參數(shù)資料
型號： XR16C864
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 and 128-byte FIFO(四通用異步接收器/發(fā)送器（帶RX/TX 先進先出計數(shù)器和128字節(jié)先進先出）)
中文描述： 四路與異步接收/發(fā)送FIFO的計數(shù)器和128字節(jié)的FIFO（四通用異步接收器/發(fā)送器（帶了Rx / Tx先進先出計數(shù)器和128字節(jié)先進先出））
文件頁數(shù)： 15/46頁
文件大?。?/td> 381K
代理商： XR16C864
XR16C864
15
Rev. 1.10
Software Flow Control
When software flow control is enabled, the 864 com-
pares one or two sequential receive data characters with
the programmed Xon or Xoff-1,2 character value(s). If
receive character(s) match the programmed values, the
864 will halt transmission as soon as the current
character has completed transmission. When a match
occurs, the receive ready (if enabled via Xoff IER bit-5)
flags will be set and the interrupt output pin (if receive
interrupt is enabled) will be activated. Following a
suspension due to a match of the Xoff characters values,
the 864 will monitor the receive data stream for a match
to the Xon-1,2 character value(s). If a match is found, the
864 will resume operation and clear the flags (ISR bit-4).
The 864 offers a special Xon-Any mode via MCR bit-5.
The initialized default setting of MCR bit-5 is a logic 0.
In this state Xoff and Xon will operate as defined above.
Setting MCR bit-5 to a logic 1 sets a special operational
mode for the Xon function. In this case Xoff operates
normally however, transmission (Xon) will resume with
the next character received, i.e., a match is declared
simply by the receipt of an incoming (RX) character.
Reset initially sets the contents of the Xon/Xoff 8-bit
flow control registers to a logic 0. Following reset the
user can write any Xon/Xoff value desired for software
flow control. Different conditions can be set to detect
Xon/Xoff characters and suspend/resume transmis-
sions. When double 8-bit Xon/Xoff characters are se-
lected, the 864 compares two consecutive receive
characters with two software flow control 8-bit values
(Xon1, Xon2, Xoff1, Xoff2) and controls TX transmis-
sions accordingly. Under the above described flow
control mechanisms, flow control characters are not
placed (stacked) in the user accessible RX data buffer
or FIFO.
In the event that the receive buffer is overfilling and
flow control needs to be executed, the 864 automati-
cally sends an Xoff message (when enabled) via the
serial TX output to the remote modem. The 864 sends
the Xoff-1,2 characters as soon as received data
passes the programmed trigger level. To clear this
condition, the 864 will transmit the programmed Xon-
1,2 characters as soon as receive data drops below
the next lower programmed trigger level (see previous
table).
Special Feature Software Flow Control
A special feature is provided to detect an 8-bit character
when bit-5 is set in the Enhanced Feature Register
(EFR). When 8 bit character is detected, it will be
placed on the user accessible data stack along with
normal incoming RX data. This condition is selected in
conjunction with EFR bits 0-3. Note that software flow
control should be turned off when using this special
mode by setting EFR bit 0-3 to a logic 0.
The 864 compares each incoming receive character
with Xoff-2 data. If a match exists, the received data
will be transferred to FIFO and ISR bit-4 will be set to
indicate detection of special character. Although the
Internal Register Table shows each X-Register with
eight bits of character information, the actual number of
bits is dependent on the programmed word length. Line
Control Register (LCR) bits 0-1 defines the number of
character bits, i.e., either 5 bits, 6 bits, 7 bits, or 8 bits.
The word length selected by LCR bits 0-1 also deter-
mines the number of bits that will be used for the special
character comparison. Bit-0 in the X-registers corre-
sponds with the LSB bit for the receive character.
Xon Any Feature
A special feature is provided to return the Xoff flow
control to the inactive state following its activation. In
this mode any RX character received will return the Xoff
flow control to the inactive state so that transmissions
may be resumed with a remote buffer. This feature is
more fully defined in the Software Flow Control section.
Device Identification
The XR16C864 provides Device identification and
Device Revision code to distinguish the part from
others.
To read the identification number from the part, its is
required to set the baud rate generator divisor latch (LCR
register bit-7) to “1” and then set the content of the baud
rate generator DLL and DLM registers to “0”. Reading
the content of the DLM will provide “14” hex for
XR16C864 part and reading the content of the DLL will
provide the revision of the part.
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XR16C864CQ-0A-EVB 功能描述:UART 接口集成電路 Supports C864 100 ld QFP, ISA Interface RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 數(shù)據(jù)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
XR16C864CQ-0B-EB 功能描述:界面開發(fā)工具 Eval Board for XR16C864CQ Series RoHS:否 制造商:Bourns 產(chǎn)品:Evaluation Boards 類型:RS-485 工具用于評估:ADM3485E 接口類型:RS-485 工作電源電壓:3.3 V
XR16C864CQ-F 功能描述:UART 接口集成電路 UART RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 數(shù)據(jù)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
XR16C864CQTR-F 功能描述:UART 接口集成電路 UART RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 數(shù)據(jù)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
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