Datasheet

 1998-2013 Microchip Technology Inc. DS30289C-page 199

PIC17C7XX

18.2 Q Cycle Activity

Each instruction cycle (TCY) is comprised of four Q

cycles (Q1-Q4). The Q cycle is the same as the device

oscillator cycle (T

OSC). The Q cycles provide the timing/

designation for the Decode, Read, Process Data,

Write, etc., of each instruction cycle. The following dia-

gram shows the relationship of the Q cycles to the

instruction cycle.

The four Q cycles that make up an instruction cycle

CY) can be generalized as:

Q1: Instruction Decode Cycle or forced No

operation

Q2: Instruction Read Cycle or No operation

Q3: Process the Data

Q4: Instruction Write Cycle or No operation

Each instruction will show the detailed Q cycle opera-

tion for the instruction.

FIGURE 18-2: Q CYCLE ACTIVITY

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

TCY1TCY2TCY3

OSC