ATMEGA48A-PU Atmel, ATMEGA48A-PU Datasheet - Page 18
Manufacturer Part Number
IC MCU AVR 4K FLASH 28PDIP
Specifications of ATMEGA48A-PU
I²C, SPI, UART/USART
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
Program Memory Size
4KB (2K x 16)
Program Memory Type
256 x 8
512 x 8
Voltage - Supply (vcc/vdd)
1.8 V ~ 5.5 V
-40°C ~ 85°C
Package / Case
28-DIP (0.300", 7.62mm)
No. Of I/o's
Eeprom Memory Size
Ram Memory Size
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
SRAM Data Memory
The ATmega48A/48PA/88A/88PA/168A/168PA/328/328P is a complex microcontroller with
more peripheral units than can be supported within the 64 locations reserved in the 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.
The lower 768/1280/1280/2303 data memory locations address both the Register File, the I/O
memory, Extended I/O memory, and the internal data SRAM. The first 32 locations address the
Register File, the next 64 location the standard I/O memory, then 160 locations of Extended I/O
memory, and the next 512/1024/1024/2048 locations address the internal data SRAM.
The five different addressing modes for the data memory cover: Direct, Indirect with Displace-
ment, Indirect, Indirect with Pre-decrement, and Indirect with Post-increment. In the Register
File, registers R26 to R31 feature the indirect addressing pointer registers.
The direct addressing reaches the entire data space.
The Indirect with Displacement mode reaches 63 address locations from the base address given
by the Y- or Z-register.
When using register indirect addressing modes with automatic pre-decrement and post-incre-
ment, the address registers X, Y, and Z are decremented or incremented.
The 32 general purpose working registers, 64 I/O Registers, 160 Extended I/O Registers, and
t h e
ATmega48A/48PA/88A/88PA/168A/168PA/328/328P are all accessible through all these
addressing modes. The Register File is described in
5 1 2 / 1 0 2 4 / 1 0 2 4 / 2 0 4 8
shows how the ATmega48A/48PA/88A/88PA/168A/168PA/328/328P SRAM Memory
Data Memory Map
(512/1024/1024/2048 x 8)
160 Ext I/O Reg.
64 I/O Registers
b y t e s
i n t e r n a l
0x0000 - 0x001F
0x0020 - 0x005F
0x0060 - 0x00FF
”General Purpose Register File” on page
d a t a
S R A M
t h e