A000047 Arduino, A000047 Datasheet - Page 322

• Manufacturer Part Number: A000047
• Description: MCU, MPU & DSP Development Tools Mega2560
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000047

• Processor To Be Evaluated: ATmega2560
• Interface Type: USB, I2C, SPI
• Dimensions: 4 in x 2.1 in
• Operating Supply Voltage: 5 V
• Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega2560

28.5
2549M–AVR–09/10
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, and RAMPZ in the I/O space. The number of bits actually used is
implementation dependent. Note that the RAMPZ register is only implemented when the pro-
gram space is larger than 64 Kbytes.
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 (E)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 28-3. Addressing the Flash During SPM
Note:
Bit
RAMPZ
ZH (R31)
ZL (R30)
Z - REGISTER
The different variables used in
PROGRAM MEMORY
BIT
RAMPZ7
Z15
Z7
PAGE
23
15
PROGRAM
COUNTER
7
15
Figure
PAGE ADDRESS
WITHIN THE FLASH
ZPCMSB
RAMPZ6
PCMSB
Z14
Z6
22
14
28-3. Note that the Page Erase and Page Write operations are
6
PCPAGE
ATmega640/1280/1281/2560/2561
RAMPZ5
Figure 28-3
Z13
Z5
21
13
5
ZPAGEMSB
PAGEMSB
Table 29-7 on page
PCWORD
RAMPZ4
Z12
are listed in
Z4
20
12
4
WORD ADDRESS
WITHIN A PAGE
(Note:)
1
0
0
RAMPZ3
INSTRUCTION WORD
Z11
Table 28-9 on page
19
11
Z3
3
PAGE
338), the Program Counter can
RAMPZ2
Z10
Z2
18
10
2
PCWORD[PAGEMSB:0]:
329.
00
01
02
PAGEEND
RAMPZ1
Z9
Z1
17
9
1
RAMPZ0
16
Z8
Z0
8
0
322