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参数资料
| 型号： | DS3112 |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Digital Transmission Controller |
| 英文描述： | DATACOM, FRAMER, PBGA256 |
| 封装： | 27 X 27 MM, PLASTIC, BGA-256 |
| 文件页数： | 33/134页 |
| 文件大小： | 900K |
| 代理商： | DS3112 |
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DS3112
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T3 Framing Structure
As with M12, to understand the M23 function requires an understanding of T3 framing. The T3 frame
structure is very similar to the T2 frame structure however it is made up of seven M subframes. See
Figure 14.2C.
The seven M subframes are transmitted one after another (...M1/M2/M3/.../
M6/M7M1/M2...) to make up the complete T3 M frame structure. Each M subframe is made up of eight
blocks and each block is made up of 85 bits. The first bit of each block is dedicated to overhead and the
next 84 bits are the information bits where the T2 data will be placed for transport. The definition of the
overhead bits is shown in Table 14.2C and the placement of the overhead bits is shown in Figure 14.2C.
T3 Overhead Bit Assignments Table 14.2C
Overhead Bit
Description
M Bits
(M1/M2/M3)
The M bits provide the frame alignment pattern for the seven M subframes. Like all
framing patterns, the M bits are fixed to a certain state (M1 = 0 / M2 = 1 / M3 = 0).
F Bits
(F1/F2/F3/F4)
The F bits provide the frame alignment pattern for the M frame. Like all framing
patterns, the F bits are fixed to a certain state (F1 = 1 / F2 = 0 / F3 = 0 / F4 = 1).
C Bits
(C1/C2/C3)
In the M23 application, the C bits are used to indicate when stuffing occurs. If all
three C Bits within a subframe are set to 1, then stuffing has occurred in the stuff
block of that subframe. If all three C Bits are set to zero, then no stuffing has
occurred. When the three C bits are not equal, a majority vote is used to determine
the true state.
In the C-Bit Parity application, the C bits are defined as shown in Table 14.2D.
P Bits
(P1/P2)
The P bits provide parity information for the preceding M frame (not including the
M, F, X, and C overhead bits). P1 and P2 are always the same value (if they are not
the same value, this implies a parity error).
X Bits
(X1/X2)
The X bit is used as a Remote Alarm Indication (RAI). It will be set to a zero (X1 =
X2 = 0) when the T3 framer cannot synchronize or detects AIS. It will be set to a
one (X1 = X2 = 1) otherwise. The value of the X bits should not change more than
once per second. X1 and X2 are always the same value.
M23 Multiplexing
The M23 function multiplexes seven T2 data streams into a single T3 data stream. The seven T2 data
streams are bit interleaved into the T3 framing structure. A bit from T2 line #1 is placed immediately
after the overhead bit in the information bit field, followed by a bit from T2 line #2, and so on. Since
there are 84 information bits in each block, there are 12 bits from each T2 line in a block.
The seven T2 lines are mapped asynchronously into the T3 data stream. This implies that there is no T2
framing information passed to the T3 level. The seven T2 lines can have independent timing sources and
they do not need to be timing locked to the T3 clock. To account for differences in timing, bit stuffing is
used. The last block of each M subframe is the stuff block. See Figure 14.2C. In each stuff block there
is an associated stuff bit (see Figure 14.2D) that will be either an information bit (if the three C bits are
decoded to be zero) or a stuff bit (if the three C bits are decoded to be a one). As shown in Figure 14.2D,
the position of the stuff bit varies depending on the M subframe. This is done to allow a stuffing
opportunity to occur on each T2 line in every T3 frame. For example, if the C Bits in M Subframe 5 were
all set to one, then the fifth bit after the F4 overhead bit in the last block would be a stuff bit instead of an
information bit.
相关PDF资料 |
PDF描述 |
|---|---|
| DS3131 | SPECIALTY TELECOM CIRCUIT, PBGA256 |
| DS3134 | DATACOM, FRAMER, PBGA256 |
| DS3150QN | DATACOM, PCM TRANSCEIVER, PQCC28 |
| DS3150Q | DATACOM, PCM TRANSCEIVER, PQCC28 |
| DS3150TN | DATACOM, PCM TRANSCEIVER, PDIP48 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS3112+ | 功能描述:网络控制器与处理器 IC TEMPE T3/E3 MUX FRMR & M13/E13/G.747 MUX 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 |
| DS3112+W | 功能描述:网络控制器与处理器 IC TEMPE T3/E3 MUX FRMR & M13/E13/G.747 MUX 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 |
| DS3112D1 | 功能描述:网络控制器与处理器 IC TEMPE T3/E3 MUX FRMR & M13/E13/G.747 MUX 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 |
| DS3112D1+ | 功能描述:网络控制器与处理器 IC TEMPE T3/E3 MUX FRMR & M13/E13/G.747 MUX 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 |
| DS3112DK | 功能描述:网络开发工具 DS3112 Dev Kit RoHS:否 制造商:Rabbit Semiconductor 产品:Development Kits 类型:Ethernet to Wi-Fi Bridges 工具用于评估:RCM6600W 数据速率:20 Mbps, 40 Mbps 接口类型:802.11 b/g, Ethernet 工作电源电压:3.3 V |
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