PIC16F818/819
FIGURE 15-8:
TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
RA4/T0CKI
41
40
42
RB6/T1OSO/T1CKI
46
45
47
48
TMR0 or TMR1
Note: Refer to Figure 15-3 for load conditions.
TABLE 15-4: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param
No.
Symbol
TT0H
Characteristic
T0CKI High Pulse Width
Min
Typ† Max Units
Conditions
40*
No Prescaler
With Prescaler
No Prescaler
With Prescaler
No Prescaler
With Prescaler
0.5 TCY + 20
10
—
—
—
—
—
—
—
—
—
—
—
—
ns Must also meet
parameter 42
ns
41*
42*
TT0L
TT0P
T0CKI Low Pulse Width
T0CKI Period
0.5 TCY + 20
10
ns Must also meet
parameter 42
ns
TCY + 40
ns
Greater of:
20 or TCY + 40
N
ns N = prescale value
(2, 4, ..., 256)
45*
46*
47*
TT1H
TT1L
TT1P
T1CKI High
Time
Synchronous, Prescaler = 1
0.5 TCY + 20
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
ns Must also meet
parameter 47
Synchronous,
Prescaler = 2,4,8
PIC16F818/819
PIC16LF818/819
PIC16F818/819
PIC16LF818/819
15
ns
25
ns
Asynchronous
30
ns
50
ns
T1CKI Low Time Synchronous, Prescaler = 1
0.5 TCY + 20
ns Must also meet
parameter 47
Synchronous,
PIC16F818/819
15
25
30
50
ns
Prescaler = 2,4,8
PIC16LF818/819
PIC16F818/819
PIC16LF818/819
PIC16F818/819
ns
ns
ns
Asynchronous
Synchronous
T1CKI Input
Period
Greater of:
30 or TCY + 40
N
ns N = prescale
value (1, 2, 4, 8)
PIC16LF818/819
Greater of:
50 or TCY + 40
N
N = prescale
value (1, 2, 4, 8)
Asynchronous
PIC16F818/819
PIC16LF818/819
60
100
DC
—
—
—
—
—
ns
ns
FT1
Timer1 Oscillator Input Frequency Range
(Oscillator enabled by setting bit T1OSCEN)
32.768 kHz
48
TCKEZTMR1 Delay from External Clock Edge to Timer Increment
2 TOSC
—
7 TOSC
—
*
These parameters are characterized but not tested.
† Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested.
DS39598E-page 134
2004 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
