I've noticed that IrDA as part of LPUART module is not supported in SDK API(version 2.7) and there is no examples or explanation. Could you please clarify if there is a plan to add this to SDK?
I took lpuart_interrupt example for rt1015evk board, changed uart module to lpuart3, and briefly tried to connect simple Ir receiver (from arduino kit - CHQ1838) to J30 RX pin. I set IREN bit manually, but unfortunately, I can receive only 0xff bytes. It looks like a problem with baud rate and I changed the baud rate from 115200 to 38000(also tested with 38400), but the same result.
According to "Version ID Register" the MCU supports hardware IrDA decoding. So, I expect that it should work.
Please, take a look at the timing diagram from the Ir receiver. It would be good if you provide some reference examples.