P89C51X2 데이터 시트보기 (PDF) - Philips Electronics
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P89C51X2 Datasheet PDF : 48 Pages
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Philips Semiconductors
80C51 8-bit Flash microcontroller family
4K/8K/16K/32K Flash
Preliminary data
P89C51X2/52X2/54X2/58X2
Mode 3 is provided for applications requiring an extra 8-bit timer on
the counter. With Timer 0 in Mode 3, an 80C51 can look like it has
three Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be
turned on and off by switching it out of and into its own Mode 3, or
can still be used by the serial port as a baud rate generator, or in
fact, in any application not requiring an interrupt.
TMOD
Address = 89H
Not Bit Addressable
Reset Value = 00H
7
6
5
4
3
2
1
0
GATE C/T M1 M0 GATE C/T
M1
M0
TIMER 1
TIMER 0
BIT
TMOD.3/
TMOD.7
TMOD.2/
TMOD.6
SYMBOL
GATE
C/T
M1 M0
00
01
10
11
11
FUNCTION
Gating control when set. Timer/Counter “n” is enabled only while “INTn” pin is high and
“TRn” control pin is set. when cleared Timer “n” is enabled whenever “TRn” control bit is set.
Timer or Counter Selector cleared for Timer operation (input from internal system clock.)
Set for Counter operation (input from “Tn” input pin).
OPERATING
8048 Timer: “TLn” serves as 5-bit prescaler.
16-bit Timer/Counter: “THn” and “TLn” are cascaded; there is no prescaler.
8-bit auto-reload Timer/Counter: “THn” holds a value which is to be reloaded
into “TLn” each time it overflows.
(Timer 0) TL0 is an 8-bit Timer/Counter controlled by the standard Timer 0 control bits.
TH0 is an 8-bit timer only controlled by Timer 1 control bits.
(Timer 1) Timer/Counter 1 stopped.
SU01580
Figure 1. Timer/Counter 0/1 Mode Control (TMOD) Register
OSC
÷ d*
Tn Pin
C/T = 0
C/T = 1
Control
TLn
(5 Bits)
THn
(8 Bits)
TRn
Timer n
Gate bit
INTn Pin
*d = 6 in 6-clock mode; d = 12 in 12-clock mode.
Figure 2. Timer/Counter 0/1 Mode 0: 13-Bit Timer/Counter
TFn
Interrupt
SU01618
2002 Jun 06
13
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