HD64F2149 Datasheet, PDF (501/1035 Pages) Renesas Technology Corp – Hitachi 16-Bit Single-Chip Microcomputer

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/2169 or H8S/2149 does not include a function for varying the transfer rate automatically, the
transfer rate setting must be changed by software.
IrDA
SCI2
TxD2/IrTxD
TxD
Pulse encoder
RxD2/IrRxD
RxD
Pulse decoder
KBCOMP
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.
The high-level pulse width is fixed at a minimum of 1.41 µs, and a maximum of (3/16 + 2.5%) ×
bit rate or (3/16 × bit rate) + 1.08 µs.
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