ATMEGA324PA-PU Atmel, ATMEGA324PA-PU Datasheet - Page 14

MCU AVR 32KB FLASH 40PDIP

ATMEGA324PA-PU

Manufacturer Part Number
ATMEGA324PA-PU
Description
MCU AVR 32KB FLASH 40PDIP
Manufacturer
Atmel
Series
AVR® ATmegar

Specifications of ATMEGA324PA-PU

Core Processor
AVR
Core Size
8-Bit
Speed
20MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
32
Program Memory Size
32KB (16K x 16)
Program Memory Type
FLASH
Eeprom Size
1K x 8
Ram Size
2K x 8
Voltage - Supply (vcc/vdd)
1.8 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
40-DIP (0.600", 15.24mm)
Controller Family/series
AVR MEGA
No. Of I/o's
32
Eeprom Memory Size
1KB
Ram Memory Size
2KB
Cpu Speed
20MHz
Rohs Compliant
Yes
For Use With
ATSTK600 - DEV KIT FOR AVR/AVR32
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
6.4.1
6.5
8272A–AVR–01/10
Stack Pointer
The X-register, Y-register, and Z-register
The registers R26..R31 have some added functions to their general purpose usage. These reg-
isters are 16-bit address pointers for indirect addressing of the data space. The three indirect
address registers X, Y, and Z are defined as described in
Figure 6-3.
In the different addressing modes these address registers have functions as fixed displacement,
automatic increment, and automatic decrement (see the instruction set reference for details).
The Stack is mainly used for storing temporary data, for storing local variables and for storing
return addresses after interrupts and subroutine calls. Note that the Stack is implemented as
growing from higher to lower memory locations. The Stack Pointer Register always points to the
top of the Stack. The Stack Pointer points to the data SRAM Stack area where the Subroutine
and Interrupt Stacks are located. A Stack PUSH command will decrease the Stack Pointer.
The Stack in the data SRAM must be defined by the program before any subroutine calls are
executed or interrupts are enabled. Initial Stack Pointer value equals the last address of the
internal SRAM and the Stack Pointer must be set to point above start of the SRAM, see
7-2 on page
See
Table 6-1.
The AVR Stack Pointer is implemented as two 8-bit registers in the I/O space. The number of
bits actually used is implementation dependent, see
space in some implementations of the AVR architecture is so small that only SPL is needed. In
this case, the SPH Register will not be present.
164A/164PA/324A/324PA/644A/644PA/1284/1284P
X-register
Y-register
Z-register
Instruction
PUSH
CALL
ICALL
RCALL
POP
RET
RETI
Table 6-1
21.
The X-, Y-, and Z-registers
Stack Pointer instructions
Stack pointer
Decremented by 1
Decremented by 2
Incremented by 1
Incremented by 2
for Stack Pointer details.
15
7
R27 (0x1B)
15
7
R29 (0x1D)
15
7
R31 (0x1F)
Description
Data is pushed onto the stack
Return address is pushed onto the stack with a subroutine call or
interrupt
Data is popped from the stack
Return address is popped from the stack with return from
subroutine or return from interrupt
XH
YH
ZH
0
Table 6-2 on page
0
0
Figure
7
R26 (0x1A)
7
R28 (0x1C)
7
R30 (0x1E)
6-3.
15. Note that the data
XL
YL
ZL
0
Figure
14
0
0
0
0
0

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