Datasheet

 2010-2013 Microchip Technology Inc. DS39881E-page 209
PIC24FJ64GA004 FAMILY
24.0 SPECIAL FEATURES
PIC24FJ64GA004 family devices include several
features intended to maximize application flexibility and
reliability, and minimize cost through elimination of
external components. These are:
• Flexible Configuration
• Watchdog Timer (WDT)
• Code Protection
• JTAG Boundary Scan Interface
• In-Circuit Serial Programming
• In-Circuit Emulation
24.1 Configuration Bits
The Configuration bits can be programmed (read as ‘0’),
or left unprogrammed (read as ‘1’), to select various
device configurations. These bits are mapped starting at
program memory location, F80000h. A complete list of
locations is shown in Table 24-1. A detailed explanation
of the various bit functions is provided in Register 24-1
through Register 24-4.
Note that address, F80000h, is beyond the user program
memory space. In fact, it belongs to the configuration
memory space (800000h-FFFFFFh), which can only be
accessed using table reads and table writes.
24.1.1 CONSIDERATIONS FOR
CONFIGURING PIC24FJ64GA004
FAMILY DEVICES
In PIC24FJ64GA004 family devices, the configuration
bytes are implemented as volatile memory. This means
that configuration data must be programmed each time
the device is powered up. Configuration data is stored
in the two words at the top of the on-chip program
memory space, known as the Flash Configuration
Words. Their specific locations are shown in
Table 24-1. These are packed representations of the
actual device Configuration bits, whose actual
locations are distributed among five locations in config-
uration space. The configuration data is automatically
loaded from the Flash Configuration Words to the
proper Configuration registers during device Resets.
TABLE 24-1: FLASH CONFIGURATION
WORD LOCATIONS FOR
PIC24FJ64GA004 FAMILY
DEVICES
When creating applications for these devices, users
should always specifically allocate the location of the
Flash Configuration Word for configuration data. This is
to make certain that program code is not stored in this
address when the code is compiled.
The Configuration bits are reloaded from the Flash
Configuration Word on any device Reset.
The upper byte of both Flash Configuration Words in
program memory should always be ‘1111 1111’. This
makes them appear to be NOP instructions in the
remote event that their locations are ever executed by
accident. Since Configuration bits are not implemented
in the corresponding locations, writing ‘1’s to these
locations has no effect on device operation.
Note: This data sheet summarizes the features
of this group of PIC24F devices. It is not
intended to be a comprehensive refer-
ence source. For more information, refer
to the following sections of the “PIC24F
Family Reference Manual”:
• “Watchdog Timer (WDT)”
(DS39697)
• “High-Level Device Integration”
(DS39719)
• “Programming and Diagnostics”
(DS39716)
Note: Configuration data is reloaded on all types
of device Resets.
Device
Configuration Word
Addresses
12
PIC24FJ16GA 002BFEh 002BFCh
PIC24FJ32GA 0057FEh 0057FCh
PIC24FJ48GA 0083FEh 0083FCh
PIC24FJ64GA 00ABFEh 00ABFCh