参数资料
| 型号： | XR16M2751IM48-F |
| 厂商： | Exar Corporation |
| 文件页数： | 10/53页 |
| 文件大小： | 0K |
| 描述： | IC UART FIFO 64B DUAL 48TQFP |
| 标准包装： | 250 |
| 特点： | * |
| 通道数： | 2，DUART |
| FIFO's： | 64 字节 |
| 规程： | RS232，RS485 |
| 电源电压： | 1.62 V ~ 3.63 V |
| 带自动流量控制功能： | 是 |
| 带IrDA 编码器/解码器： | 是 |
| 带故障启动位检测功能： | 是 |
| 带调制解调器控制功能： | 是 |
| 带CMOS： | 是 |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 48-TQFP |
| 供应商设备封装： | 48-TQFP（7x7） |
| 包装： | 托盘 |
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XR16M2751
18
1.62V TO 3.63V HIGH PERFORMANCE DUART WITH 64-BYTE FIFO
REV. 1.0.0
2.15
Auto Xon/Xoff (Software) Flow Control
When software flow control is enabled (See Table 16), the M2751 compares one or two sequential receive
data characters with the programmed Xon or Xoff-1,2 character value(s). If receive character(s) (RX) match the
programmed values, the M2751 will halt transmission (TX) as soon as the current character has completed
transmission. When a match occurs, the Xoff (if enabled via IER bit-5) flag will be set and the interrupt output
pin will be activated. Following a suspension due to a match of the Xoff character, the M2751 will monitor the
receive data stream for a match to the Xon-1,2 character. If a match is found, the M2751 will resume operation
and clear the flags (ISR bit-4).
Reset initially sets the contents of the Xon/Xoff 8-bit flow control registers to 0x00. 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 (See Table 16) and suspend/resume transmissions. When double 8-bit Xon/Xoff characters are
selected, the M2751 compares two consecutive receive characters with two software flow control 8-bit values
(Xon1, Xon2, Xoff1, Xoff2) and controls TX transmissions 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 M2751
automatically sends an Xoff message via the serial TX output to the remote modem. The M2751 sends the
Xoff-1,2 characters two-character times (= time taken to send two characters at the programmed baud rate)
after the receive FIFO crosses the programmed trigger level (for all trigger tables). To clear this condition, the
M2751 will transmit the programmed Xon-1,2 characters as soon as receive FIFO is less than one trigger level
below the programmed trigger level (for Trigger Tables A, B, and C) or when receive FIFO is less than the
trigger level minus the hysteresis value (for Trigger Table D). This hysteresis value is the same as the Auto
RTS Hysteresis value in Table 15. Table 7 below explains this when Trigger Table-B (See Table 11) is
selected.
* After the trigger level is reached, an xoff character is sent after a short span of time (= time required to send 2
characters); for example, after 2.083ms has elapsed for 9600 baud and 10-bit word length setting.
2.16
Special Character Detect
A special character detect feature is provided to detect an 8-bit character when bit-5 is set in the Enhanced
Feature Register (EFR). When this character (Xoff2) is detected, it will be placed in the FIFO along with normal
incoming RX data.
The M2751 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 Xon, Xoff Registers 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
determines the number of bits that will be used for the special character comparison. Bit-0 in the Xon, Xoff
Registers corresponds with the LSB bit for the receive character.
2.17
Auto RS485 Half-duplex Control
The auto RS485 half-duplex direction control changes the behavior of the transmitter when enabled by FCTR
bit-3. By default, it de-asserts RTS# (HIGH) output following the last stop bit of the last character that has been
transmitted. This helps in turning around the transceiver to receive the remote station’s response. When the
host is ready to transmit next polling data packet again, it only has to load data bytes to the transmit FIFO. The
TABLE 7: AUTO XON/XOFF (SOFTWARE) FLOW CONTROL
RX TRIGGER LEVEL
INT PIN ACTIVATION
XOFF CHARACTER(S) SENT
(CHARACTERS IN RX FIFO)
XON CHARACTER(S) SENT
(CHARACTERS IN RX FIFO)
8
8*
0
16
16*
8
24
24*
16
28
28*
24
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相关代理商/技术参数 |
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| XR16M2752 | 制造商:EXAR 制造商全称:EXAR 功能描述:1.62V TO 3.63V HIGH PERFORMANCE DUART WITH 64-BYTE FIFO |
| XR16M2752_07 | 制造商:EXAR 制造商全称:EXAR 功能描述:1.62V TO 3.63V HIGH PERFORMANCE DUART WITH 64-BYTE FIFO |
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| XR16M2752IJ-0B-EB | 功能描述:界面开发工具 Eval Board for XR16M2752IJ Series RoHS:否 制造商:Bourns 产品:Evaluation Boards 类型:RS-485 工具用于评估:ADM3485E 接口类型:RS-485 工作电源电压:3.3 V |
| XR16M2752IJ44 | 制造商:EXAR 制造商全称:EXAR 功能描述:1.62V TO 3.63V HIGH PERFORMANCE DUART WITH 64-BYTE FIFO |
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