ATMEGA644A-MUR Atmel, ATMEGA644A-MUR Datasheet - Page 282
![IC MCU AVR 64K FLASH 44VQFN](/photos/12/13/121316/313-44-qfn_sml.jpg)
ATMEGA644A-MUR
Manufacturer Part Number
ATMEGA644A-MUR
Description
IC MCU AVR 64K FLASH 44VQFN
Manufacturer
Atmel
Series
AVR® ATmegar
Specifications of ATMEGA644A-MUR
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
64KB (32K x 16)
Program Memory Type
FLASH
Eeprom Size
2K x 8
Ram Size
4K 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
44-VQFN Exposed Pad
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
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25.7
8272A–AVR–01/10
Addressing the Flash During Self-Programming
The Z-pointer is used to address the SPM commands. The Z pointer consists of the Z-registers
ZL and ZH in the register file
Since the Flash is organized in pages (see
be treated as having two different sections. One section, consisting of the least significant bits, is
addressing the words within a page, while the most significant bits are addressing the pages.
This is shown in
addressed independently. Therefore it is of major importance that the Boot Loader software
addresses the same page in both the Page Erase and Page Write operation. Once a program-
ming operation is initiated, the address is latched and the Z-pointer can be used for other
operations.
The LPM instruction use the Z-pointer to store the address. Since this instruction addresses the
Flash byte-by-byte, also bit Z0 of the Z-pointer is used.
Figure 25-3. Addressing the Flash During SPM
Note:
164A/164PA/324A/324PA/644A/644PA/1284/1284P
Bit
ZH (R31)
ZL (R30)
Z - REGISTER
1. The different variables used in
PROGRAM MEMORY
BIT
Z15
Z7
PAGE
15
PROGRAM
COUNTER
7
15
Figure
PAGE ADDRESS
WITHIN THE FLASH
ZPCMSB
PCMSB
Z14
Z6
14
25-3. Note that the Page Erase and Page Write operations are
6
PCPAGE
Z13
Z5
13
5
Figure 25-3
ZPAGEMSB
PAGEMSB
Table 26-7 on page
PCWORD
Z12
Z4
12
4
WORD ADDRESS
WITHIN A PAGE
(1)
are listed in
1
0
0
INSTRUCTION WORD
Z11
Z3
11
3
PAGE
Table 25-12 on page
298), the Program Counter can
Z10
Z2
10
2
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
Z9
Z1
9
1
290.
Z8
Z0
8
0
282
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