Datasheet

 1996 Microchip Technology Inc. DS30412C-page 117
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 Q3 Q4
Decode Read literal
'k'<7:0>
Execute NOP
Forced NOP NOP Execute NOP
Example:
HERE CALL THERE
Before Instruction
PC = Address(HERE)
After Instruction
PC = Address(THERE)
TOS = Address (HERE + 1)
CLRF Clear f
Syntax: [
label ] CLRF f,s
Operands: 0 ≤ f ≤ 255
Operation: 00h → f, s ∈ [0,1]
00h → dest
Status Affected: None
Encoding:
0010 100s ffff ffff
Description:
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.
Words: 1
Cycles: 1
Q Cycle Activity:
Q1 Q2 Q3 Q4
Decode Read
register 'f'
Execute Write
register 'f'
and other
specified
register
Example:
CLRF FLAG_REG
Before Instruction
FLAG_REG = 0x5A
After Instruction
FLAG_REG = 0x00