atmega32c1 ATMEL Corporation, atmega32c1 Datasheet - Page 28

• Manufacturer Part Number: atmega32c1
• Description: Atmega32m1 Automotive 8-bit Avr Microcontroller With 32k/64k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

4.4
4.5
4.5.1
4.5.2
4.5.3
28
I/O Memory
General Purpose I/O Registers
ATmega32/64/M1/C1
General Purpose I/O Register 0 – GPIOR0
General Purpose I/O Register 1 – GPIOR1
General Purpose I/O Register 2 – GPIOR2
The I/O space definition of the ATmega32/64/M1/C1 is shown in
346.
All ATmega32/64/M1/C1 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 instructions, 0x20 must be added to these addresses. The ATmega32/64/M1/C1 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.
The ATmega32/64/M1/C1 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.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
GPIOR07 GPIOR06 GPIOR05 GPIOR04 GPIOR03 GPIOR02 GPIOR01 GPIOR00
GPIOR17 GPIOR16 GPIOR15 GPIOR14 GPIOR13 GPIOR12 GPIOR11 GPIOR10
GPIOR27 GPIOR26 GPIOR25 GPIOR24 GPIOR23 GPIOR22 GPIOR21 GPIOR20
R/W
R/W
R/W
7
0
7
0
7
0
R/W
R/W
R/W
6
0
6
0
6
0
R/W
R/W
R/W
5
0
5
0
5
0
R/W
R/W
R/W
4
0
4
0
4
0
R/W
R/W
R/W
3
0
3
0
3
0
R/W
R/W
R/W
2
0
2
0
2
0
R/W
R/W
R/W
1
0
1
0
1
0
“Register Summary” on page
R/W
R/W
R/W
0
0
0
0
0
0
GPIOR0
GPIOR1
GPIOR2
7647A–AVR–02/08