PIC16C54C-04-P Datasheet, PDF (31/192 Pages) Microchip Technology – EPROM/ROM-Based 8-bit CMOS Microcontroller Series

6.5 Program Counter
As a program instruction is executed, the Program
Counter (PC) will contain the address of the next pro-
gram instruction to be executed. The PC value is
increased by one, every instruction cycle, unless an
instruction changes the PC.
For a GOTO instruction, bits 8:0 of the PC are provided
by the GOTO instruction word. The PC Latch (PCL) is
mapped to PC<7:0> (Figure 6-7, Figure 6-8 and
Figure 6-9).
For the PIC16C56, PIC16CR56, PIC16C57,
PIC16CR57, PIC16C58 and PIC16CR58, a page num-
ber must be supplied as well. Bit5 and bit6 of the STA-
TUS Register provide page information to bit9 and
bit10 of the PC (Figure 6-8 and Figure 6-9).
For a CALL instruction, or any instruction where the
PCL is the destination, bits 7:0 of the PC again are pro-
vided by the instruction word. However, PC<8> does
not come from the instruction word, but is always
cleared (Figure 6-7 and Figure 6-8).
Instructions where the PCL is the destination, or modify
PCL instructions, include MOVWF PCL, ADDWF PCL,
and BSF PCL,5.
For the PIC16C56, PIC16CR56, PIC16C57,
PIC16CR57, PIC16C58 and PIC16CR58, a page num-
ber again must be supplied. Bit5 and bit6 of the STA-
TUS Register provide page information to bit9 and
bit10 of the PC (Figure 6-8 and Figure 6-9).
Note:
Because PC<8> is cleared in the CALL
instruction, or any modify PCL instruction,
all subroutine calls or computed jumps are
limited to the first 256 locations of any pro-
gram memory page (512 words long).
FIGURE 6-7:
LOADING OF PC
BRANCH INSTRUCTIONS
- PIC16C54, PIC16CR54,
PIC16C55
GOTO Instruction
87
0
PC
PCL
Instruction Word
CALL or Modify PCL Instruction
87
0
PC
PCL
Reset to '0' Instruction Word
PIC16C5X
FIGURE 6-8:
LOADING OF PC
BRANCH INSTRUCTIONS
- PIC16C56/PIC16CR56
GOTO Instruction
10 9 8 7
0
PC 0
PCL
Instruction Word
2 PA<1:0>
7
0
0
STATUS
CALL or Modify PCL Instruction
10 9 8 7
0
PC 0
PCL
Instruction Word
Reset to ‘0’
2 PA<1:0>
7
0
0
STATUS
FIGURE 6-9:
LOADING OF PC
BRANCH INSTRUCTIONS
- PIC16C57/PIC16CR57,
AND PIC16C58/
PIC16CR58
GOTO Instruction
10 9 8 7
0
PC
PCL
Instruction Word
2 PA<1:0>
7
0
STATUS
CALL or Modify PCL Instruction
10 9 8 7
0
PC
PCL
Instruction Word
Reset to ‘0’
2 PA<1:0>
7
0
STATUS
 1997-2013 Microchip Technology Inc.
Preliminary
DS30453E-page 31