TS80C31X2
6.3 TS80C31X2 Serial I/O Port
The serial I/O port in the TS80C31X2 is compatible with the serial I/O port in the 80C31.
It provides both synchronous and asynchronous communication modes. It operates as an Universal Asynchronous
Receiver and Transmitter (UART) in three full-duplex modes (Modes 1, 2 and 3). Asynchronous transmission and
reception can occur simultaneously and at different baud rates
Serial I/O port includes the following enhancements:
● Framing error detection
● Automatic address recognition
6.3.1 Framing Error Detection
Framing bit error detection is provided for the three asynchronous modes (modes 1, 2 and 3). To enable the framing
bit error detection feature, set SMOD0 bit in PCON register (See Figure 4).
SM0/FE SM1
SM2
REN
TB8
RB8
TI
RI
SCON (98h)
Set FE bit if stop bit is 0 (framing error) (SMOD = 1)
SM0 to UART mode control (SMOD = 0)
PCON (87h)
SMOD1SMOD0
-
POF
GF1
GF0
PD
IDL
To UART framing error control
Figure 4. Framing Error Block Diagram
When this feature is enabled, the receiver checks each incoming data frame for a valid stop bit. An invalid stop
bit may result from noise on the serial lines or from simultaneous transmission by two CPUs. If a valid stop bit
is not found, the Framing Error bit (FE) in SCON register (See Table 5.) bit is set.
12
Rev. A - Mar. 19, 1999
Preliminary
TEMIC [ TEMIC SEMICONDUCTORS ]
