AT89LP216 Atmel Corporation, AT89LP216 Datasheet - Page 29

• Manufacturer Part Number: AT89LP216
• Manufacturer: Atmel Corporation

Specifications of AT89LP216

• Flash (kbytes): 2 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 14
• Spi: 1
• Uart: 1
• Sram (kbytes): 0.125
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 2
• Isp: SPI/OCD
• Watchdog: Yes

14.3
14.4
3621E–MICRO–11/10
Mode 2 – 8-bit Auto-reload Timer/Counter
Mode 3 – 8-bit Split Timer
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 14-3. Timer/Counter 1 Mode 2: 8-bit Auto-reload
Note:
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. While Timer 0 is in Mode 3, Timer 1
will still obey its settings in TMOD but cannot generate an interrupt.
Mode 3 is for applications requiring an extra 8-bit timer or counter. With Timer 0 in Mode 3, the
AT89LP216 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 14-4. Timer/Counter 0 Mode 3: Two 8-bit Counters
Note:
Figure
RH1/RL1 are not required by Timer 1 during Mode 2 and may be used as temporary storage
registers.
RH0/RL0 are not required by Timer 0 during Mode 3 and may be used as temporary storage
registers.
Figure
14-3. Overflow from TL1 not only sets TF1, but also reloads TL1 with the contents of
Mode 2:
14-4. TL0 uses the Timer 0 control bits: C/T, GATE, TR0, INT0, and TF0. TH0 is
INT0 Pin
GATE
T0 Pin
OSC
INT0 Pin
T1 Pin
GATE
Time-out Period
÷TPS
÷TPS
÷TPS
TR1
C/T = 0
C/T =1
C/T = 0
C/T = 1
=
Control
Control
Control
------------------------------------------------------ -
Oscillator Frequency
(
(8 Bits)
(8 Bits)
256 TH0
(8 Bits)
(8 Bits)
TH1
TL1
–
Reload
)
TF1
×
(
Interrupt
Interrupt
Interrupt
TPS
AT89LP216
+
1
)
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