AT89C51CC03C-RLTIM View Datasheet(PDF) - Atmel Corporation

Part Name

Description

MFG CO.

AT89C51CC03C-RLTIM

Enhanced 8-bit MCU with CAN Controller and Flash Memory

Atmel Corporation 

Automatic Address

Recognition

valid stop bits cannot clear the FE bit. When the FE feature is enabled, RI rises on the

stop bit instead of the last data bit (See Figure 33. and Figure 34.).

Figure 33. UART Timing in Mode 1

RXD

RI

SMOD0=X

FE

SMOD0=1

D0 D1 D2 D3 D4 D5 D6 D7

Start

bit

Data byte

Stop

bit

Figure 34. UART Timing in Modes 2 and 3

RXD

D0 D1 D2 D3 D4 D5 D6 D7 D8

RI

SMOD0=0

Start

bit

Data byte

Ninth Stop

bit bit

RI

SMOD0=1

FE

SMOD0=1

The automatic address recognition feature is enabled when the multiprocessor commu-

nication feature is enabled (SM2 bit in SCON register is set).

Implemented in the hardware, automatic address recognition enhances the multiproces-

sor communication feature by allowing the serial port to examine the address of each

incoming command frame. Only when the serial port recognizes its own address will the

receiver set the RI bit in the SCON register to generate an interrupt. This ensures that

the CPU is not interrupted by command frames addressed to other devices.

If necessary, you can enable the automatic address recognition feature in mode 1. In

this configuration, the stop bit takes the place of the ninth data bit. Bit RI is set only when

the received command frame address matches the device’s address and is terminated

by a valid stop bit.

To support automatic address recognition, a device is identified by a given address and

a broadcast address.

Note: The multiprocessor communication and automatic address recognition features cannot

be enabled in mode 0 (i.e. setting SM2 bit in SCON register in mode 0 has no effect).

64 AT89C51CC03

4182K–CAN–05/06

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