PIC16C63A Microchip Technology, PIC16C63A Datasheet - Page 138

• Manufacturer Part Number: PIC16C63A
• Description: 28/40-Pin 8-Bit CMOS Microcontrollers
• Manufacturer: Microchip Technology

PIC16C63A/65B/73B/74B
APPENDIX D: MIGRATION FROM
This section discusses how to migrate from a baseline
device (i.e., PIC16C5X) to a midrange device (i.e.,
PIC16CXXX).
The following are the list of modifications over the
PIC16C5X microcontroller family:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. Wake up from SLEEP through interrupt is
11. Two separate timers, Oscillator Start-up Timer
12. PORTB has weak pull-ups and interrupt on
13. T0CKI pin is also a port pin (RA4) now.
14. FSR is made a full eight bit register.
15. “In-circuit serial programming” is made possible.
16. PCON status register is added with a Power-on
17. Code protection scheme is enhanced such that
DS30605A-page 138
Instruction word length is increased to 14-bits.
This allows larger page sizes both in program
memory (2K now as opposed to 512 before) and
register file (128 bytes now versus 32 bytes
before).
A PC high latch register (PCLATH) is added to
handle program memory paging. Bits PA2, PA1,
PA0 are removed from STATUS register.
Data memory paging is redefined slightly.
STATUS register is modified.
Four new instructions have been added:
RETURN, RETFIE, ADDLW, and SUBLW.
Two instructions TRIS and OPTION are being
phased out although they are kept for compati-
bility with PIC16C5X.
OPTION and TRIS registers are made address-
able.
Interrupt capability is added. Interrupt vector is
at 0004h.
Stack size is increased to 8 deep.
Reset vector is changed to 0000h.
Reset of all registers is revisited. Five different
reset (and wake-up) types are recognized. Reg-
isters are reset differently.
added.
(OST) and Power-up Timer (PWRT) are
included for more reliable power-up. These tim-
ers are invoked selectively to avoid unnecessary
delays on power-up and wake-up.
change feature.
The user can program PIC16CXX devices using
only five pins: V
and RB7 (data in/out).
Reset status bit (POR).
portions of the program memory can be pro-
tected, while the remainder is unprotected.
DD
BASELINE TO
MIDRANGE DEVICES
, V
SS
, MCLR/V
PP
, RB6 (clock)
18. Brown-out protection circuitry has been added.
To convert code written for PIC16C5X to PIC16CXXX,
the user should take the following steps:
1.
2.
3.
4.
5.
Controlled by configuration word bit BODEN.
Brown-out reset ensures the device is placed in
a reset condition if V
point.
Remove any program memory page select
operations (PA2, PA1, PA0 bits) for CALL, GOTO.
Revisit any computed jump operations (write to
PC or add to PC, etc.) to make sure page bits
are set properly under the new scheme.
Eliminate any data memory page switching.
Redefine data variables to reallocate them.
Verify all writes to STATUS, OPTION, and FSR
registers since these have changed.
Change reset vector to 0000h.
DD
1998 Microchip Technology Inc.
dips below a fixed set-