ATMEGA48V_11 ATMEL [ATMEL Corporation], ATMEGA48V_11 Datasheet - Page 274

• Manufacturer Part Number: ATMEGA48V_11
• Description: 8-bit Atmel Microcontroller with 4/8/16K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

27.7
2545T–AVR–05/11
Addressing the flash during self-programming
Table 27-4.
Note:
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 is1 shown in
tions are 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
programming 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.
Bit
ZH (R31)
ZL (R30)
BOOTRST
1
0
1. “1” means unprogrammed, “0” means programmed.
Boot reset fuse
Z15
15
Z7
7
Reset address
Reset vector = Application reset (address 0x0000)
Reset vector = Boot loader reset (see
Figure 27-3 on page
Z14
14
Z6
6
(1)
.
Z13
13
Z5
5
275. Note that the Page Erase and Page Write opera-
Table 28-9 on page
Z12
12
Z4
4
Table 27-6 on page
Z11
11
Z3
3
ATmega48/88/168
Z10
10
Z2
2
289), the Program Counter can
281)
Z9
Z1
9
1
Z8
Z0
8
0
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