Datasheet
295
8272E–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
26.8.17 Atmel ATmega1284/ATmega1284P Boot Loader parameters
In Table 26-16 through Table 26-18, the parameters used in the description of the Self-Programming are given.
Note: 1. The different BOOTSZ Fuse configurations are shown in Figure 26-2 on page 283.
Note: 1. For details about these two section, see ”NRWW – No Read-While-Write Section” on page 281 and ”RWW – Read-While-
Write Section” on page 281.
Note: 1. Z0: should be zero for all SPM commands, byte select for the (E)LPM instruction.
See ”Addressing the Flash During Self-Programming” on page 285 for details about the use of Z-pointer during Self-
Programming.
Table 26-16. 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)
1 1 512 words 4 0x0000 - 0xFDFF 0xFE00 - 0xFFFF 0xFDFF 0xFE00
1 0 1024 words 8 0x0000 - 0xFBFF 0xFC00 - 0xFFFF 0xFBFF 0xFC00
0 1 2048 words 16 0x0000 - 0xF7FF 0xF800 - 0xFFFF 0xF7FF 0xF800
0 0 4096 words 32 0x0000 - 0xEFFF 0xF000 - 0xFFFF 0xEFFF 0xF000
Table 26-17. Read-While-Write limit
(1)
.
Section Pages Address
Read-While-Write section (RWW) 480 0x0000 - 0xEFFF
No Read-While-Write section (NRWW) 32 0xF000 - 0xFFFF
Table 26-18. Explanation of different variables used in Figure 26-3 on page 285 and the mapping to the Z-pointer.
Variable
Corresponding
Z-value Description
(1)
PCMSB 15
Most significant bit in the Program Counter. (The Program Counter is 16 bits
PC[15:0])
PAG EMSB 6
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 Z16
Bit in Z-pointer that is mapped to PCMSB. Because Z0 is not used, the ZPCMSB
equals PCMSB + 1.
ZPAGEMSB Z7
Bit in Z-pointer that is mapped to PCMSB. Because Z0 is not used, the
ZPAGEMSB equals PAGEMSB + 1.
PCPAGE PC[15:7] Z16:Z8 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)