P89C51X2 View Datasheet(PDF) - Philips Electronics

Part Name

Description

Manufacturer

P89C51X2

8-bit Flash microcontroller family 4K/8K/16K/32K Flash

Philips Electronics 

Philips Semiconductors

80C51 8-bit Flash microcontroller family

4K/8K/16K/32K Flash

Table 4. Timer 2 Operating Modes

RCLK + TCLK

CP/RL2

TR2

0

0

1

0

1

1

1

X

1

X

X

0

Preliminary data

P89C51X2/52X2/54X2/58X2

16-bit Auto-reload

16-bit Capture

Baud rate generator

(off)

MODE

T2CON Address = C8H

Bit Addressable

7

TF2

6

5

4

3

2

EXF2

RCLK

TCLK EXEN2

TR2

Reset Value = 00H

1

C/T2

0

CP/RL2

Symbol

TF2

EXF2

RCLK

TCLK

EXEN2

TR2

C/T2

CP/RL2

Position

T2CON.7

T2CON.6

T2CON.5

T2CON.4

T2CON.3

T2CON.2

T2CON.1

T2CON.0

Name and Significance

Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set

when either RCLK or TCLK = 1.

Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and

EXEN2 = 1. When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to vector to the Timer 2

interrupt routine. EXF2 must be cleared by software. EXF2 does not cause an interrupt in up/down

counter mode (DCEN = 1).

Receive clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock

in modes 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the receive clock.

Transmit clock flag. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock

in modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock.

Timer 2 external enable flag. When set, allows a capture or reload to occur as a result of a negative

transition on T2EX if Timer 2 is not being used to clock the serial port. EXEN2 = 0 causes Timer 2 to

ignore events at T2EX.

Start/stop control for Timer 2. A logic 1 starts the timer.

Timer or counter select. (Timer 2)

0 = Internal timer (OSC/12 in 12-clock mode or OSC/6 in 6-clock mode)

1 = External event counter (falling edge triggered).

Capture/Reload flag. When set, captures will occur on negative transitions at T2EX if EXEN2 = 1. When

cleared, auto-reloads will occur either with Timer 2 overflows or negative transitions at T2EX when

EXEN2 = 1. When either RCLK = 1 or TCLK = 1, this bit is ignored and the timer is forced to auto-reload

on Timer 2 overflow.

SU01621

Figure 6. Timer/Counter 2 (T2CON) Control Register

2002 Jun 06

16

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