C517A Datasheet, PDF (42/72 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

C517A
Table 10 below lists the values/formulas for the baud rate calculation of serial interface 0 and 1 with
its dependencies of the control bits BD and SMOD.
Table 10
Serial Interfaces - Baud Rate Dependencies
Serial Interface
Operating Modes
Mode 0 (Shift Register)
Mode 1 (8-bit UART)
Mode 3 (9-bit UART)
Mode 2 (9-bit UART)
Mode A (9-bit UART)
Mode B (8-bit UART)
Active Control
Bits
SMOD BD
–
–
X
0
1
X
–
–
–
Baud Rates
Fixed baud rate clock fosc/12
Timer 1 overflow is used for baud rate
generation; SMOD controls a divide-by-2 option.
Baud rate = 2^SMOD x timer 1 overflow rate / 32
Baud rate generator is used for baud rate
generation; SMOD controls a divide-by-2 option
Baud rate = 2^SMOD x oscillator frequency /
64 x (baud rate gen. overflow rate)
Fixed baud rate clock fosc/32 (SMOD=1) or fosc/
64 (SMOD=0)
Baud rate generator is used for baud rate
generation; SMOD controls a divide-by-2 option
Baud rate = oscillator frequency /
32 x (baud rate gen. overflow rate)
Semiconductor Group
40