PIC17C42 Microchip Technology, PIC17C42 Datasheet - Page 109

• Manufacturer Part Number: PIC17C42
• Description: High-Performance 8-Bit CMOS EPROM/ROM Microcontroller
• Manufacturer: Microchip Technology

15.2
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.
FIGURE 15-2: Q CYCLE ACTIVITY
1996 Microchip Technology Inc.
Q Cycle Activity
Tosc
Q1
Q2
Tcy1
Q3
Q4
Q1
Q2
Tcy2
Q3
The 4 Q cycles that make up an instruction cycle (Tcy)
can be generalized as:
Each instruction will show the detailed Q cycle opera-
tion for the instruction.
Q1: Instruction Decode Cycle or forced NOP
Q2: Instruction Read Cycle or NOP
Q3: Instruction Execute
Q4: Instruction Write Cycle or NOP
Q4
Q1
Q2
Tcy3
Q3
Q4
PIC17C4X
DS30412C-page 109