C517A_99 Datasheet, PDF (140/218 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C517A
Timer 1 Overflow
f _OSC /2
Baud
Rate
Generator
(S0RELH
S0RELL)
ADCON0.7
(BD)
0
1
Mode 1
Mode 3
Mode 2
S0CON.7
S0CON.6
(SM0/
SM1)
Mode 0
PCON.7
(SMOD)
÷2
0
1
Only one mode
÷6
can be selected
Note : The switch configuration shows the reset state.
Baud
Rate
Clock
MCS03329
Figure 6-33
Baud Rate Generation for Serial Channel 0
Depending on the programmed operating mode different paths are selected for the baud rate clock
generation. Table 6-12 shows the dependencies of the serial port 0 baud rate clock generation from
the 3 control bits and from the mode which is selected in the special function register S0CON.
Table 6-12
Serial Interface 0 - Baud Rate Dependencies
Serial Interface 0
Operating Modes
Mode 0 (Shift Register)
Mode 1 (8-bit UART)
Mode 3 (9-bit UART)
Mode 2 (9-bit UART)
Active Control Bits Baud Rate Clock Generation
BD
SMOD
–
–
Fixed baud rate clock fosc/12
X
X
BD=0 : Timer 1 overflow is used for baud rate
generation; SMOD controls a divide-by-
2 option.
BD=1 : Baud rate generator is used for baud
rate generation; SMOD controls a
divide-by-2 option .
–
X
Fixed baud rate clock fosc/32 (SMOD=1) or
fosc/64 (SMOD=0)
Semiconductor Group
6-74