25.3.4.11 IRCOM Mode of Operation

The USART peripheral can be configured in Infrared Communication mode (IRCOM), which is IrDA® 1.4 compatible with baud rates up to 115.2 kbps. When enabled, the IRCOM mode enables infrared pulse encoding/decoding for the USART.

Figure 25-24. Block Diagram

The USART is set in IRCOM mode by writing a ‘1’ to the ENC bit in the Control G (USARTn.CTRLG) register. The data on the TXD/RXD pins are the inverted values of the transmitted/received infrared pulse. An event input can be used in place of the RX pin, allowing IRCOM to receive input from I/O pins or other sources instead of the corresonding RXD pin, which will disable the RxD input from the USART pin.

For transmission, three pulse modulation schemes are available:

3/16 of the baud rate period
Fixed programmable pulse time based on the peripheral clock frequency
Pulse modulation disabled

For the reception, a fixed programmable minimum high-level pulse-width for the pulse to be decoded as a logical ‘0’ is used. Shorter pulses will then be discarded, and the bit will be decoded to logical ‘1’ as if no pulse was received.

Double-Speed mode cannot be used for the USART when IRCOM mode is enabled.