ATMEGA325A-MU Atmel, ATMEGA325A-MU Datasheet - Page 272

• Manufacturer Part Number: ATMEGA325A-MU
• Description: IC MCU AVR 32K FLASH 64VQFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA325A-MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 54
• 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: 64-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

25.7
272
Addressing the Flash During Self-Programming
ATmega165A/165PA/325A/325PA/3250A/3250PA/645A/645P/645
The Z-pointer is used to address the SPM commands.
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 only SPM operation that does not use the Z-pointer is Setting the Boot Loader Lock bits.
The content of the Z-pointer is ignored and will have no effect on the operation. The LPM
instruction does also use the Z-pointer to store the address. Since this instruction addresses the
Flash byte-by-byte, also the LSB (bit Z0) of the Z-pointer is used.
Figure 25-3. Addressing the Flash During SPM
Note:
Bit
ZH (R31)
ZL (R30)
Z - REGISTER
1. The different variables used in
2. PCPAGE and PCWORD are listed in
PROGRAM MEMORY
BIT
PAGE
PROGRAM
COUNTER
15
Z15
Z7
15
7
Figure
PAGE ADDRESS
WITHIN THE FLASH
ZPCMSB
PCMSB
Z14
Z6
25-3. Note that the Page Erase and Page Write operations are
14
6
PCPAGE
Z13
Z5
13
5
Figure 25-3
ZPAGEMSB
PAGEMSB
Table 26-7 on page
PCWORD
Z12
12
Z4
Table 26-7 on page
4
WORD ADDRESS
WITHIN A PAGE
(1)
are listed in
1
Z11
0
0
11
Z3
3
INSTRUCTION WORD
PAGE
Table 25-8 on page
Z10
10
Z2
286.
2
286), the Program Counter can
Z9
Z1
9
1
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
279.
Z8
Z0
8
0
8285B–AVR–03/11