W78L812A24DL(2006) Просмотр технического описания (PDF) - Winbond

Номер в каталоге

Компоненты Описание

Список матч

W78L812A24DL
(Rev.:2006)

8-BIT MICROCONTROLLER

Winbond 

W78LE812/W78L812A

5. FUNCTIONAL DESCRIPTION

The W78L812 architecture consists of a core controller surrounded by various registers, five general

purpose I/O ports, 256 bytes of RAM, three timer/counters, and a serial port. The processor supports

111 different opcodes and references both a 64K program address space and a 64K data storage

space.

5.1 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, TL2 and TH2 for Timer 2. The TCON and TMOD registers provide control

functions for timers 0 and 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 special feature of the W78L812: it is a 16-bit up/down

counter that is configured and controlled by the T2CON and T2MOD registers. 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. In

the auto-reload mode, Timer 2 performs a up counter which is similar with standard 8052. When

counting up, an overflow in Timer 2 will cause a reload from RCAP2H and RCAP2L registers. The

Timer 2 also provides a programmable clock-out mode as a clock generator. To enable this mode,

timer 2 has to be configured with a 16-bit auto-reload timer (C/T2 = 0, CP/RL2 = 0) and bit T2OE

(T2MOD.1) must be set to 1. This mode produces a 50% duty cycle clock output and timer 2 roll-overs

will not generate an interrupt. The clock-out frequency depends on the oscillator frequency and the

reload value of registers RCAP2H and RCAP2L. The clock-out frequency is determined by following

equation:

Clock-out Frequency = Oscillator Frequency / [4 × (65536-RCAP2H, RCAP2L)]

OSC

1/2

TL2 TH2

1/2

T2 (P1.0)

TR2 (T2CON.2)

T2EX (P1.1)

EXEN2 (T2CON.3)

Timer 2 Clock-Out Mode

RCAP2L RCAP2H

EXF2

T2CON.6

Timer 2

Interrupt

5.2 Timer 2 Mode Control

Bit:

7

6

5

4

3

2

1

0

-

-

-

-

-

-

T2OE

-

Mnemonic: T2MOD

Address: C9h

T2OE: Timer 2 Output Enable. This bit enables/disables the Timer 2 clock-out function.

Publication Release Date: November 6, 2006

-7-

Revision A9

Share Link: