PIC18FXX20
With the addition of new Operating modes, the External
Memory Interface offers many new options, including:
1.0
DEVICE OVERVIEW
This document contains device specific information for
the following devices:
• Operating the microcontroller entirely from external
memory
• PIC18F6520
• PIC18F6620
• PIC18F6720
• PIC18F8520
• PIC18F8620
• PIC18F8720
• Using combinations of on-chip and external
memory, up to the 2 Mbyte limit
• Using external FLASH memory for reprogrammable
application code, or large data tables
• Using external RAM devices for storing large
amounts of variable data
This family offers the advantages of all PIC18 micro-
controllers - namely, high computational performance
at an economical price
- with the addition of
high-endurance Enhanced FLASH program memory.
The PIC18FXX20 family also provides an enhanced
range of program memory options and versatile analog
features that make it ideal for complex, high
performance applications.
1.1.3
EASY MIGRATION
Regardless of the memory size, all devices share the
same rich set of peripherals, allowing for a smooth
migration path as applications grow and evolve.
The consistent pinout scheme used throughout the
entire family also aids in migrating to the next larger
device. This is true when moving between the 64-pin
members, between the 80-pin members, or even
jumping from 64-pin to 80-pin devices.
1.1
Key Features
1.1.1
EXPANDED MEMORY
The PIC18FXX20 family introduces the widest range of
on-chip, Enhanced FLASH program memory available
on PICmicro® microcontrollers - up to 128 Kbyte (or
65,536 words), the largest ever offered by Microchip.
For users with more modest code requirements, the
family also includes members with 32 Kbyte or
64 KByte.
1.1.4
OTHER SPECIAL FEATURES
• Communications: The PIC18FXX20 family incor-
porates a range of serial communications peripher-
als, including 2 independent USARTs and a Master
SSP module, capable of both SPI and I2C (Master
and Slave) modes of operation. For PIC18F8X20
devices, one of the general purpose I/O ports can be
reconfigured as an 8-bit Parallel Slave Port for direct
processor-to-processor communications.
• CCP Modules: All devices in the family incorporate
5 Capture/Compare/PWM modules to maximize
flexibility in control applications. Up to four different
time-bases may be used to perform several different
operations at once.
Other memory features are:
• Data RAM and Data EEPROM: The PIC18FXX20
family also provides plenty of room for application
data. Depending on the device, either 2048 or
3840 bytes of data RAM are available. All devices
have 1024 bytes of data EEPROM for long-term
retention of non-volatile data.
• Memory Endurance: The Enhanced FLASH cells
for both program memory and data EEPROM are
rated to last for many thousands of erase/write
cycles - up to 100,000 for program memory, and
1,000,000 for EEPROM. Data retention without
refresh is conservatively estimated to be greater
than 40 years.
• Analog Features: All devices in the family feature
10-bit A/D converters, with up to 16 input channels,
as well as the ability to perform conversions during
SLEEP mode. Also included are dual analog com-
parators with programmable input and output config-
uration,
a programmable Low Voltage Detect
module, and a Programmable Brown-out Reset
module.
1.1.2
EXTERNAL MEMORY INTERFACE
In the unlikely event that 128 Kbyte of program memory
is inadequate for an application, the PIC18F8X20
members of the family also implement an External
Memory Interface. This allows the controller’s internal
program counter to address a memory space of up to
2 MByte, permitting a level of data access that few 8-bit
devices can claim.
• Self-programmability: These devices can write to
their own program memory spaces under internal
software control. By using a bootloader routine
located in the protected Boot Block at the top of pro-
gram memory, it becomes possible to create an
application that can update itself in the field.
2003 Microchip Technology Inc.
Advance Information
DS39609A-page 7
MICROCHIP [ MICROCHIP ]
