C868_02 Datasheet, PDF (147/244 Pages) Infineon Technologies AG – 8 - Bit CMOS Microcontroller

Field
SM0
SM1
C868
On-Chip Peripheral Components
Bits Typ Description
[7:6] rw Serial port 0 operating mode selection bits
Table 1 :
SM0
0
0
1
1
SM1
0
1
0
1
Selected operating mode
mode 0 :reserved
mode 1 :8-bit UART, variable baud
rate
mode 2 :9-bit UART, fixed baud
rate
(f_sys/32 or f_sys/64)
Mode 3 :9-bit UART, variable baud
rate
4.9.1 Baud Rate Generation
There are several possibilities to generate the baud rate clock for the serial port
depending on the mode in which it is operating.
For clarification, some terms regarding the difference between "baud rate clock" and
"baud rate" should be mentioned. The serial interface requires a clock rate which is 16
times the baud rate for internal synchronization. Therefore, the baud rate generators
have to provide a "baud rate clock" to the serial interface which - there divided by 16 -
results in the actual "baud rate". However, all formulas given in the following section
already include the factor and calculate the final baud rate. Further, the abrevation f_SYS
refers to the system frequency.
User’s Manual
4-103
V 0.4, 2002-01