SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
After reset, the RX FIFO input is high and the 4-bit counter is cleared. When a rising edge is detected on RX, the RX FIFO input falls on the next rising edge of 16XCLK with sufficient setup time. The RX FIFO input stays low for 16 cycles (16XCLK) and then returns to high as required by the IrDA specification. As long as no pulses (rising edges) are detected on the RX, the RX FIFO input remains high.
Figure 24-43 shows the IrDA SIR decoding mechanism.
The module can transmit and receive data, but when the device is transmitting, the IR RX circuitry is automatically disabled by hardware. The operation of the uart3_rxd input can be disabled using the UART3.UART_ACREG[5] DIS_IR_RX bit. The UART3.UART_MDR2[6] IRRXINVERT bit can invert the signal from the transceiver (RXD) pin to the IR RX logic in the UART. This inversion is performed by default.