Rainbow-electronics T89C51CC02 Manual de usuario descargar pdf (Pagina 45)

Rev.A - May 17, 2001 45

Preliminary

T89C51CC02

11. Serial I/O Port

The T89C51CC02 I/O serial port is compatible with the I/O serial port in the 80C52.

It provides both synchronous and asynchronous communication modes. It operates as a Universal Asynchronous

Receiver and Transmitter (UART) in three full-duplex modes (Modes 1, 2 and 3). Asynchronous transmission and

reception can occur simultaneously and at different baud rates

Serial I/O port includes the following enhancements:

• Framing error detection

• Automatic address recognition

Figure 25. Serial I/O Port Block Diagram

11.1. Framing Error Detection

Framing bit error detection is provided for the three asynchronous modes. To enable the framing bit error detection

feature, set SMOD0 bit in PCON register.

Figure 26. Framing Error Block Diagram

When this feature is enabled, the receiver checks each incoming data frame for a valid stop bit. An invalid stop

bit may result from noise on the serial lines or from simultaneous transmission by two CPUs. If a valid stop bit

is not found, the Framing Error bit (FE) in SCON register bit is set.

Write SBUF

SBUF

Transmitter

SBUF

Receiver

IB Bus

Mode 0 Transmit

Receive

Shift register

Load SBUF

Read SBUF

SCON

Interrupt Request

Serial Port

TXD

RXD

RITIRB8TB8RENSM2SM1SM0/FE

IDLPDGF0GF1POF-SMOD0SMOD1

To UART framing error control

SM0 to UART mode control

Set FE bit if stop bit is 0 (framing error)

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Rainbow-electronics T89C51CC02 Manual de usuario Pagina 45