PIC18F6525/6621/8525/8621
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
• PIC18F6525
• PIC18F6621
• PIC18F8525
• PIC18F8621
• 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 microcontrollers – namely, high computational
performance at an economical price – with the addition
of high-endurance Enhanced Flash program memory.
The PIC18F6525/6621/8525/8621 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 PIC18F6525/6621/8525/8621 family provides
ample room for application code and includes
members with 48 Kbytes or 64 Kbytes of code space.
1.1.4
OTHER SPECIAL FEATURES
• Communications: The PIC18F6525/6621/8525/
8621 family incorporates a range of serial communi-
Other memory features are:
cation peripherals, including
2
independent
• Data RAM and Data EEPROM: The PIC18F6525/
6621/8525/8621 family also provides plenty of room
for application data. The devices have 3840 bytes of
data RAM, as well as 1024 bytes of data EEPROM
for long term retention of nonvolatile data.
Enhanced USARTs and a Master SSP module capa-
ble of both SPI and I2C (Master and Slave) modes of
operation. Also, for PIC18F6525/6621/8525/8621
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.
• 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.
• CCP Modules: All devices in the family incorporate
two Capture/Compare/PWM (CCP) modules and
three Enhanced CCP (ECCP) modules to maximize
flexibility in control applications. Up to four different
time bases may be used to perform several different
operations at once. Each of the three ECCPs offer
up to four PWM outputs, allowing for a total of
12 PWMs. The ECCPs also offer many beneficial
features, including polarity selection, Programmable
Dead Time, Auto-Shutdown and Restart and
Half-Bridge and Full-Bridge Output modes.
1.1.2
EXTERNAL MEMORY INTERFACE
In the unlikely event that 64 Kbytes of program memory
is inadequate for an application, the PIC18F8525/8621
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 MBytes, permitting a level of data access that few
8-bit devices can claim.
• 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 and auto-acquisition conversions. Also
included are dual analog comparators with
programmable input and output configuration, a
programmable Low-Voltage Detect module and a
Programmable Brown-out Reset module.
• 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
program memory, it becomes possible to create an
application that can update itself in the field.
2005 Microchip Technology Inc.
DS39612B-page 7
MICROCHIP [ MICROCHIP ]
