
Philips Semiconductors
Preliminary specification
87LPC764
Low power, low price, low pin count (20 pin)
microcontroller with 4 kB OTP
2000 Jun 01
29
Mode 1
Mode 1 is the same as Mode 0, except that all 16 bits of the timer
register (THn and TLn) are used. See Figure 25
Mode 2
Mode 2 configures the Timer register as an 8-bit Counter (TL1) with
automatic reload, as shown in Figure 26. Overflow from TLn not only
sets TFn, but also reloads TLn 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.
Mode 3
When Timer 1 is in Mode 3 it is stopped. 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 on Timer 0 is shown in Figure 27.
TL0 uses the Timer 0 control bits: C/T, GATE, 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, an 87LPC764 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 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.
SU01174
TLN
(8-BITS)
THN
(8-BITS)
OSC/6
OR
OSC/12
OVERFLOW
Tn PIN
TnOE
TOGGLE
CONTROL
C/T = 1
C/T = 0
Tn PIN
TRn
GATE
INTn PIN
INTERRUPT
TFn
Figure 25. Timer/Counter 0 or 1 in Mode 1 (16-Bit Counter)
SU01392
TLN
(8-BITS)
THN
(8-BITS)
OSC/6
OR
OSC/12
OVERFLOW
Tn PIN
TnOE
TOGGLE
CONTROL
C/T = 1
C/T = 0
Tn PIN
TRn
GATE
INTn PIN
INTERRUPT
TFn
RELOAD
Figure 26. Timer/Counter 0 or 1 in Mode 2 (8-Bit Auto-Reload)