ATMEGA644P-A15MZ Atmel, ATMEGA644P-A15MZ Datasheet - Page 284

• Manufacturer Part Number: ATMEGA644P-A15MZ
• Description: MCU AVR 64KB FLASH 16MHZ 44QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644P-A15MZ

• Package / Case: 44-VQFN Exposed Pad
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Speed: 16MHz
• Number Of I /o: 32
• Eeprom Size: 2K x 8
• Core Processor: AVR
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Program Memory Size: 64KB (64K x 8)
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Connectivity: I²C, SPI, UART/USART
• Core Size: 8-Bit
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

24.7
284
Addressing the Flash During Self-Programming
ATmega164P/324P/644P
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 24-3. Addressing the Flash During SPM
Note:
Bit
ZH (R31)
ZL (R30)
Z - REGISTER
1. The different variables used in
PROGRAM MEMORY
BIT
Z15
Z7
23
15
PAGE
PROGRAM
COUNTER
7
15
Figure
PAGE ADDRESS
WITHIN THE FLASH
ZPCMSB
PCMSB
Z14
22
14
Z6
24-3. Note that the Page Erase and Page Write operations are
6
PCPAGE
Z13
Z5
21
13
5
Figure 24-3
ZPAGEMSB
PAGEMSB
Table 25-7 on page
PCWORD
Z12
20
12
Z4
4
WORD ADDRESS
WITHIN A PAGE
(1)
are listed in
1
0
0
INSTRUCTION WORD
Z11
Z3
19
11
3
PAGE
Table 24-9 on page
299), the Program Counter can
Z10
18
10
Z2
2
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
Z9
Z1
17
291.
9
1
7674F–AVR–09/09
16
Z8
Z0
8
0