - General Purpose I/O Register 1 Value
8.6.3 GPIOR2 – General Purpose I/O Register 2
Bit 7 6 5 4 3 2 1 0
$2B ($4B) GPIOR27:20 GPIOR2
Read/Write RW RW RW RW RW RW RW RW
Initial Value 0 0 0 0 0 0 0 0
The three General Purpose I/O Registers can be used for storing any information.
• Bit 7:0 – GPIOR27:20 - General Purpose I/O Register 2 Value
8.7 Other Port Registers
The inherited control registers of missing ports located in the I/O space are kept in the
ATmega128RFA1. They can be used as general purpose I/O registers for storing any
information. Registers placed in the address range 0x00 – 0x1F are directly bit-
accessible using the SBI, CBI, SBIS and SBIC instructions.
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