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參數資料
| 型號： | XR16C854 |
| 廠商： | Exar Corporation |
| 元件分類： | 通用總線功能 |
| 英文描述： | QUAD UART WITH RX/TX FIFO COUNTERS,128-BYTE FIFO |
| 中文描述： | 四路與異步接收/發(fā)送FIFO的計數器,128字節(jié)FIFO |
| 文件頁數： | 18/51頁 |
| 文件大?。?/td> | 476K |
| 代理商： | XR16C854 |
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XR16C854
18
Rev. 1.00P
C1
22pF
C2
33pF
X1
1.8432 MHz
X
X
Figure 8, Crystal oscillator connection
Hardware/Software and Timeout Interrupts
Three special interrupts have been added to monitor
the hardware and software flow control. The interrupts
are enabled by IER bits 5-7. Care must be taken when
handling these interrupts. Following a reset the trans-
mitter interrupt is enabled, the 854 will issue an
interrupt to indicate that transmit holding register is
empty. This interrupt must be serviced prior to con-
tinuing operations. The LSR register provides the
current singular highest priority interrupt only. It could
be noted that CTS and RTS interrupts have lowest
interrupt priority. A condition can exist where a higher
priority interrupt may mask the lower priority CTS/
RTS interrupt(s). Only after servicing the higher pend-
ing interrupt will the lower priority CTS/ RTS
interrupt(s) be reflected in the status register. Servic-
ing the interrupt without investigating further interrupt
conditions can result in data errors.
When two interrupt conditions have the same priority,
it is important to service these interrupts correctly.
Receive Data Ready and Receive Time Out have the
same interrupt priority (when enabled by IER bit-3).
The receiver issues an interrupt after the number of
characters have reached the programmed trigger
level. In this case the 854 FIFO may hold more
characters than the programmed trigger level. Follow-
ing the removal of a data byte, the user should recheck
LSR bit-0 for additional characters. A Receive Time
Out will not occur if the receive FIFO is empty. The
time out counter is reset at the center of each stop bit
received or each time the receive holding register
(RHR) is read. The actual time out value is T (
T
ime out
length in bits) = 4 X P (
P
rogrammed word length) + 12.
To convert the time out value to a character value, the
user has to consider the complete word length, includ-
ing data information length, start bit, parity bit, and the
size of stop bit, i.e., 1X, 1.5X, or 2X bit times.
Example -A: If the user programs a word length of 7,
with no parity and one stop bit, the time out will be:
T = 4 X 7( programmed word length) +12 = 40 bit times.
The character time will be equal to 40 / 9 = 4.4
characters, or as shown in the fully worked out ex-
ample: T = [(programmed word length = 7) + (stop bit
= 1) + (start bit = 1) = 9]. 40 (bit times divided by 9) =
4.4 characters.
Example -B: If the user programs the word length = 7,
with parity and one stop bit, the time out will be:
T = 4 X 7(programmed word length) + 12 = 40 bit times.
Character time = 40 / 10 [ (programmed word length
= 7) + (parity = 1) + (stop bit = 1) + (start bit = 1) = 4
characters.
In the 16 mode for 68/100 pin packages, the system/
board designer can optionally provide software con-
trolled three state interrupt operation. This is accom-
plished by INTSEL and MCR bit-3. When INTSEL
interface pin is left open or made a logic 0, MCR bit-
3 controls the three state interrupt outputs, INT A-D.
When INTSEL is a logic 1, MCR bit-3 has no effect on
the INT A-D outputs and the package operates with
interrupt outputs enabled continuously.
Programmable Baud Rate Generator
The 854 supports high speed modem technologies
that have increased input data rates by employing
data compression schemes. For example a 33.6Kbps
modem that employs data compression may require a
115.2Kbps input data rate. A 128.0Kbps ISDN modem
that supports data compression may need an input
data rate of 460.8Kbps. The 854 can support a stan-
dard data rate of 921.6Kbps.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| XR16C854CJ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| XR16C854CJ-0A-EVB | 功能描述:UART 接口集成電路 Supports C854 68 ld PLCC, ISA Interface RoHS:否 制造商:Texas Instruments 通道數量:2 數據速率:3 Mbps 電源電壓-最大:3.6 V 電源電壓-最小:2.7 V 電源電流:20 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:LQFP-48 封裝:Reel |
| XR16C854CJ-F | 功能描述:UART 接口集成電路 UART RoHS:否 制造商:Texas Instruments 通道數量:2 數據速率:3 Mbps 電源電壓-最大:3.6 V 電源電壓-最小:2.7 V 電源電流:20 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:LQFP-48 封裝:Reel |
| XR16C854CJTR-F | 制造商:Exar Corporation 功能描述:XR16C854CJTR-F |
| XR16C854CQ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
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