Atmel ATmega328P Xplained Mini MEGA328P-XMINI MEGA328P-XMINI 数据表
产品代码
MEGA328P-XMINI
269
ATmega48A/PA/88A/PA/168A/PA/328/P [DATASHEET]
Atmel-8271H-AVR- ATmega-Datasheet_08/2014
27.7
Addressing the Flash During Self-Programming
The Z-pointer is used to address the SPM commands.
), the Program Counter can 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
a page, while the most significant bits are addressing the pages. This is1 shown in
. Note that the
Page Erase and Page Write operations 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 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.
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.
Figure 27-3.
Addressing the Flash During SPM
Note:
1. The different variables used in
are listed in
Bit
15
14
13
12
11
10
9
8
ZH (R31)
Z15
Z14
Z13
Z12
Z11
Z10
Z9
Z8
ZL (R30)
Z7
Z6
Z5
Z4
Z3
Z2
Z1
Z0
7
6
5
4
3
2
1
0
PROGRAM MEMORY
0
1
15
Z - REGISTER
BIT
0
ZPAGEMSB
WORD ADDRESS
WITHIN A PAGE
WITHIN A PAGE
PAGE ADDRESS
WITHIN THE FLASH
WITHIN THE FLASH
ZPCMSB
INSTRUCTION WORD
PAGE
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
PAGE
PCWORD
PCPAGE
PCMSB
PAGEMSB
PROGRAM
COUNTER
COUNTER