PIC18F4321 Datasheet, PDF (380/396 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC18F4321 FAMILY
APPENDIX C: CONVERSION
CONSIDERATIONS
This appendix discusses the considerations for
converting from previous versions of a device to the
ones listed in this data sheet. Typically, these changes
are due to the differences in the process technology
used. An example of this type of conversion is from a
PIC16C74A to a PIC16C74B.
The PIC18F4321 family of devices is functionally the
same as the PIC18F4320 family. Code written for a
PIC18F4320 will generally work on a PIC18F4321 with
few or no changes.
The following is a list of changes the user should be
aware of when migrating an application from the
PIC18F4320 to the PIC18F4321. Code written for the
PIC18F4321 may not run as expected due to these
differences.
1. Entry to power-managed modes has changed.
Modifying the SCS1:SCS0 bits (OSCCON<1:0>)
immediately changes the current clock source. It
is not necessary to execute a SLEEP instruction
to change clock sources. Refer to Section 3.1.2
“Entering Power-Managed Modes” for details.
2. Exit from power-managed modes has changed.
A WDT wake or interrupt does not cause an
automatic return to PRI_RUN mode. The
controller will execute code while continuing to
use the current clock source. If the controller
was operating in RC_IDLE or RC_RUN mode,
an interrupt will cause entry to RC_RUN mode
until code selects another power-managed
mode. Refer to Section 3.4 “Idle Modes” for
details.
3. The extended instruction set can be con-
figured as enabled using the XINST bit
(CONFIG4L<6>). The access memory map is
also modified when the extended instruction set
is enabled. Refer to Section 5.5 “Data Memory
and the Extended Instruction Set” and
Section 24.2 “Extended Instruction Set” for
details.
4. There may also be changes to the electrical spec-
ifications. Refer to Section 26.0 “Electrical
Characteristics” for details.
APPENDIX D: MIGRATION FROM
BASELINE TO
ENHANCED DEVICES
This section discusses how to migrate from a Baseline
device (i.e., PIC16C5X) to an Enhanced MCU device
(i.e., PIC18FXXX).
The following are the list of modifications over the
PIC16C5X microcontroller family:
Not Currently Available
DS39689E-page 378
Preliminary
© 2007 Microchip Technology Inc.