16F84 MICROCHIP [Microchip Technology], 16F84 Datasheet - Page 28

• Manufacturer Part Number: 16F84
• Description: 18-pin Flash/EEPROM 8-Bit Microcontrollers
• Manufacturer: MICROCHIP [Microchip Technology]

PIC16F8X
FIGURE 6-3:
FIGURE 6-4:
DS30430C-page 28
PC
Instruction
Fetch
TMR0
Instruction
Execute
INSTRUCTION FLOW
GIE bit
(INTCON<7>)
T0IF bit
(INTCON<2>)
Instruction
fetched
Instruction
executed
TMR0 timer
CLKOUT
OSC1
4
PC
(3)
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
Note 1: T0IF interrupt flag is sampled here (every Q1).
T0
PC-1
Q1
2: Interrupt latency = 3.25Tcy, where Tcy = instruction cycle time.
3: CLKOUT is available only in RC oscillator mode.
4: The timer clock (after the synchronizer circuit) which increments the timer from FFh to 00h immediately sets the T0IF bit.
TMR0 TIMING: INTERNAL CLOCK/PRESCALE 1:2
TMR0 INTERRUPT TIMING
The TMR0 register will roll over 3 Tosc cycles later.
FEh
Inst (PC)
Inst (PC-1)
Q2
1
PC
MOVWF TMR0
Q3
PC
T0+1
Q4
Q1
MOVF TMR0,W
FFh
Write TMR0
executed
Inst (PC+1)
Inst (PC)
PC+1
Q2
1
PC +1
Q3
MOVF TMR0,W MOVF TMR0,W
Read TMR0
reads NT0
Q4
PC+2
Q1
Interrupt Latency
00h
Dummy cycle
Q2
PC +1
Read TMR0
reads NT0
PC+3
Q3
NT0
(2)
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
Read TMR0
reads NT0 + 1
Inst (0004h)
Inst (0005h)
NT0+1
Q2
0005h
PC+6
Q3
Q4