ZHCSKJ6 December 2019 TL16C750E
PRODUCTION DATA.
The IIR is a read-only 8-bit register, which provides the source of the interrupt in a prioritized manner. Table 20 shows interrupt identification register bit settings.
| BIT | BIT SETTINGS |
|---|---|
| 0 | 0 = An interrupt is pending
1 = No interrupt is pending |
| 3:1 | 3-Bit encoded interrupt. See Table 19 |
| 4 | 1 = Xoff or special character has been detected |
| 5 | CTS/RTS low to high change of state |
| 7:6 | Mirror the contents of FCR[0] |
The interrupt priority list is illustrated in Table 21.
| PRIORITY LEVEL | BIT 5 | BIT 4 | BIT 3 | BIT 2 | BIT 1 | BIT 0 | INTERRUPT SOURCE |
|---|---|---|---|---|---|---|---|
| 1 | 0 | 0 | 0 | 1 | 1 | 0 | Receiver line status error |
| 2 | 0 | 0 | 1 | 1 | 0 | 0 | Receiver timeout interrupt |
| 2 | 0 | 0 | 0 | 1 | 0 | 0 | RHR interrupt |
| 3 | 0 | 0 | 0 | 0 | 1 | 0 | THR interrupt |
| 4 | 0 | 0 | 1 | 0 | 0 | 0 | Modem interrupt |
| 5 | 0 | 1 | 0 | 0 | 0 | 0 | Received Xoff signal or special character |
| 6 | 1 | 0 | 0 | 0 | 0 | 0 | CTS, RTS change of state from active (low) to inactive (high) |