XR17D154 Exar Corporation, XR17D154 Datasheet - Page 16

• Manufacturer Part Number: XR17D154
• Description: Four-channel Pci-bus Uart
• Manufacturer: Exar Corporation

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PRELIMINARY
A 16-bit down-count timer for general purpose timer or counter. Its clock source may be selected from internal
crystal oscillator or externally on pin TMRCK. The timer can be set to be a single-shot for a one-time event or
re-triggerable for continue interval. An interrupt may be generated in the INT Register when the timer times out.
It is controlled through 4 configuration registers [TIMERCNTL, TIMER, TIMELSB, TIMERMSB]. These
registers provide start/stop and re-triggerable or one-shot operation. The time-out output of the Timer can be
set to generate an interrupt for system or event alarm.
RXRDY is clear by reading data in the RX FIFO until it falls below the trigger level.
RXRDY Time-out interrupt is cleared when the RX FIFO becomes empty.
RX Line Status interrupt clears after reading the LSR register.
TXRDY interrupt clears after reading ISR register that is in the UART channel register set.
Modem Status Register interrupt clears after reading MSR register that is in the UART channel register set.
RTS/CTS or DTR/DSR delta interrupt clears after reading MSR register that is in the UART channel register set.
Xoff/Xon delta and special character detect interrupt clears after reading the ISR register in the UART channel register set.
TIMER Time-out interrupt clears after reading the TIMERCNTL register that is in the Device Configuration register set.
MPIO interrupt clears after reading the MPIOLVL register that is in the Device Configuration register set.
TIMERCNTL [0]
TIMERCNLT [1]
TIMERCNTL [2]
TIMERCNTL [3]
TIMERCNTL [4]
TIMERCNTL [7:5]
2.2.2
F
IGURE
General Purpose 16-bit Timer/Counter [TIMERMSB, TIMELSB, TIMER, TIMECNTL] (
0
X
XX-XX-00-00)
7. T
T IM E R C N T L [3 ]
T IM E R C N T L [1 ]
T IM E R C N T L [2 ]
T IM E R C N T L [0 ]
T IM E R C N T L [4 ]
T IM E R M S B a n d T IM E R L S B
O S C . C L O C K
IMER
Logic zero (default) disables Timer-Counter interrupt and logic one enables the interrupt, reading the
TIMERCNTL clears the interrupt.
Logic zero (default) stops/pauses the timer and logic one starts/re-starts the timer/counter.
Logic zero (default) selects re-trigger timer function and logic one selects one-shot (timer function.
Logic zero (default) selects internal and logic one selects external clock to the timer/counter.
Routes the Timer-Counter interrupt to MPIO[0] if MPIOSEL[0]=0 for external event control.
Reserved (defaults to zero)
T M R C K
(1 6 -b it V a lu e )
/C
OUNTER CIRCUIT
T
T im e r In te rru p t E n a b le
S ta rt/S to p
S in g le /R e -trig g e ra b le
C lo ck
S e le ct
ABLE
1
0
6: UART C
T
ABLE
.
7: TIMER CONTROL R
T im er/C ou n te r
HANNEL
1 6 -B it
R e -trig g e r
16
[3:0] I
0
1
UNIVERSAL (3.3V AND 5V) PCI BUS QUAD UART
T im e -o u t
S in g le -sh o t
NTERRUPT
EGISTERS
1
0
N o In te rru p t
C
T im er In te rru p t, C h-0 IN T = 7
LEARING
1
0
:
M P IO LV L [0 ]
M P IO [0 ]
XR17D154
REV. P1.0.0
DEFAULT