Datasheet

Section 15 Serial Communication Interface (SCI, IrDA)
Rev. 4.00 Jun 06, 2006 page 447 of 1004
REJ09B0301-0400
15.3.5 IrDA Operation
Figure 15.21 shows a block diagram of the IrDA function.
When the IrDA function is enabled with bit IrE in KBCOMP, the SCI channel 2 TxD2 and RxD2
signals are subjected to waveform encoding/decoding conforming to IrDA specification version
1.0 (IrTxD and IrRxD pins). By connecting these pins to an infrared transceiver/receiver, it is
possible to implement infrared transmission/reception conforming to the IrDA specification
version 1.0 system.
In the IrDA specification version 1.0 system, communication is started at a transfer rate of 9600
bps, and subsequently the transfer rate can be varied as necessary. As the IrDA interface in the
H8S/2138 Group and H8S/2134 Group does not include a function for varying the transfer rate
automatically, the transfer rate setting must be changed by software.
IrDA
Pulse encoder
Pulse decoder
KBCOMP
TxD2/IrTxD
RxD2/IrRxD
SCI2
TxD
RxD
Figure 15.21 Block Diagram of IrDA Function
Transmission: In transmission, the output signal (UART frame) from the SCI is converted to an
IR frame by the IrDA interface (see figure 15.22).
When the serial data is 0, a high-level pulses of 3/16 the bit rate (interval equivalent to the width
of one bit) is output (initial value). The high-level pulse can be varied according to the setting of
bits IrCKS2 to IrCKS0 in KBCOMP.