PIC18F4580-ESLASHML datasheet(67/490 Pages) MICROCHIP

67 / 490 page

DS39637D-page 67

PIC18F2480/2580/4480/4580

6.0

MEMORY ORGANIZATION

There are three types of memory in PIC18 Enhanced

microcontroller devices:

• Program Memory

• Data RAM

• Data EEPROM

As Harvard architecture devices, the data and program

memories use separate busses; this allows for con-

current access of the two memory spaces. The data

EEPROM, for practical purposes, can be regarded as

a peripheral device, since it is addressed and accessed

through a set of control registers.

Additional detailed information on the operation of the

Flash program memory is provided in Section 7.0

“Flash Program Memory”. Data EEPROM is dis-

cussed separately in Section 8.0 “Data EEPROM

Memory”.

6.1

Program Memory Organization

PIC18 microcontrollers implement a 21-bit program

counter, which is capable of addressing a 2-Mbyte

program memory space. Accessing a location between

upper boundary of the physically implemented memory

and the 2-Mbyte address will return all ‘0’s (a NOP

instruction).

The PIC18F2480 and PIC18F4480 each have

16 Kbytes of Flash memory and can store up to

8,192 single-word instructions. The PIC18F2580 and

PIC18F4580 each have 32 Kbytes of Flash memory

and can store up to 16,384 single-word instructions.

PIC18 devices have two interrupt vectors. The Reset

vector address is at 0000h and the interrupt vector

addresses are at 0008h and 0018h.

The program memory maps for PIC18FX480 and

PIC18FX580 devices are shown in Figure 6-1.

FIGURE 6-1:

PROGRAM MEMORY MAP AND STACK FOR

PIC18F2480/2580/4480/4580 DEVICES

PC<20:0>

Stack Level 1

•

Stack Level 31

Reset Vector

Low-Priority Interrupt Vector

•

CALL,RCALL,RETURN

RETFIE,RETLW

0000h

0018h

On-Chip

Program Memory

High-Priority Interrupt Vector 0008h

1FFFFFh

4000h

3FFFh

Read ‘0’

200000h

PC<20:0>

Stack Level 1

•

Stack Level 31

Reset Vector

Low-Priority Interrupt Vector

•

CALL,RCALL,RETURN

RETFIE,RETLW

0000h

0018h

80000h

7FFFh

On-Chip

Program Memory

High-Priority Interrupt Vector 0008h

Read ‘0’

1FFFFFh

200000h

PIC18FX480

PIC18FX580

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