Q67121-C1068 View Datasheet(PDF) - Infineon Technologies

Part Name

Description

Manufacturer

Q67121-C1068

8-Bit CMOS Microcontroller

Infineon Technologies 

C515A

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 5. The possible baudrates can be calculated using the

formulas given in table 5.

Table 5

USART Operating Modes

Mode

0

1

2

3

SCON

SM0

SM1

0

0

0

1

1

0

1

1

Description

Shift register mode

Serial data enters and exits through R×D/ T×D outputs the shift

clock; 8-bit are transmitted/received (LSB first); fixed baud rate

8-bit UART, variable baud rate

10 bits are transmitted (through T×D) or received (at R×D)

9-bit UART, fixed baud rate

11 bits are transmitted (through T×D) or received (at R×D)

9-bit UART, variable baud rate

Like mode 2

For clarification some terms regarding the difference between “baud rate clock” and “baud rate”

should be mentioned. In the asynchronous modes the serial interfaces require a clock rate which is

16 times the baud rate for internal synchronization. Therefore, the baud rate generators/timers have

to provide a “baud rate clock” (output signal in figure 13 to the serial interface which - there divided

by 16 - results in the actual “baud rate”. Further, the abbreviation fOSC refers to the oscillator

frequency (crystal or external clock operation).

The variable baud rates for modes 1 and 3 of the serial interface can be derived from either timer 1

or a dedicated baud rate generator (see figure 13).

Semiconductor Group

29

1997-10-01

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