ATmega324P datasheet(293/377 Pages) ATMEL

293 / 377 page

293

7674F–AVR–09/09

ATmega164P/324P/644P

24.8.16

ATmega644P Boot Loader Parameters

In Table 24-13 through Table 24-15, the parameters used in the description of the Self-Programming are given.

Note:

1. The different BOOTSZ Fuse configurations are shown in Figure 24-2 on page 282.

Note:

1. For details about these two section, see “NRWW – No Read-While-Write Section” on page 280 and “RWW –

Read-While-Write Section” on page 280.

Note:

1. Z0: should be zero for all SPM commands, byte select for the LPM instruction.

See “Addressing the Flash During Self-Programming” on page 284 for details about the use of Z-pointer during

Self-Programming.

Table 24-13. Boot Size Configuration

(1)

BOOTSZ1

BOOTSZ0

Boot Size

Pages

Application

Flash Section

Boot Loader

Flash Section

End Application

Section

Boot Reset

Address

(Start Boot

Loader Section)

512 words

0x0000 - 0xFDFF

0xFE00 - 0x7FFF

0xFDFF

0xFE00

1024 words

0x0000 - 0xFBFF

0xFC00 - 0x7FFF

0xFBFF

0xFC00

2048 words

0x0000 - 0xF7FF

0xF800 - 0x7FFF

0xF7FF

0xF800

4096 words

0x0000 - 0xEFFF

0xF000 - 0x7FFF

0xEFFF

0xF000

Table 24-14. Read-While-Write Limit

(1)

Section

Pages

Address

Read-While-Write section (RWW)

224

0x0000 - 0xEFFF

No Read-While-Write section (NRWW)

0xF000 - 0xFFFF

Table 24-15.

Explanation of different variables used in Figure 24-3 on page 284 and the mapping to the Z-pointer

Variable

Correspondi

Z-value

Description(1)

PCMSB

Most significant bit in the Program Counter. (The Program Counter is 15 bits

PC[14:0])

PAGEMSB

Most significant bit which is used to address the words within one page (128

words in a page requires seven bits PC [6:0]).

ZPCMSB

Z15

Bit in Z-pointer that is mapped to PCMSB. Because Z0 is not used, the ZPCMSB

equals PCMSB + 1.

ZPAGEMSB

Bit in Z-pointer that is mapped to PCMSB. Because Z0 is not used, the

ZPAGEMSB equals PAGEMSB + 1.

PCPAGE

PC[14:7]

Z15:Z7

Program Counter page address: Page select, for Page Erase and Page Write

PCWORD

PC[6:0]

Z7:Z1

Program Counter word address: Word select, for filling temporary buffer (must be

zero during Page Write operation)

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