PIC17C4X Datasheet, PDF (117/240 Pages) Microchip Technology – High-Performance 8-Bit CMOS EPROM/ROM Microcontroller

PIC17C4X
CALL
Subroutine Call
Syntax:
[ label ] CALL k
Operands:
0 ≤ k ≤ 4095
Operation:
PC+ 1→ TOS, k → PC<12:0>,
k<12:8> → PCLATH<4:0>;
PC<15:13> → PCLATH<7:5>
Status Affected: None
Encoding:
111k kkkk kkkk kkkk
Description:
Subroutine call within 8K page. First,
return address (PC+1) is pushed onto
the stack. The 13-bit value is loaded into
PC bits<12:0>. Then the upper-eight
bits of the PC are copied into PCLATH.
Call is a two-cycle instruction.
See LCALL for calls outside 8K memory
space.
Words:
1
Cycles:
2
Q Cycle Activity:
Q1
Q2
Decode
Read literal
'k'<7:0>
Forced NOP NOP
Q3
Execute
Execute
Q4
NOP
NOP
Example:
HERE
CALL THERE
Before Instruction
PC = Address(HERE)
After Instruction
PC = Address(THERE)
TOS = Address (HERE + 1)
CLRF
Syntax:
Operands:
Operation:
Status Affected:
Encoding:
Description:
Words:
Cycles:
Q Cycle Activity:
Q1
Decode
Clear f
[label] CLRF f,s
0 ≤ f ≤ 255
00h → f, s ∈ [0,1]
00h → dest
None
0010 100s ffff ffff
Clears the contents of the specified reg-
ister(s).
s = 0: Data memory location 'f' and
WREG are cleared.
s = 1: Data memory location 'f' is
cleared.
1
1
Q2
Read
register 'f'
Q3
Execute
Q4
Write
register 'f'
and other
specified
register
Example:
CLRF
Before Instruction
FLAG_REG =
After Instruction
FLAG_REG =
FLAG_REG
0x5A
0x00
© 1996 Microchip Technology Inc.
DS30412C-page 117