Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller SSOP 20 8-Bit 20 MHz I/O number 16

 2001-2013 Microchip Technology Inc. DS39598F-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

device’s 128 bytes of data EEPROM memory have the

address range of 00h-7Fh and the PIC16F819 device’s

256 bytes of data EEPROM memory have the address

range of 00h-FFh. More details on the EEPROM

memory can be found in Section 3.0 “Data EEPROM

and Flash Program Memory”.

Additional information on device memory may be found

in the “PIC

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