C868_02 Datasheet, PDF (148/244 Pages) Infineon Technologies AG – 8 - Bit CMOS Microcontroller

C868
On-Chip Peripheral Components
The baud rate of the serial port is controlled by a bit which are located in the special
function registers as shown below.
PCON
Power Control Register
[Reset value: 0XXX0000_B]
7
6
5
4
3
2
1
0
SMOD
-
rw
r
-
SD
GF1
GF0
PDE
IDLE
r
rw
rw
rw
rw
rw
The functions of the shaded bits are not described here
Field
SMOD
Bits Typ Description
7
rw Double baud rate
When set, the baud rate of serial interface in modes
1, 2, 3 is doubled. After reset this bit is cleared.
Depending on the programmed operating mode different paths are selected for the baud
rate clock generation.
4.9.1.1 Baud Rate in Mode 2
The baud rate in mode 2 depends on the value of bit SMOD in special function register
PCON. If SMOD = 0 (which is the value after reset), the baud rate is 1/64 of the system
frequency. If SMOD = 1, the baud rate is 1/32 of the system frequency.
2 ^SMOD
Mode 2 baud rate =
x system frequency
64
4.9.1.2 Baud Rate in Mode 1 and 3
In these modes the baud rate is variable and can be generated alternatively by a baud
rate generator or by timer 1.
Using the Timer 2 as Baud Rate Generator
In modes 1 and 3, the C868 can use timer 2 as the baud rate generator for the serial port.
To enable the baud generator for transmit, bit TCLK (bit 4 of special function register
User’s Manual
4-104
V 0.4, 2002-01