UPSD3312D datasheet(119/272 Pages) STMICROELECTRONICS

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UPSD33xx

IrDA interface

Doc ID 9685 Rev 7

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IrDA interface

UPSD33xx devices provide an internal IrDA interface that will allow the connection of the

UART1 serial interface directly to an external infrared transceiver device. The IrDA interface

does this by automatically shortening the pulses transmitted on UART1’s TxD1 pin, and

stretching the incoming pulses received on the RxD1 pin. Reference Figure 35 and

Figure 36.

When the IrDA interface is enabled, the output signal from UART1’s transmitter logic on pin

TxD1 is compliant with the IrDA Physical Layer Link Specification v1.4 (www.irda.org)

operating from 1.2k bps up to 115.2k bps. The pulses received on the RxD1 pin are

stretched by the IrDA interface to be recognized by UART1’s receiver logic, also adhering to

the IrDA specification up to 115.2k bps.

Note:

In Figure 36 a logic '0' in the serial data stream of a UART Frame corresponds to a logic high

pulse in an IR Frame. A logic '1' in a UART Frame corresponds to no pulse in an IR Frame.

Figure 35.

IrDA interface

UART1

IrDA

Interface

TxD

RxD

UPSD33XX

IrDA

Transceiver

TxD1-IrDA

RxD1-IrDA

SIRClk

AI07851b

UPSD3312D Datasheet(PDF) 119 Page - STMicroelectronics