Datasheet

ManualsBrandsMicrochip ManualsEmbedded Processors & ControllersMicrocontroller DIL-18

 2002 Microchip Technology Inc. Preliminary DS39598C-page 9

PIC16F818/819

2.0 MEMORY ORGANIZATION

There are two memory blocks in the PIC16F818/819.

These are the program memory and the data memory.

Each block has its own bus, so access to each block

can occur during the same oscillator cycle.

The data memory can be further broken down into the

general purpose RAM and the Special Function

Registers (SFRs). The operation of the SFRs that

control the “core” are described here. The SFRs used

to control the peripheral modules are described in the

section discussing each individual peripheral module.

The data memory area also contains the data

EEPROM memory. This memory is not directly

mapped into the data memory, but is indirectly

mapped. That is, an indirect address pointer specifies

the address of the data EEPROM memory to read/

write. The PIC16F818’s 128 bytes of data EEPROM

memory have the address range 00h-7Fh, and the

PIC16F819’s 256 bytes of data EEPROM memory

have the address range 00h-FFh. More details on the

EEPROM memory can be found in Section 3.0.

Additional information on device memory may be found

in the PICmicro™ Mid-Range Reference Manual,

(DS33023).

FIGURE 2-1: PROGRAM MEMORY MAP

AND STACK FOR

PIC16F818

2.1 Program Memory Organization

The PIC16F818/819 devices have a 13-bit program

counter capable of addressing an 8K x 14 program

memory space. For the PIC16F818, the first 1K x 14

(0000h-03FFh) is physically implemented (see

Figure 2-1). For the PIC16F819, the first 2K x 14 is

located at 0000h-07FFh (see Figure 2-2). Accessing a

location above the physically implemented address will

cause a wraparound. For example, the same instruc-

tion will be accessed at locations 020h, 420h, 820h,

C20h, 1020h, 1420h, 1820h, and 1C20h.

The RESET vector is at 0000h and the interrupt vector

is at 0004h.

FIGURE 2-2: PROGRAM MEMORY MAP

AND STACK FOR

PIC16F819

PC<12:0>

0000h

0004h

0005h

Stack Level 1

Stack Level 8

RESET Vector

Interrupt Vector

On-Chip

CALL, RETURN

RETFIE, RETLW

1FFFh

Stack Level 2

Program

Memory

Page 0

03FFh

0400h

Wraps to

0000h - 03FFh