PIC16C620 Microchip Technology, PIC16C620 Datasheet - Page 32

• Manufacturer Part Number: PIC16C620
• Description: EPROM-Based 8-Bit CMOS Microcontroller
• Manufacturer: Microchip Technology

PIC16C62X
FIGURE 6-3:
FIGURE 6-4:
DS30235G-page 32
Instruction
PC
(Program
Counter)
Fetch
TMR0
Instruction
Execute
INSTRUCTION FLOW
GIE bit
(INTCON<7>)
T0IF bit
(INTCON<2>)
Instruction
fetched
TMR0 timer
Instruction
executed
CLKOUT(3)
OSC1
PC
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
T0
Note 1: T0IF interrupt flag is sampled here (every Q1).
PC-1
Q1
TIMER0 TIMING: INTERNAL CLOCK/PRESCALE 1:2
TIMER0 INTERRUPT TIMING
2: Interrupt latency = 3T
3: CLKOUT is available only in RC oscillator mode.
FEh
Inst (PC)
Inst (PC-1)
Q2
PC
1
MOVWF TMR0
Q3
PC
T0+1
Q4
Q1
MOVF TMR0,W
FFh
CY
Write TMR0
executed
, where T
Inst (PC+1)
1
Inst (PC)
PC+1
Q2
PC +1
Q3
CY
= instruction cycle time.
MOVF TMR0,W MOVF TMR0,W
Preliminary
Read TMR0
reads NT0
Q4
PC+2
Q1
Interrupt Latency Time
00h
Dummy cycle
Q2
PC +1
Read TMR0
reads NT0
PC+3
Q3
NT0
Q4
MOVF TMR0,W
Read TMR0
reads NT0
Q1
PC+4
01h
Dummy cycle
Inst (0004h)
Q2
0004h
Q3
MOVF TMR0,W
Read TMR0
reads NT0
1998 Microchip Technology Inc.
PC+5
Q4
Q1
02h
NT0+1
Read TMR0
reads NT0 + 1
Inst (0004h)
Inst (0005h)
Q2
0005h
PC+6
Q3
Q4