PIC17C4X
The 4 Q cycles that make up an instruction cycle (Tcy)
can be generalized as:
15.2
Q Cycle Activity
Each instruction cycle (Tcy) is comprised of four Q
cycles (Q1-Q4). The Q cycles provide the timing/desig-
nation for the Decode, Read, Execute, Write etc., of
each instruction cycle. The following diagram shows
the relationship of the Q cycles to the instruction cycle.
Q1: Instruction Decode Cycle or forced NOP
Q2: Instruction Read Cycle or NOP
Q3: Instruction Execute
Q4: Instruction Write Cycle or NOP
Each instruction will show the detailed Q cycle opera-
tion for the instruction.
FIGURE 15-2: Q CYCLE ACTIVITY
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
Tosc
Tcy1
Tcy2
Tcy3
1996 Microchip Technology Inc.
DS30412C-page 109
MICROCHIP [ MICROCHIP ]
