w79e532 Winbond Electronics Corp America, w79e532 Datasheet - Page 54

• Manufacturer Part Number: w79e532
• Description: 8-bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

Table 10. Serial Ports Modes
12.1 Framing Error Detection
A Frame Error occurs when a valid stop bit is not detected. This could indicate incorrect serial data
communication. Typically the frame error is due to noise and contention on the serial communication
line. The W79E(L)532 has the facility to detect such framing errors and set a flag which can be
checked by software.
The Frame Error FE(FE_1) bit is located in SCON.7. This bit is normally used as SM0 in the standard
8051 family. However, in the W79E(L)532 it serves a dual function and is called SM0/FE. There are
actually two separate flags, one for SM0 and the other for FE. The flag that is actually accessed as
SCON.7 is determined by SMOD0 (PCON.6) bit. When SMOD0 is set to 1, then the FE flag is
indicated in SM0/FE. When SMOD0 is set to 0, then the SM0 flag is indicated in SM0/FE.
The FE bit is set to 1 by hardware but must be cleared by software. Note that SMOD0 must be 1 while
reading or writing to FE. If FE is set, then any following frames received without any error will not clear
the FE flag. The clearing has to be done by software.
SM1
0
0
1
1
(SMOD_1)
SMOD=
Overflow
RCLK
TCLK
Timer 1
SM0
RXD
0
1
0
1
2
0
SAMPLE
0
0
1
MODE
(for Serial Port 0 only)
0
1
2
3
1
1
DETECTOR
Timer 2 Overflow
1-TO-0
16
16
Asynch.
Asynch.
Asynch.
Synch.
TYPE
Write to
SBUF
START
TX CLOCK
RX CLOCK
TX START
CONTROLLER
DETECTOR
RX
Figure 23. Serial Port Mode 3
4 or 12 T
Timer 1 or 2
32 or 64
Timer 1 or 2
SERIAL
BIT
BAUD CLOCK
Data Bus
RX SHIFT
TX SHIFT
Internal
LOAD
SBUF
T
CLKS
- 54 -
CLKS
TI
RI
TB8
Receive Shift Register
CLOCK
SIN
FRAME
11 bits
11 bits
10 bits
8 bits
SIZE
PAROUT
Transmit Shift Register
STOP
LOAD
CLOCK
START
PARIN
D8
D8
W79E532/W79L532
SOUT
STAR
T BIT
No
SBUF
RB8
1
1
1
STOP
BIT
No
Serial Port
SBUF
1
1
1
Interrupt
Read
TXD
FUNCTION
9TH BIT
Internal
None
None
Data
0, 1
0, 1
Bus