W78LE365/W78L365A
5.2
Timers 0, 1 and 2
Timers 0, 1, and 2 each consist of two 8-bit data registers. These are called TL0 and TH0 for Timer 0,
TL1 and TH1 for Timer 1, and TL2 and TH2 for Timer 2. The TCON and TMOD registers provide
control functions for timers 0, 1. The T2CON register provides control functions for Timer 2. RCAP2H
and RCAP2L are used as reload/capture registers for Timer 2. The operations of Timer 0 and Timer 1
are the same as in the W78C51. Timer 2 is a 16-bit timer/counter that is configured and controlled by
the T2CON register. Like Timers 0 and 1, Timer 2 can operate as either an external event counter or
as an internal timer, depending on the setting of bit C/T2 in T2CON. Timer 2 has three operating
modes: capture, auto-reload, and baud rate generator. The clock speed at capture or auto-reload
mode is the same as that of Timers 0 and 1.
5.2.1
Timer 2 Output
If set T2OE (T2MOD.1) bit and clear C/T2 (T2CON.1) bit at auto-reload mode, P1.0 will be toggled
once overflow.
TIMER 2 Mode
Bit:
7
6
5
4
3
2
1
T2OE
0
Mnemonic: T2MOD
Address: C9H
T2OE: Enable this bit to toggle P1.0 pin while Timer2 has been overflowed.
5.3
Clock
The W78L365A is designed with either a crystal oscillator or an external clock. Internally, the clock is
divided by two before it is used by default. This makes the W78L365A relatively insensitive to duty
cycle variations in the clock.
5.3.1
Crystal Oscillator
The W78L365A incorporates a built-in crystal oscillator. To make the oscillator work, a crystal must be
connected across pins XTAL1 and XTAL2. In addition, a load capacitor must be connected from each
pin to ground.
5.3.2
External Clock
An external clock should be connected to pin XTAL1. Pin XTAL2 should be left unconnected. The
XTAL1 input is a CMOS-type input, as required by the crystal oscillator.
-7-
Publication Release Date: January 10, 2007
Revision A7
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