
20
AT89C51ID2
4289C–8051–11/05
–F
CLK CPU and FCLK PERIPH, for CKRL≠0xFF
In X2 Mode:
In X1 Mode:
Timer 0: Clock Inputs
Figure 1. Timer 0: Clock Inputs
Note:
The SCLKT0 bit in OSCCON register allows to select Timer 0 Subsidiary clock.
SCLKT0 = 0: Timer 0 uses the standard T0 pin as clock input (Standard mode)
SCLKT0 = 1: Timer 0 uses the special Sub Clock as clock input, this feature can be use
as periodic interrupt for time clock.
F
CPU
F
=
CLKPERIPH
F
OSCA
2255
CKRL
–
()
×
----------------------------------------------
=
F
CPU
F
=
CLKPERIPH
F
OSCA
4255
CKRL
–
()
×
----------------------------------------------
=
SCLKT0
1
0
FCLK PERIPH
:6
T0 pin
C/T
1
0
OSCCON
TMOD
Gate
INT0
TR0
Timer 0
Control
Sub Clock
(AT 8xC51Ix2 only)