AT90USB1286-16MU ATMEL [ATMEL Corporation], AT90USB1286-16MU Datasheet - Page 360

• Manufacturer Part Number: AT90USB1286-16MU
• Description: Microcontroller with 64/128K Bytes of ISP Flash and USB Controller
• Manufacturer: ATMEL [ATMEL Corporation]

28.6
360
Addressing the Flash During Self-Programming
AT90USB64/128
Note:
The Z-pointer is used to address the SPM commands. The Z pointer consists of the Z-registers
ZL and ZH in the register file, and RAMPZ in the I/O space. The number of bits actually used is
implementation dependent. Note that the RAMPZ register is only implemented when the pro-
gram space is larger than 64K bytes.
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 is shown in
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 program-
ming operation is initiated, the address is latched and the Z-pointer can be used for other
operations.
The (E)LPM instruction use the Z-pointer to store the address. Since this instruction addresses
the Flash byte-by-byte, also bit Z0 of the Z-pointer is used.
Figure 28-4. Addressing the Flash During SPM
Bit
RAMPZ
ZH (R31)
ZL (R30)
PROGRAM COUNTER
Only one SPM instruction should be active at any time.
BIT
PROGRAM MEMORY
23
15
RAMPZ7
Z15
Z7
7
23
PAGE
Figure
PAGE ADDRESS
WITHIN THE FLASH
22
14
RAMPZ6
Z14
Z6
6
ZPCMSB
PCMSB
28-4. Note that the Page Erase and Page Write operations are
PCPAGE
21
13
RAMPZ5
Z13
Z5
5
20
12
RAMPZ4
Z12
Z4
4
ZPAGEMSB
PAGEMSB
Table 29-11 on page
PCWORD
WORD ADDRESS
WITHIN A PAGE
(1)
19
11
RAMPZ3
Z11
Z3
3
1
0
0
INSTRUCTION WORD
Z - POINTER
18
10
RAMPZ2
Z10
Z2
2
PAGE
373), the Program Counter can
17
9
RAMPZ1
Z9
Z1
1
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
16
8
RAMPZ0
Z8
Z0
0
7593A–AVR–02/06