PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 39

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

4.0
There are three memory blocks in Enhanced MCU
devices. These memory blocks are:
• Enhanced FLASH Program Memory
• Data Memory
• EEPROM Data Memory
Data and program memory use separate busses,
which allows concurrent access of these blocks. Addi-
tional detailed information on Data EEPROM and
FLASH program memory is provided in Section 5.0 and
Section 6.0, respectively.
4.1
The PIC18F258/458 devices have a 21-bit program
counter that is capable of addressing a 2 Mbyte
program memory space.
The RESET vector address is at 0000h and the
interrupt vector addresses are at 0008h and 0018h.
FIGURE 4-1:
 2002 Microchip Technology Inc.
CALL,RCALL,RETURN
RETFIE,RETLW
MEMORY ORGANIZATION
Program Memory Organization
High Priority Interrupt Vector 0008h
Low Priority Interrupt Vector
Stack Level 31
RESET Vector
Stack Level 1
On-Chip
Program Memory
PC<20:0>
Read ’0’
•
•
•
PROGRAM MEMORY MAP
AND STACK FOR
PIC18F258/458
21
0000h
0018h
7FFFh
8000h
1FFFFFh
200000h
Preliminary
Figure 4-1 shows the diagram for program memory
map and stack for the PIC18F258 and PIC18F458.
Figure 4-2 shows the the diagram for the program
memory map and stack for the PIC18F248 and
PIC18F448.
4.1.1
The PIC18F258 and the PIC18F458 have 32 Kbytes of
internal Enhanced FLASH program memory. This
means that the PIC18F258 and the PIC18F458 can
store up to 16K of single word instructions. The
PIC18F248 and PIC18F448 have 16 Kbytes of
Enhanced FLASH program memory. This translates
into 8192 single-word instructions, which can be stored
in the Program memory. Accessing a location between
the physically implemented memory and the 2 Mbyte
address will cause a read of all '0's (a NOP instruction).
FIGURE 4-2:
CALL,RCALL,RETURN
RETFIE,RETLW
High Priority Interrupt Vector 0008h
Low Priority Interrupt Vector
INTERNAL PROGRAM MEMORY
OPERATION
Stack Level 31
RESET Vector
Stack Level 1
On-Chip
Program Memory
PC<20:0>
Read ’0’
•
•
•
PROGRAM MEMORY MAP
AND STACK FOR
PIC18F248/448
PIC18FXX8
21
0000h
0018h
3FFFh
4000h
1FFFFFh
200000h
DS41159B-page 37