ATMEGA64L-8MI View Datasheet(PDF) - Atmel Corporation
Part Name
Description
Manufacturer
ATMEGA64L-8MI
Atmel Corporation
ATMEGA64L-8MI Datasheet PDF : 363 Pages
| |||
ATmega64(L)
Addressing the Flash
During Self-
programming
The Z-pointer is used to address the SPM commands.
Bit
ZH (R31)
ZL (R30)
15
14
13
12
11
10
9
8
Z15
Z14
Z13
Z12
Z11
Z10
Z9
Z8
Z7
Z6
Z5
Z4
Z3
Z2
Z1
Z0
7
6
5
4
3
2
1
0
Since the Flash is organized in pages (see Table 124 on page 296), 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 is shown in Figure 137. Note that the Page Erase
and Page Write operations are addressed independently. Therefore, it is of major impor-
tance 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.
Figure 137. Addressing the Flash during SPM(1)Table 2 on page 283
BIT 15
Z - REGISTER
ZPCMSB
ZPAGEMSB 1 0
0
PCMSB
PROGRAM
COUNTER
PCPAGE
PAGE ADDRESS
WITHIN THE FLASH
PROGRAM MEMORY
PAGE
PAGEMSB
PCWORD
WORD ADDRESS
WITHIN A PAGE
PAGE
INSTRUCTION WORD
PCWORD[PAGEMSB:0]:
00
01
02
PAGEEND
Notes: 1. The different variables used in Figure 137 are listed in Table 114 on page 289.
2. PCPAGE and PCWORD are listed in Table 125 on page 296.
2490G–AVR–03/04
283
Share Link: 