PIC18F2331 Datasheet, PDF (59/396 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with nanoWatt Technology, High Performance PWM and A/D

PIC18F2331/2431/4331/4431
5.0 MEMORY ORGANIZATION
There are three memory types in enhanced MCU
devices. These memory types are:
• Program Memory
• Data RAM
• Data EEPROM
Data and program memory use separate busses,
which allows for concurrent access of these types.
Additional detailed information for Flash program mem-
ory and data EEPROM is provided in Section 6.0
“Flash Program Memory” and Section 7.0 “Data
EEPROM Memory”, respectively.
FIGURE 5-1:
PROGRAM MEMORY MAP
AND STACK FOR
PIC18F2331/4331
PC<20:0>
CALL,RCALL,RETURN
21
RETFIE,RETLW
Stack Level 1
••
•
Stack Level 31
Reset Vector LSb
000000h
High Priority Interrupt Vector LSb 000008h
Low Priority Interrupt Vector LSb ^000018h
On-Chip Flash
Program Memory
001FFFh
002000h
Unused -
Read ‘0’s
5.1 Program Memory Organization
A 21-bit program counter is capable of addressing the
2-Mbyte program memory space. Accessing a location
between the physically implemented memory and the
2-Mbyte address will cause a read of all ‘0’s (a NOP
instruction).
The PIC18F2331 and PIC18F4331 each have
8 Kbytes of Flash memory and can store up to 4,096
single-word instructions.
The PIC18F2431 and PIC18F4431 each have
16 Kbytes of Flash memory and can store up to 8,192
single-word instructions.
The Reset vector address is at 000000h and the
interrupt vector addresses are at 000008h and
000018h.
The Program Memory Maps for PIC18F2X31 and
PIC18F4X31 devices are shown in Figure 5-1 and
Figure 5-2, respectively.
FIGURE 5-2:
PROGRAM MEMORY MAP
AND STACK FOR
PIC18F2431/4431
PC<20:0>
CALL,RCALL,RETURN
21
RETFIE,RETLW
Stack Level 1
•
••
Stack Level 31
Reset Vector LSb
000000h
High Priority Interrupt Vector LSb ^000008h
Low Priority Interrupt Vector LSb ^000018h
On-Chip Flash
Program Memory
003FFFh
004000h
Unused -
Read ‘0’s
1FFFFFh
1FFFFFh
 2003 Microchip Technology Inc.
Preliminary
DS39616B-page 57