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M0A21/M0A23 Series
May 06, 2022
Page
434
of 746
Rev 1.02
M0
A21
/M
0
A
2
3
SE
RIES
TEC
H
NICAL
RE
FEREN
C
E
M
ANUAL
Baud Rate = Clock / (16 * (BRD +2))
, where BRD (UART_BAUD[15:0]) is Baud Rate Divider in
UART_BAUD register.
Note:
The tolerance of baud-rate is ±5% between IrDA master and IrDA slave.
The IrDA control block diagram is shown in Figure 6.11-15.
IrDA
SIR
IR_ SOUT
IR_SIN
SOUT
UART
Controller
TX
RX
SIN
IrDA
Control Register
IrDA Function
Enable
APB Bus
IrDA Transmitter
IrDA Receiver
TXEN
TXINV
RXINV
UART_TXD
UART_RXD
Figure 6.11-15 IrDA Control Block Diagram
IrDA SIR Transmit Encoder
The IrDA SIR Transmit Encoder modulates Non-Return-to-Zero (NRZ) transmit bit stream output from
UART. The IrDA SIR physical layer specifies the use of Return-to-Zero, Inverted (RZI) modulation
scheme which represents logic 0 as an infra light pulse. The modulated output pulse stream is
transmitted to an external output driver and infrared light emitting diode.
The transmitted pulse width is specified as 3/16 period of baud rate.
IrDA SIR Receive Decoder
The IrDA SIR Receive Decoder demodulates the Return-to-Zero bit stream from the input detector and
outputs the NRZ serial bits stream to the UART received data input.
In idle state, the decoder input is high. A start bit is detected when the decoder input is LOW. In normal
operation, the RXINV (UART_IRDA[6]) is set to ‘1’ and TXINV (UART_IRDA[5]) is set to ‘0’.
IrDA SIR Operation
The IrDA SIR encoder/decoder provides functionality which converts between UART data stream and
half-duplex serial SIR interface. Figure 6.11-16 is IrDA encoder/decoder waveform.