SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
There are 2 ways to stop a CIR reception:
There is a limitation when receiving data in UART CIR mode. Certain IrDA transceivers on the market have a characteristic that causes shrinking of the received modulation pulse hold-time. The UART receive filtering schema is based on the same encoding mechanism used for transmission.
For the following scenario:
Data sent with these conditions would contains 7μs pulses within a 28μs period. The UART expects to receive similar incoming data on receive, but various transceiver timing characteristics typically only send 2μs modulated pulses. These 2μs pulses will be filtered out and RX FIFO will not receive data. This does not affect UART CIR mode in transmission.
CIR RX demodulation can be bypassed by setting the UART_MDR3[0] DISABLE_CIR_RX_DEMOD bit.