AT89LP52-20AU Atmel, AT89LP52-20AU Datasheet - Page 60

• Manufacturer Part Number: AT89LP52-20AU
• Description: IC MCU 8051 8K FLASH SPI 44TQFP
• Manufacturer: Atmel
• Series: 89LPr

Specifications of AT89LP52-20AU

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 36
• Program Memory Size: 8KB (8K 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: 44-TQFP
• Processor Series: AT89x
• Core: 8051
• Data Bus Width: 8 bit
• Data Ram Size: 256 B
• Interface Type: Serial
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 36
• Number Of Timers: 3
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Details

14.3
14.4
60
Framing Error Detection
Automatic Address Recognition
AT89LP51/52 - Preliminary
is similar to the auto-reload mode, in that a rollover causes the Timer 2 registers to be reloaded
with the 16-bit value in registers RCAP2H and RCAP2L, which are preset by software. In this
case, the baud rates in Modes 1 and 3 are determined by Timer 2’s overflow rate according to
the following equation:
Table 14-3
Table 14-3.
In addition to all of its usual modes, the UART can perform framing error detection by looking for
missing stop bits, and automatic address recognition. When used for framing error detect, the
UART looks for missing stop bits in the communication. A missing bit will set the FE bit in the
SCON register. The FE bit shares the SCON.7 bit with SM0 and the function of SCON.7 is deter-
mined by PCON.6 (SMOD0). If SMOD0 is set then SCON.7 functions as FE. SCON.7 functions
as SM0 when SMOD0 is cleared. When used as FE, SCON.7 can only be cleared by software.
The FE bit will be set by a framing error regardless of the state of SMOD0.
Automatic Address Recognition is a feature which allows the UART to recognize certain
addresses in the serial bit stream by using hardware to make the comparisons. This feature
saves a great deal of software overhead by eliminating the need for the software to examine
every serial address which passes by the serial port. This feature is enabled by setting the SM2
bit in SCON for Modes 1, 2 or 3. In the 9-bit UART modes, Mode 2 and Mode 3, the Receive
Baud Rate
Max: 750K
19.2K
19.2K
137.5
137.5
9.6K
4.8K
2.4K
1.2K
9.6K
4.8K
2.4K
1.2K
110
110
110
lists commonly used baud rates and how they can be obtained from Timer 2.
Commonly Used Baud Rates Generated by Timer 2
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
Modes 1 and 3
12
12
12
Baud Rate
(MHz)
6
CDV
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
=
----- -
16
1
×
CP/RL2
-------------------------------------------------------------------------------- -
[
65536
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
System Frequency
–
(
C/T2
RCAP2H,RCAP2L
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TCLK or RCLK
Timer 2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
)
]
3709B–MICRO–12/10
Reload Value
FFDCH
FFDCH
FEE0H
FDC0H
EAB8H
FFEEH
FEE0H
FFFFH
FFB8H
F2AFH
E55EH
FFB8H
F55CH
F2AFH
FF70H
FF70H