SAB80515 Datasheet, PDF (49/270 Pages) Siemens Semiconductor Group – 8-Bit Single-Chip Microcontroller Family

On-Chip Peripheral Components
The control and status bits of the serial channel in special function register SCON are illustrated in
figure 7-8. Figure 7-7 shows the special function register SBUF which is the data register for
receive and transmit. The following table summarizes the operating modes of the serial interface.
Table 7-3
Serial Interface, Mode Selection
SM0
0
0
1
1
SM1
0
1
0
1
Mode
0
1
2
3
Descriptions
Shift register
8-bit UART
9-bit UART
9-bit UART
Baud Rate
f_OSC/12
Variable
f_OSC/64 or f_OSC/32
Variable
Figure 7-8
Special Function Register SBUF (Address 99H)
99H
Serial interface buffer register
SBUF
Receive and transmit buffer of serial interface. Writing to SBUF loads the transmit register and
initiates transmission. Reading out SBUF accesses a physically separate receive register.
Semiconductor Group
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