24.3.2.11.1 Overview

A USART can be configured in infrared communication mode (IRCOM) that is IrDA compatible with baud rates up to 115.2 kbps. When enabled, the IRCOM mode enables infrared pulse encoding/decoding for the USART.

A USART is set in IRCOM mode by writing 0x2 to the CMODE bits in USARTn.CTRLC. The data on the TX/RX pins is the inverted value of the transmitted/received infrared pulse. It is also possible to select an event channel from the Event System as an input for the IRCOM receiver. This will disable the RX 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.