C868 Datasheet, PDF (40/82 Pages) Infineon Technologies AG – 8-Bit Single-Chip Microcontroller

C868
Serial Interface (UART)
The serial port is a full duplex port capable of simultaneous transmit and receive
functions. It is also receive-buffered; it can commence reception of a second byte before
a previously-received byte has been read from the receive register. The serial port can
operate in 3 modes as illustrated in Table 10.
Table 10 UART Operating Modes
Mode
0
1
SCON
SM1
0
0
SM0
0
1
2
1
0
3
1
1
Description
Reserved
8-bit UART, variable baudrate
10 bits are transmitted (through TxD) or received (RxD)
9-bit UART, fixed baudrate
11 bits are transmitted (through TxD) or received (RxD)
9-bit UART, variable baudrate
Similar to mode 2, except for the variable baudrate.
For clarification, some terms regarding the difference between “baudrate clock“ and
“baudrate“ should be mentioned.
The serial interface requires a clock rate which is 16 times the baudrate for internal
synchronization. Therefore, the baudrate generators must provide a “baudrate clock“ to
the serial interface which divides it by 16, thereby resulting in the actual “baudrate“.
Data Sheet
40
V 1.0, 2003-05