PIC18F2220/2320/4220/4320
FIGURE 26-10:
TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS
T0CKI
41
40
42
T1OSO/T1CKI
46
45
47
48
TMR0 or
TMR1
Note:
Refer to Figure 26-5 for load conditions.
TABLE 26-11: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS
Param
Symbol
Characteristic
Min
Max Units
Conditions
No.
40
TT0H
T0CKI High Pulse Width
No prescaler
With prescaler
No prescaler
With prescaler
No prescaler
With prescaler
0.5 TCY + 20
10
—
—
—
—
—
—
ns
ns
ns
ns
ns
41
42
TT0L
TT0P
T0CKI Low Pulse Width
T0CKI Period
0.5 TCY + 20
10
TCY + 10
Greater of:
20 ns or TCY + 40
N
ns N = prescale
value
(1, 2, 4,..., 256)
45
46
TT1H
TT1L
T1CKI
High Time
Synchronous, no prescaler
0.5 TCY + 20
—
—
—
—
—
—
—
—
—
—
—
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Synchronous,
with prescaler
PIC18FXX20
10
PIC18LFXX20
25
Asynchronous PIC18FXX20
PIC18LFXX20
30
50
T1CKI
Low Time
Synchronous, no prescaler
0.5 TCY + 5
Synchronous,
with prescaler
PIC18FXX20
10
25
30
50
PIC18LFXX20
Asynchronous PIC18FXX20
PIC18LFXX20
47
48
TT1P
FT1
T1CKI
Input
Period
Synchronous
Greater of:
20 ns or TCY + 40
N
ns N = prescale
value
(1, 2, 4, 8)
Asynchronous
60
DC
—
50
ns
kHz
—
T1CKI Oscillator Input Frequency Range
TCKE2TMRI Delay from External T1CKI Clock Edge to
Timer Increment
2 TOSC
7 TOSC
2003 Microchip Technology Inc.
DS39599C-page 329
MICROCHIP [ MICROCHIP ]
