
PIC16C7X
DS30390B-page 60
1995 Microchip Technology Inc.
FIGURE 7-3:
TIMER0 TIMING: INTERNAL CLOCK/PRESCALE 1:2
FIGURE 7-4:
TIMER0 INTERRUPT TIMING
PC+6
PC-1
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
PC
(Program
Counter)
Instruction
Fetch
TMR0
PC
PC+1
PC+2
PC+3
PC+4
PC+5
PC+6
T0
NT0+1
MOVWF TMR0
MOVF TMR0,W
MOVF TMR0,W
MOVF TMR0,W
MOVF TMR0,W
MOVF TMR0,W
Write TMR0
executed
Read TMR0
reads NT0
Read TMR0
reads NT0
Read TMR0
reads NT0
Read TMR0
reads NT0
Read TMR0
reads NT0 + 1
T0+1
NT0
Instruction
Execute
Q2
Q1
Q3
Q4
Q2
Q1
Q3
Q4
Q2
Q1
Q3
Q4
Q2
Q1
Q3
Q4
Q2
Q1
Q3
Q4
1
1
OSC1
CLKOUT
(3)
Timer0
T0IF bit
(INTCON<2>)
FEh
GIE bit
(INTCON<7>)
INSTRUCTION
FLOW
PC
Instruction
fetched
PC
PC +1
PC +1
0004h
0005h
Instruction
executed
Inst (PC)
Inst (PC-1)
Inst (PC+1)
Inst (PC)
Inst (0004h)
Inst (0005h)
Inst (0004h)
Dummy cycle
Dummy cycle
FFh
00h
01h
02h
Note 1: Interrupt flag bit T0IF is sampled here (every Q1).
2: Interrupt latency = 4Tcy where Tcy = instruction cycle time.
3: CLKOUT is available only in RC oscillator mode.