AT89LP51 Atmel Corporation, AT89LP51 Datasheet - Page 60

• Manufacturer Part Number: AT89LP51
• Manufacturer: Atmel Corporation

Specifications of AT89LP51

• Flash (kbytes): 4 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 36
• Uart: 1
• Sram (kbytes): 0.25
• Eeprom (bytes): 256
• Self Program Memory: IAP
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 3
• Isp: SPI
• Watchdog: Yes

Table 14-2.
14.2.2
60
Modes 1, 3 Max: 750K
Mode 0 Max: 6 MHz
Mode 2 Max: 750K
Baud Rate
19.2K
19.2K
137.5
137.5
AT89LP51/52
9.6K
4.8K
2.4K
1.2K
9.6K
4.8K
2.4K
1.2K
110
110
110
110
Using Timer 2 to Generate Baud Rates
Commonly Used Baud Rates Generated by Timer 1
The Timer 1 overflow rate normally determines the baud rates in Modes 1 and 3. When Timer 1
is the baud rate generator, the baud rates are determined by the Timer 1 overflow rate and the
value of SMOD1 according to the following equation:
The Timer 1 interrupt should be disabled in this application. The Timer itself can be configured
for either timer or counter operation in any of its 3 running modes. In the most typical applica-
tions, it is configured for timer operation in auto-reload mode (high nibble of TMOD = 0010B). In
this case, the baud rate is given by the following formula:
Table 14-2
Timer 2 is selected as the baud rate generator by setting TCLK and/or RCLK in T2CON. Under
these conditions, the baud rates for transmit and receive can be simultaneously different by
using Timer 1 for transmit and Timer 2 for receive, or vice versa. The baud rate generator mode
f
OSC
11.059
11.059
11.059
11.059
11.059
11.986
11.059
11.059
11.059
11.059
11.059
11.986
12
12
12
12
12
(MHz)
6
6
lists commonly used baud rates and how they can be obtained from Timer 1.
CDV
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
Modes 1, 3
Baud Rate
Modes 1, 3
Baud Rate
SMOD1
1
1
1
1
0
0
0
0
0
1
0
1
0
0
0
0
0
0
0
=
2
------------------- -
=
SMOD1
32
2
------------------- -
SMOD1
32
C/T
×
X
X
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
System Frequency
------------------------------------------------- -
×
[
(Timer 1 Overflow Rate)
256
–
(
Mode
TH1
X
X
2
2
2
2
2
1
1
1
1
2
2
2
2
2
2
2
1
)
]
Timer 1
×
-------------------- -
TPS
TPS
1
0
0
0
0
0
0
0
0
0
0
0
5
5
5
5
5
5
5
5
+
1
3709D–MICRO–12/11
Reload Value
FEEBH
FEE0H
F55CH
F2AFH
F2AFH
DCH
DCH
B8H
FDH
FDH
E8H
1DH
F4H
70H
FAH
F4H
72H
X
X