ATmega32A datasheet(263/352 Pages) ATMEL

263 / 352 page

263

8155B–AVR–07/09

ATmega32A

25.8.13

Boot Loader Parameters

In Table 25-6 through Table 25-8, the parameters used in the description of the self program-

ming are given.

Note:

1. The different BOOTSZ Fuse configurations are shown in Figure 25-2

Note:

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

253 and “RWW – Read-While-Write Section” on page 253

Note:

1. Z15: always ignored

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

See “Addressing the Flash during Self-Programming” on page 257 for details about the use of

Z-pointer during Self-Programming.

Table 25-6.

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)

256

words

$0000 -

$3EFF

$3F00 -

$3FFF

$3EFF

$3F00

512

words

$0000 -

$3DFF

$3E00 -

$3FFF

$3DFF

$3E00

1024

words

$0000 -

$3BFF

$3C00 -

$3FFF

$3BFF

$3C00

2048

words

$0000 -

$37FF

$3800 -

$3FFF

$37FF

$3800

Table 25-7.

Read-While-Write Limit

(1)

Section

Pages

Address

Read-While-Write section (RWW)

224

$0000 - $37FF

No Read-While-Write section (NRWW)

$3800 - $3FFF

Table 25-8.

Explanation of Different Variables used in Figure 25-3 and the Mapping to the Z-

pointer

Variable

Corresponding

Z-value(1)

Description

PCMSB

Most significant bit in the Program Counter. (The

Program Counter is 14 bits PC[13:0])

PAGEMSB

Most significant bit which is used to address the

words within one page (64 words in a page requires

6 bits PC [5:0]).

ZPCMSB

Z14

Bit in Z-register that is mapped to PCMSB. Because

Z0 is not used, the ZPCMSB equals PCMSB + 1.

ZPAGEMSB

Bit in Z-register that is mapped to PAGEMSB.

Because Z0 is not used, the ZPAGEMSB equals

PAGEMSB + 1.

PCPAGE

PC[13:6]

Z14:Z7

Program Counter page address: Page select, for

page erase and page write

PCWORD

PC[5:0]

Z6:Z1

Program Counter word address: Word select, for

filling temporary buffer (must be zero during page

write operation)

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