In IrDA mode, a 0 causes a low (or high) pulse for a configurable bit time (1/16, 1/8, 3/16, or 1/4). A 1 does not cause a pulse. The Smartcard support consists of the ability to capture or send a Smartcard ACK or NACK response during the stop bit periods.
Neither of these modes require the synchronous capability of the USART modules. As a result, all of the USART and UART modules have both IrDA and Smartcard support.