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参数资料
| 型号： | DS21FF44N |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Digital Transmission Controller |
| 英文描述： | DATACOM, FRAMER, PBGA300 |
| 封装： | 27 X 27 MM, BGA-300 |
| 文件页数： | 74/110页 |
| 文件大小： | 526K |
| 代理商： | DS21FF44N |
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DS21FT44/DS21FF44
66 of 110
NAME
FUNCTION
Receive HDLC FIFO Register (RHFR)
access to 64–byte HDLC FIFO in receive direction
Receive HDLC DS0 Control Register 1
(RDC1)
Receive HDLC DS0 Control Register 2
(RDC2)
controls the HDLC function when used on DS0 channels
Transmit HDLC Information Register
(THIR)
status information on transmit HDLC controller
Transmit HDLC FIFO Register (THFR)
access to 64–byte HDLC FIFO in transmit direction
Transmit HDLC DS0 Control Register 1
(TDC1)
Transmit HDLC DS0 Control Register 2
(TDC2)
controls the HDLC function when used on DS0 channels
19.2. HDLC STATUS REGISTERS
Three of the HDLC controller registers (HSR, RHIR, and THIR) provide status information. When a
particular event has occurred (or is occurring), the appropriate bit in one of these three registers will be
set to a one. Some of the bits in these three status registers are latched and some are real time bits that are
not latched. Section 19.4 contains register descriptions that list which bits are latched and which are not.
With the latched bits, when an event occurs and a bit is set to a one, it will remain set until the user reads
that bit. The bit will be cleared when it is read and it will not be set again until the event has occurred
again. The real time bits report the current instantaneous conditions that are occurring and the history of
these bits is not latched.
Like the other status registers in the framer, the user will always proceed a read of any of the three
registers with a write. The byte written to the register will inform the framer which of the latched bits the
user wishes to read and have cleared (the real time bits are not affected by writing to the status register).
The user will write a byte to one of these registers, with a one in the bit positions he or she wishes to read
and a zero in the bit positions he or she does not wish to obtain the latest information on. When a one is
written to a bit location, the read register will be updated with current value and it will be cleared. When
a zero is written to a bit position, the read register will not be updated and the previous value will be held.
A write to the status and information registers will be immediately followed by a read of the same
register. The read result should be logically AND’ed with the mask byte that was just written and this
value should be written back into the same register to insure that bit does indeed clear. This second write
step is necessary because the alarms and events in the status registers occur asynchronously in respect to
their access via the parallel port. This write–read–write (for polled driven access) or write–read (for
interrupt driven access) scheme allows an external microcontroller or microprocessor to individually poll
certain bits without disturbing the other bits in the register. This operation is key in controlling the
DS21Q44 with higher–order software languages.
相关PDF资料 |
PDF描述 |
|---|---|
| DS21FT40N | DATACOM, FRAMER, PBGA300 |
| DS21FT40 | DATACOM, FRAMER, PBGA300 |
| DS21FT42 | DATACOM, FRAMER, PBGA300 |
| DS21FT42N | DATACOM, FRAMER, PBGA300 |
| DS21FF42 | DATACOM, FRAMER, PBGA300 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS21FT40 | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Four x Three 12 Channel E1 Framer |
| DS21FT40N | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| DS21FT42 | 功能描述:网络控制器与处理器 IC 4x4 16/4x3 12 Chnl T1/T1 Framer RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| DS21FT42N | 功能描述:网络控制器与处理器 IC 4x4 16/4x3 12 Chnl T1/T1 Framer RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| DS21FT44 | 功能描述:网络控制器与处理器 IC RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
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