AT89LP4052 Atmel Corporation, AT89LP4052 Datasheet - Page 26

• Manufacturer Part Number: AT89LP4052
• Manufacturer: Atmel Corporation

Specifications of AT89LP4052

• Flash (kbytes): 4 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 15
• Spi: 1
• Uart: 1
• Sram (kbytes): 0.25
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 2
• Isp: SPI
• Watchdog: Yes

16.3
16.4
26
Mode 2
Mode 3
AT89LP2052/LP4052
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)
TH1
TL1
Reload
TF1
Interrupt
3547J–MICRO–10/09
Interrupt
Interrupt