Philips Semiconductors

Product specification

80CL31/80CL51

Low-voltage single-chip 8-bit microcontrollers

January 1995

13

SM2

Enables the multiprocessor communication feature in Modes 2 and 3. In Mode 2 or 3, if SM2 is set to 1 then Rl will not

be activated if the received 9th data bit (RB8) is 0. In Mode 1, if SM2=1 then R1 will not be activated if a valid stopbit

was not received. In Mode 0, SM2 should be 0.

REN

Enables serial reception. Set by software to enable reception. Clear by software to disable reception.

TB8

Is the 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as desired.

RB8

In Modes 2 and 3, is the 9th data bit that was received. In Mode 1, it SM2=0, RB8 is the stop bit that was received. In

Mode 0, RB8 is not used.

TI

Is transmit interrupt flag. Set by hardware at the end of the 8th time in Mode 0, or at the beginning of the stop bit in the

other modes, in any serial transmission. Must be cleared by software.

RI

Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or halfway through the stop bit time in

the other modes, in any serial reception except (see SM2). Must be cleared by software.

MSB

LSB

SM0

SM1

SM2

REN

TB8

RB8

T1

R1

Where SM0, SM1 specify the serial port mode, as follows:

SM0

SM1

Mode

Description

Baud Rate

0

0

0

shift register

0

1

1

8-bit UART

variable

1

0

2

9-bit UART

or

1

1

3

9-bit variable UART

Figure 6. Serial Port control (SCON) Register

Table 2.

Timer 1 Generated Commonly Used Baud Rates

TIMER 1

BAUD RATE

SMOD

C/T

MODE

RELOAD VALUE

Mode 0 Max: 1.33 Mb/s

16 MHz

x

x

x

x

Mode 2 Max: 500 Kb/s

16 MHz

1

x

x

x

Modes 1,3: 83.3 Kb/s

16 MHz

1

0

2

FFH

19.2 Kb/s

11.059 MHz

1

0

2

FDH

9.6 Kb/s

11.059 MHz

0

0

2

FDH

4.8 Kb/s

11.059 MHz

0

0

2

FAH

2.4 Kb/s

11.059 MHz

0

0

2

F4H

1.2 Kb/s

11.059 MHz

0

0

2

E8H

137.5 Kb/s

11.986 MHz

0

0

2

1DH

110

6 MHz

0

0

2

72H

110

12 MHz

0

0

1

FEEBH