P89V51RD2 Philips Semiconductors, P89V51RD2 Datasheet - Page 28

• Manufacturer Part Number: P89V51RD2
• Description: 8-bit 80C51 5 V low power 64 kB Flash microcontroller with 1 kB RAM
• Manufacturer: Philips Semiconductors

Philips Semiconductors
9397 750 12964
Product data
7.3.4 Mode 3
7.4 Timer 2
When timer 1 is in Mode 3 it is stopped (holds its count). The effect is the same as
setting TR1 = 0.
Timer 0 in Mode 3 establishes TL0 and TH0 as two separate 8-bit counters. The logic
for Mode 3 and Timer 0 is shown in
T0C/T, T0GATE, TR0, INT0, and TF0. TH0 is locked into a timer function (counting
machine cycles) and takes over the use of TR1 and TF1 from Timer 1. Thus, TH0
now controls the ‘Timer 1’ interrupt.
Mode 3 is provided for applications that require an extra 8-bit timer. With Timer 0 in
Mode 3, the P89V51RD2 can look like it has an additional Timer.
Note: When Timer 0 is in Mode 3, Timer 1 can be turned on and off by switching it
into and out of its own Mode 3. It can still be used by the serial port as a baud rate
generator, or in any application not requiring an interrupt.
Timer 2 is a 16-bit Timer/Counter which can operate as either an event timer or an
event counter, as selected by C/T2 in the special function register T2CON. Timer 2
has four operating modes: Capture, Auto-reload (up or down counting), Clock-out,
and Baud Rate Generator which are selected according to
(Table 18
Fig 9. Timer/Counter 0 or 1 in Mode 2 (8-bit auto-reload).
Fig 10. Timer/Counter 0 Mode 3 (two 8-bit counters).
INTn Pin
INT0 Pin
TnGate
TnGate
Tn pin
T0 pin
Osc/6
Osc/6
TRn
TR0
and
Table
Rev. 01 — 01 March 2004
19) and T2MOD
Osc/2
TR1
C/T = 0
C/T = 1
C/T = 0
C/T = 1
Figure
(Table 20
control
control
control
10. TL0 uses the Timer 0 control bits:
8-bit microcontrollers with 80C51 core
and
(8-bits)
(8-bits)
(8-bits)
(8-bits)
THn
TH0
TLn
TL0
Table
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
reload
21).
overflow
overflow
overflow
Table 17
P89V51RD2
TFn
TF0
TF1
using T2CON
002aaa521
002aaa522
interrupt
interrupt
interrupt
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