AT90PWM81 View Datasheet(PDF) - Atmel Corporation
Part Name
Description
MFG CO.
'AT90PWM81' PDF : 325 Pages View PDF
AT90PWM81/161
4.5 I/O Memory
The I/O space definition of the AT90PWM81/161 is shown in “Register Summary” on page 297.
All AT90PWM81/161 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 Summary” on page 301 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 instructions, 0x20 must be added to these addresses. The
AT90PWM81/161 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 - 0xFF 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
AVR’s, 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.
4.6 General Purpose I/O Registers
The AT90PWM81/161 contains four 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.
The General Purpose I/O Registers, within the address range 0x00 - 0x1F, are directly bit-
accessible using the SBI, CBI, SBIS, and SBIC instructions.
4.6.1
4.6.2
4.6.3
GPIOR0 - General Purpose I/O Register 0
Bit
Read/Write
Initial Value
7
GPIOR07
R/W
0
6
GPIOR06
R/W
0
5
GPIOR05
R/W
0
4
GPIOR04
R/W
0
3
GPIOR03
R/W
0
2
GPIOR02
R/W
0
1
GPIOR01
R/W
0
0
GPIOR00
R/W
0
GPIOR0
GPIOR1 - General Purpose I/O Register 1
Bit
Read/Write
Initial Value
7
GPIOR17
R/W
0
6
GPIOR16
R/W
0
5
GPIOR15
R/W
0
4
GPIOR14
R/W
0
3
GPIOR13
R/W
0
2
GPIOR12
R/W
0
1
GPIOR11
R/W
0
0
GPIOR10
R/W
0
GPIOR1
GPIOR2 - General Purpose I/O Register 2
Bit
Read/Write
Initial Value
7
GPIOR27
R/W
0
6
GPIOR26
R/W
0
5
GPIOR25
R/W
0
4
GPIOR24
R/W
0
3
GPIOR23
R/W
0
2
GPIOR22
R/W
0
1
GPIOR21
R/W
0
0
GPIOR20
R/W
0
GPIOR2
26
7734Q–AVR–02/12
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