AT89LP4052-20XU Atmel, AT89LP4052-20XU Datasheet - Page 33

• Manufacturer Part Number: AT89LP4052-20XU
• Description: IC 8051 MCU FLASH 4K 20TSSOP
• Manufacturer: Atmel
• Series: 89LPr

Specifications of AT89LP4052-20XU

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 15
• Program Memory Size: 4KB (4K x 8)
• Program Memory Type: FLASH
• Ram Size: 256 x 8
• Voltage - Supply (vcc/vdd): 2.4 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 20-TSSOP
• Processor Series: AT89x
• Core: 8051
• Data Bus Width: 8 bit
• Data Ram Size: 256 B
• Interface Type: UART, SPI
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 15
• Number Of Timers: 2
• Operating Supply Voltage: 2.4 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: AT89ISP
• Minimum Operating Temperature: - 40 C
• Package: 20TSSOP
• Device Core: 8051
• Family Name: AT89
• Maximum Speed: 20 MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Details

18.2
18.2.1
3547J–MICRO–10/09
Baud Rates
Using Timer 1 to Generate Baud Rates
The baud rate in Mode 0 is fixed as shown in the following equation.
The baud rate in Mode 2 depends on the value of the SMOD1 bit in Special Function Register
PCON.7. If SMOD1 = 0 (the value on reset), the baud rate is 1/32 of the oscillator frequency. If
SMOD1 = 1, the baud rate is 1/16 of the oscillator frequency, as shown in the following equation.
The Timer 1 overflow rate 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.
Programmers can achieve very low baud rates with Timer 1 by configuring the Timer to run as a
16-bit auto-reload timer (high nibble of TMOD = 0001B). In this case, the baud rate is given by
the following formula.
Mode 2 Baud Rate
Modes 1, 3
Baud Rate
Modes 1, 3
Baud Rate
Modes 1, 3
Baud Rate
Mode 0 Baud Rate
=
=
=
2
------------------- -
SMOD1
2
------------------- -
2
------------------- -
32
SMOD1
=
SMOD1
32
32
2
------------------- -
SMOD1
32
×
=
×
×
(Timer 1 Overflow Rate)
Oscillator Frequency
------------------------------------------------------ -
-------------------------------------------------------- -
[
Oscillator Frequency
------------------------------------------------------ -
Oscillator Frequency
65536
×
[
(Oscillator Frequency)
256
AT89LP2052/LP4052
–
2
–
(
RH1,RL1
(
TH1
)
]
)
]
33