AT89LP51RD2 Atmel Corporation, AT89LP51RD2 Datasheet - Page 112

• Manufacturer Part Number: AT89LP51RD2
• Manufacturer: Atmel Corporation

Specifications of AT89LP51RD2

• Flash (kbytes): 64 Kbytes
• Max. Operating Frequency: 20 MHz
• Cpu: 8051-1C
• Max I/o Pins: 42
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Adc Channels: 7
• Adc Resolution (bits): 10
• Adc Speed (ksps): 153.8
• Sram (kbytes): 2.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.4 to 5.5
• Timers: 4
• Isp: SPI/OCD/UART
• Watchdog: Yes

17.2.1
112
AT89LP51RD2/ED2/ID2 Preliminary
Using Timer 1 to Generate Baud Rates
Table 17-2.
Setting TB8 = 1 in Mode 0 enables Timer 1 as the baud rate generator. When Timer 1 is the
baud rate generator for Mode 0, the baud rates are determined by the Timer 1 overflow rate and
the value of SMOD1 according to the following equation:
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 17-3
(T2CON.4)
TCLK
0
1
0
1
X
X
0
1
X
lists commonly used baud rates and how they can be obtained from Timer 1.
UART Baud Rate Selection Table for Modes 1 and 3
(T2CON.5)
Mode 0 Baud Rate
Modes 1, 3
RCLK
Baud Rate
0
0
1
1
0
1
X
X
X
Modes 1, 3
Baud Rate
TB8 = 1
=
(BDRCON.3)
2
------------------- -
=
TBCK
SMOD1
32
2
------------------- -
0
0
0
0
1
1
0
0
1
=
SMOD1
32
2
------------------- -
SMOD1
×
4
System Frequency
------------------------------------------------- -
×
[
(BDRCON.2)
(Timer 1 Overflow Rate)
256
×
RBCK
(Timer 1 Overflow Rate)
–
0
0
0
0
0
0
1
1
1
(
TH1
)
]
Clock Source
×
UART Tx
Timer 1
Timer 2
Timer 1
Timer 2
Timer 1
Timer 2
-------------------- -
TPS
BRG
BRG
BRG
1
+
1
3714A–MICRO–7/11
Clock Source
UART Rx
Timer 1
Timer 1
Timer 2
Timer 2
Timer 1
Timer 2
BRG
BRG
BRG