at89lp2052-20xi ATMEL Corporation, at89lp2052-20xi Datasheet - Page 25

• Manufacturer Part Number: at89lp2052-20xi
• Description: At89lp2052 8-bit Microcontroller With 2/4-kbyte Flash
• Manufacturer: ATMEL Corporation

16.3
16.4
3547H–MICRO–5/07
Mode 2
Mode 3
Mode 2 configures the Timer register as an 8-bit Counter (TL1) with automatic reload, as shown
in
TH1, which is preset by software. The reload leaves TH1 unchanged. Mode 2 operation is the
same for Timer/Counter 0.
Figure 16-3. Timer/Counter 1 Mode 2: 8-bit Auto-Reload
Timer 1 in Mode 3 simply holds its count. The effect is the same as setting TR1 = 0. Timer 0 in
Mode 3 establishes TL0 and TH0 as two separate counters. The logic for Mode 3 on Timer 0 is
shown in
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 for applications requiring an extra 8-bit timer or counter. With Timer 0 in Mode 3, the
AT89LP2052/LP4052 can appear to have 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. In this case,
Timer 1 can still be used by the serial port as a baud rate generator or in any application not
requiring an interrupt.
Figure 16-4. Timer/Counter 0 Mode 3: Two 8-bit Counters
Figure
INT0 Pin
Figure
16-3. Overflow from TL1 not only sets TF1, but also reloads TL1 with the contents of
GATE
T0 Pin
OSC
INT0 Pin
T1 Pin
GATE
16-4. TL0 uses the Timer 0 control bits: C/T, GATE, TR0, INT0, and TF0. TH0 is
TR1
C/T = 0
C/T =1
C/T = 0
C/T = 1
Control
Control
Control
(8 Bits)
(8 Bits)
(8 Bits)
(8 Bits)
TL1
TH1
AT89LP2052/LP4052
Reload
TF1
Interrupt
Interrupt
Interrupt
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