XR17D154IV Exar Corporation, XR17D154IV Datasheet - Page 39

• Manufacturer Part Number: XR17D154IV
• Description: Universal QUART W/ PCI Bus Interface.
• Manufacturer: Exar Corporation

Specifications of XR17D154IV

• Features: *
• Number Of Channels: 4, QUART
• Fifo's: 64 Byte
• Protocol: RS485
• Voltage - Supply: 3.3V, 5V
• With Auto Flow Control: Yes
• With Irda Encoder/decoder: Yes
• With False Start Bit Detection: Yes
• With Modem Control: Yes
• Mounting Type: Surface Mount
• Package / Case: 144-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS Compliant

xr
REV. 1.2.2
Interrupt Generation:
• LSR is by any of the LSR bits 1, 2, 3 and 4.
• RXRDY is by RX trigger level.
• RXRDY Time-out is by the a 4-char plus 12 bits delay timer if the RX FIFO level is less than the RX trigger
• TXRDY is by LSR bit-5 (or bit-6 in auto RS485 control).
• MSR is by any of the MSR bits, 0, 1, 2 and 3.
• Receive Xon/Xoff/Special character is by detection of a Xon, Xoff or Special character.
• CTS#/DSR# is by a change of state on the input pin (from LOW to HIGH) with auto flow control enabled,
• RTS#/DTR# is when its receiver changes the state of the output pin (from LOW to HIGH) during auto RTS/
• Wake-up Indicator: when the UART comes out of sleep mode.
Interrupt Clearing:
• LSR interrupt is cleared by a read to the LSR register.
• RXRDY is cleared by reading data until FIFO falls below the trigger level.
• RXRDY Time-out is cleared by reading data until the RX FIFO is empty.
• TXRDY interrupt is cleared by a read to the ISR register.
• MSR interrupt is cleared by a read to the MSR register.
• Xon or Xoff character interrupt is cleared by a read to ISR register.
• Special character interrupt is cleared by a read to ISR register or after the next character is received.
• RTS#/DTR# and CTS#/DSR# status change interrupts are cleared by a read to the MSR register.
• Wake-up Indicator is cleared by a read to the INT0 register.
]
ISR[0]: Interrupt Status
•
•
ISR[3:1]: Interrupt Status
These bits indicate the source for a pending interrupt at interrupt priority levels 1, 2, 3 and 4 (See Interrupt
Source
P
level.
EFR bit-7, and depending on selection of MCR bit-2.
DTR flow control enabled by EFR bit-6 and selection of MCR bit-2.
Logic 0 = An interrupt is pending and the ISR contents may be used as a pointer to the appropriate interrupt
service routine.
Logic 1 = No interrupt pending (default condition).
RIORITY
L
EVEL
1
2
3
4
5
6
7
X
Table 14
B
IT
0
0
0
0
0
0
1
0
-5
).
B
IT
0
0
0
0
0
1
0
0
-4
ISR R
B
T
EGISTER
IT
0
0
1
0
0
0
0
0
ABLE
-3
14: I
B
S
IT
TATUS
1
1
1
0
0
0
0
0
-2
NTERRUPT
B
B
ITS
IT
1
0
0
1
0
0
0
0
-1
S
OURCE AND
39
B
UNIVERSAL (3.3V AND 5V) PCI BUS QUAD UART
IT
0
0
0
0
0
0
0
1
-0
LSR (Receiver Line Status Register)
RXRDY (Received Data Ready)
RXRDY (Receive Data Time-out)
TXRDY (Transmitter Holding Register Empty)
MSR (Modem Status Register)
RXRDY (Received Xon/Xoff or Special character)
CTS#/DSR#, RTS#/DTR# change of state
None (default)
P
RIORITY
L
S
EVEL
OURCE OF THE INTERRUPT
XR17D154