P89LV51RD2BA PHILIPS [NXP Semiconductors], P89LV51RD2BA Datasheet - Page 30

• Manufacturer Part Number: P89LV51RD2BA
• Description: 8-bit 80C51 3 V low power 64 kB Flash microcontroller with 1 kB RAM
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14342
Product data
7.3.3 Mode 2
7.3.4 Mode 3
Mode 2 configures the Timer register as an 8-bit Counter (TLn) with automatic reload,
as shown in
with the contents of THn, which must be preset by software. The reload leaves THn
unchanged. Mode 2 operation is the same for Timer 0 and Timer 1.
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 P89LV51RB2/RC2/RD2 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.
Fig 9. Timer/Counter 0 or 1 in Mode 1 (16-bit counter).
Fig 10. Timer/Counter 0 or 1 in Mode 2 (8-bit auto-reload).
INTn Pin
TnGate
Tn pin
INTn Pin
Osc/6
TnGate
TRn
Tn pin
Osc/6
TRn
Figure
Rev. 04 — 02 December 2004
10. Overflow from TLn not only sets TFn, but also reloads TLn
C/T = 0
C/T = 1
C/T = 0
C/T = 1
Figure
P89LV51RB2/RC2/RD2
control
control
11. TL0 uses the Timer 0 control bits:
8-bit microcontrollers with 80C51 core
(8-bits)
TLn
(8-bits)
(8-bits)
THn
TLn
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
reload
(8-bits)
THn
overflow
overflow
TFn
TFn
002aaa520
002aaa521
interrupt
interrupt
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