C509-L_97 SIEMENS [Siemens Semiconductor Group], C509-L_97 Datasheet - Page 163

• Manufacturer Part Number: C509-L_97
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

6.5.1.3
There are several possibilities to generate the baud rate clock for the serial interface 0 depending
on the mode in which it is operated.
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 abbreviation f
The baud rate of the serial channel 0 is controlled by several bits which are located in the special
function registers as shown below.
Special Function Register ADCON0 (Address D8 H )
Special Function Register PCON (Address 87 H )
Special Function Register PRSC (Address B4 H )
Bit
BD
SMOD
S0P
Semiconductor Group
Bit No.
D8 H
B4 H
87 H
Baud Rates of Serial Channel 0
The shaded bits are not used in controlling serial interface 0
SMOD
WDTP
MSB
DF H
BD
Function
Baud rate generator enable
When set, the baud rate of serial interface 0 is derived from a dedicated baud rate
generator. When cleared (default after reset), baud rate is derived from the timer
1 overflow rate.
Double baud rate
When set, the baud rate of serial interface 0 in modes 1, 2, 3 is doubled. After
reset this bit is cleared.
Serial interface 0 prescaler
When set (default after reset), an additional prescaler by 2 is active at the
dedicated baud rate generator.
7
7
PDS
S0P
CLK
DE H
6
OSC
6
refers to the oscillator frequency (crystal or external clock operation).
ADEX
T2P1
IDLS
DD H
5
5
T2P0
BSY
DC H
SD
4
4
6-85
T1P1
ADM
GF1
DB H
3
3
On-Chip Peripheral Components
T1P2
GF0
MX2
DA H
2
2
.
T0P1
PDE
MX1
D9 H
1
1
Reset Value : 11010101 B
T0P0
IDLE
LSB
MX0
D8 H
0
0
Reset Value : 00 H
Reset Value : 00 H
PCON
PRSC
ADCON0
1997-10-01
C509-L