AT89LP52 Atmel Corporation, AT89LP52 Datasheet - Page 61

• Manufacturer Part Number: AT89LP52
• Manufacturer: Atmel Corporation

Specifications of AT89LP52

• Flash (kbytes): 8 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

14.3
14.4
3709D–MICRO–12/11
Framing Error Detection
Automatic Address Recognition
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
137.5
19.2K
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
AT89LP51/52
)
]
Reload Value
FFDCH
FDC0H
FFDCH
FEE0H
EAB8H
FFEEH
FEE0H
FFFFH
FFB8H
FF70H
F2AFH
E55EH
FFB8H
FF70H
F55CH
F2AFH
61