ATmega168A Atmel Corporation, ATmega168A Datasheet - Page 19
Manufacturer Part Number
Specifications of ATmega168A
Max. Operating Frequency
# Of Touch Channels
Hardware Qtouch Acquisition
Max I/o Pins
Adc Resolution (bits)
Adc Speed (ksps)
Resistive Touch Screen
Self Program Memory
Temp. Range (deg C)
-40 to 85
I/o Supply Class
1.8 to 5.5
Operating Voltage (vcc)
1.8 to 5.5
Mpu / Mmu
no / no
Output Compare Channels
Input Capture Channels
Calibrated Rc Oscillator
SRAM Data Memory
The ATmega48A/PA/88A/PA/168A/PA/328/P 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/PA/88A/PA/168A/PA/328/P 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/PA/88A/PA/168A/PA/328/P SRAM Memory is
Data Memory Map
(512/1024/1024/2048 x 8)
160 Ext I/O Reg.
64 I/O Registers
”General Purpose Register File” on page
b y t e s
i n t e r n a l
0x0000 - 0x001F
0x0020 - 0x005F
0x0060 - 0x00FF
d a t a
S R A M
t h e