UPSD3422_06 Datasheet, PDF (111/293 Pages) STMicroelectronics – Turbo Plus Series Fast Turbo 8032 MCU with USB and Programmable Logic

uPSD34xx
22 IrDA interface
IrDA interface
Note:
uPSD34xx 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 Figures 39 and 40.
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.
In Figure 40 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 39. IrDA interface
UART1
SIRClk
TxD
RxD
IrDA
Interf ac e
TxD1-IrDA
RxD1-IrDA
IrDA
Transceiver
uPSD34xx
AI10437
Figure 40. Pulse shaping by the IrDA interface
Start
Bit
UART Frame
Data Bits
Stop
Bit
0
1
0
1
0
0
1
1
0
1
Start
Bit
UART Frame
IR Frame
Data Bits
Stop
Bit
0
1
0
1
0
0
1
1
0
1
Bit Time
IR Frame
Pulse Width = 3/16 Bit Time
AI10438
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