PIC18F87J72 datasheet(56/480 Pages) MICROCHIP

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PIC18F87J72 FAMILY

DS39979A-page 56

Preliminary

 2010 Microchip Technology Inc.

6.1.1

HARD MEMORY VECTORS

All PIC18 devices have a total of three hard-coded

return vectors in their program memory space. The

Reset vector address is the default value to which the

program counter returns on all device Resets; it is

located at 0000h.

PIC18 devices also have two interrupt vector

addresses for the handling of high-priority and

low-priority interrupts. The high-priority interrupt vector

is located at 0008h and the low-priority interrupt vector

is at 0018h. Their locations in relation to the program

memory map are shown in Figure 6-2.

FIGURE 6-2:

HARD VECTOR AND

CONFIGURATION WORD

LOCATIONS FOR

PIC18F87J72 FAMILY

FAMILY DEVICES

6.1.2

FLASH CONFIGURATION WORDS

Because PIC18F87J72 family devices do not have per-

sistent configuration memory, the top four words of

on-chip program memory are reserved for configuration

information. On Reset, the configuration information is

copied into the Configuration registers.

The Configuration Words are stored in their program

memory location in numerical order, starting with the

lower byte of CONFIG1 at the lowest address and end-

ing with the upper byte of CONFIG4. For these devices,

only

Configuration

Words,

CONFIG1

through

CONFIG3, are used; CONFIG4 is reserved. The actual

addresses of the Flash Configuration Word for devices

in the PIC18F87J72 family are shown in Table 6-1.

Their location in the memory map is shown with the

other memory vectors in Figure 6-2.

Additional details on the device Configuration Words

are provided in Section 26.1 “Configuration Bits”.

TABLE 6-1:

FLASH CONFIGURATION

WORD FOR PIC18F87J72

FAMILY DEVICES

Reset Vector

Low-Priority Interrupt Vector

0000h

0018h

On-Chip

Program Memory

High-Priority Interrupt Vector

0008h

1FFFFFh

(Top of Memory)

(Top of Memory-7)

Flash Configuration Words

Read ‘0’

Legend:

(Top of Memory) represents upper boundary

of on-chip program memory space (see

Figure 6-1 for device-specific values).

Shaded area represents unimplemented

memory. Areas are not shown to scale.

Device

Program

Memory

(Kbytes)

Configuration Word

Addresses

PIC18F86J72

FFF8h to FFFFh

PIC18F87J72

128

1FFF8h to 1FFFFh

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