PIC17C7XX Datasheet, PDF (197/328 Pages) Microchip Technology – High-Performance 8-Bit CMOS EPROM Microcontrollers with 10-bit A/D

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 (TOSC). The Q cycles provide the tim-
ing/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
(TCY) 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
Tosc
TCY1
TCY2
TCY3
© 1998 Microchip Technology Inc.
DS30289A-page 197