| Interrupt ID | Priority Level | Interrupt Type | Interrupt Source | Interrupt Reset
|
|---|
| 0001 | - | None | None | -
|
| 0110 | Highest | Receiver line status
| Overrun/parity/framing errors or break interrupt
| Reading the line status register
|
| 0011 | Second | RS485 Interrupt
| In RS485 mode, receives address data and match setting address
| Writes 1 to addr flag to reset
|
| 0100 | Third | Received data available
| Receiver data available (non-FIFO mode or FIFOs disabled) or RCVR FIFO trigger level
reached (FIFO mode and FIFOs enabled)
| Reading the receiver buffer register (non-FIFO mode or FIFOs disabled) or the FIFO
drops below the trigger level (FIFO mode and FIFOs enabled)
|
| 1100 | Fourth | Character timeout indication
| No characters in or out of the RCVR FIFO during the last 4 character times and there is at
least 1character in it during This time
| Reading the receiver buffer register
|
| 0010 | Fifth | Transmit holding register empty
| Transmitter holding register empty (Program THRE mode disabled) or XMIT FIFO at or
below threshold (Program THRE mode enabled)
| Reading the IIR register (if source of interrupt); or, writing into THR (FIFOs or
THRE mode not selected or disabled) or XMIT FIFO above threshold (FIFOs and THRE mode selected and enabled).
|
| 0000 | Sixth | Modem status
| Clear to send or data set ready or ring indicator or data carrier detect.
Note that if auto flow control mode is enabled, a change in CTS (that is, DCTS set) does not cause an interrupt.
| Reading the Modem status register
|
| 0111 | Seventh | Busy detect indication
| UART_16550_COMPATIBLE = NO and master has tried to write to the Line Control Register while the UART is busy (USR[0] is set to one).
| Reading the UART status register
|
