C504 Datasheet, PDF (24/49 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

C504
Serial Interface (USART)
The serial port is full duplex and can operate in four modes (one synchronous mode, three
asynchronous modes) as illustrated in table 6. The possible baudrates can be calculated using the
formulas given in table 6.
Table 6
USART Operating Modes
Mode
0
1
2
3
SCON
SM0 SM1
0
0
0
1
1
0
1
1
Baudrate
Description
f_OSC/12
Timer 1/2 overflow rate
f_OSC/32 or f_OSC/64
Timer 1/2 overflow rate
Serial data enters and exits through R×D.
T×D outputs the shift clock. 8-bit are
transmitted/received (LSB first)
8-bit UART
10 bits are transmitted (through T×D) or
received (R×D)
9-bit UART
11 bits are transmitted (T×D) or
received (R×D)
9-bit UART
Like mode 2 except the variable baud rate
Figure 8
Block Diagram of Baud Rate Generation for the Serial Interface
Semiconductor Group
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