SAB80C517-M16 SIEMENS [Siemens Semiconductor Group], SAB80C517-M16 Datasheet - Page 54

• Manufacturer Part Number: SAB80C517-M16
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Mode 0
The baud rate in mode 0 is fixed:
Mode 0 baud rate =
Mode 2
The baud rate in mode 2 depends on the value of bit SMOD in special function register PCON (see
figure 7-9). If SMOD = 0 (which is the value after reset), the baud rate is 1/64 of the oscillator
frequency. If SMOD = 1, the baud rate is 1/32 of the oscillator frequency.
Mode 2 baud rate =
Figure 7-9
Special Function Register PCON (Address 87 H )
Bit
SMOD
Modes 1 and 3
In these modes the baud rate is variable and can be generated alternatively by a dedicated baud
rate generator or by timer 1.
Using the baud rate generator:
In modes 1 and 3, the SAB 80C517 can use the internal baud rate generator for serial interface 0.
To enable this feature, bit BD (bit 7 of special function register ADCON0) must be set (see
figure 7-10). This baud rate generator divides the oscillator frequency by 2496. Bit SMOD
(PCON.7) also can be used to enable a multiply-by-two prescaler (see figure 7-9). At 12-MHz
oscillator frequency, the commonly used baud rates 4800 baud (SMOD = 0) and 9600 baud (SMOD
= 1) are available (with 0.16 % deviation). The baud rate is determined by SMOD and the oscillator
frequency as follows:
Semiconductor Group
87 H
SMOD
These bits are not used in controlling serial interface 0.
oscillator frequency
2
SMOD
64
PDS
Function
When set, the baud rate of serial interface 0 in modes 1, 2, 3 is doubled.
12
x
oscillator frequency
IDLS
SD
55
GF1
On-Chip Peripheral Components
GF0
PDE
IDLE
PCON