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參數(shù)資料
| 型號： | DS3134 |
| 廠商： | DALLAS SEMICONDUCTOR |
| 元件分類： | Digital Transmission Controller |
| 英文描述： | DATACOM, FRAMER, PBGA256 |
| 封裝： | 27 X 27 MM, PLASTIC, BGA-256 |
| 文件頁數(shù)： | 24/203頁 |
| 文件大?。?/td> | 777K |
| 代理商： | DS3134 |
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DS3134
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When the DMA begins burst writing data into the FIFO, it will try to completely fill the FIFO with HDLC
packet data even if it that means writing multiple packets. Once the FIFO detects that the DMA has filled
it to beyond the Low Water Mark (or an EOF is reached), the FIFO will begin transferring 32-bit dwords
to the HDLC Engine.
One of the unique attributes of the DS3134 is the structure of the DMA. The DMA has been optimized to
maintain maximum flexibility yet reduce the number of bus cycles required to transfer packet data. The
DMA uses a flexible scatter/gather technique, which allows that packet data to be place anywhere within
the 32-bit address space. The user has the option on the receive side of two different buffer sizes which
are called “l(fā)arge” and “small” but that can be set to any size up to 8191 bytes. The user has the option to
store the incoming data either, only in the large buffers, only in the small buffers, or fill a small buffer
first and then fill large buffers as needed. The varying buffer storage options allow the user to make the
best use of the available memory and to be able to balance the tradeoff between latency and bus
utilization.
The DMA uses a set of descriptors to know where to store the incoming HDLC packet data and where to
obtain HDLC packet data that is ready to be transmitted. The descriptors are fixed size messages that are
handed back and forth from the DMA to the Host. Since this descriptor transfer utilizes bus cycles, the
DMA has been structured to minimize the number of transfers required. For example on the receive side,
the DMA obtains descriptors from the Host to know where in the 32-bit address space to place the
incoming packet data. These descriptors are known as Free Queue Descriptors. When the DMA reads
these descriptors off of the PCI Bus, they contain all the information that the DMA needs to know where
to store the incoming data. Unlike other existing scatter/gather DMA architectures, the DS3134 DMA
does not need to use any more bus cycles to determine where to place the data. Other DMA architectures
tend to use pointers, which require them to go back onto the bus to obtain more information and hence
use more bus cycles.
Another technique that the DMA uses to maximize bus utilization is the ability to burst read and writes
the descriptors. The device can be enabled to read and write the descriptors in bursts of 8 or 16 instead of
one at a time. Since there is fixed overhead associated with each bus transaction, the ability to burst read
and write descriptors allows the device to share the bus overhead among 8 or 16 descriptor transactions
which reduces the total number of bus cycles needed.
The DMA can also burst up to 256 dwords (1024 bytes) onto the PCI Bus. This helps to minimize bus
cycles by allowing the device to burst large amounts of data in a smaller number of bus transactions
which reduces bus cycles by reducing the amount of fixed overhead that is placed on the bus.
The Local Bus Block has two modes of operation. It can be used as either a Bridge from the PCI Bus in
which case it is a bus master or it can be used as a Configuration Bus in which case it is a bus slave. The
Bridge Mode allows the Host on the PCI Bus to access the local bus. The DS3134 will map data from the
PCI Bus to the local bus. In the Configuration Mode, the local bus is used only to control and monitor the
DS3134 while the HDLC packet data will still be transferred to the Host via the PCI Bus.
Restrictions
In creating the overall system architecture, the user must balance the port, throughput, and HDLC channel
restrictions of the DS3134. Table 1D lists all of the upper bound maximum restrictions on the DS3134.
相關(guān)PDF資料 |
PDF描述 |
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| DS3150QN | DATACOM, PCM TRANSCEIVER, PQCC28 |
| DS3150Q | DATACOM, PCM TRANSCEIVER, PQCC28 |
| DS3150TN | DATACOM, PCM TRANSCEIVER, PDIP48 |
| DS3150T | DATACOM, PCM TRANSCEIVER, PQFP48 |
| DS5000FP-12 | 8-BIT, 12 MHz, MICROCONTROLLER, PQFP80 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS-313PIN | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog Miscellaneous |
| DS-313-PIN | 功能描述:信號調(diào)節(jié) RoHS:否 制造商:EPCOS 產(chǎn)品:Duplexers 頻率:782 MHz, 751 MHz 頻率范圍: 電壓額定值: 帶寬: 阻抗:50 Ohms 端接類型:SMD/SMT 封裝 / 箱體:2.5 mm x 2 mm 工作溫度范圍:- 30 C to + 85 C 封裝:Reel |
| DS31400 | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:8-Input, 14-Output, Dual DPLL Timing IC with Sub-ps Output Jitter |
| DS31400DK | 功能描述:時(shí)鐘和定時(shí)器開發(fā)工具 DS31400 Dev Kit RoHS:否 制造商:Texas Instruments 產(chǎn)品:Evaluation Modules 類型:Clock Conditioners 工具用于評估:LMK04100B 頻率:122.8 MHz 工作電源電壓:3.3 V |
| DS31400GN | 功能描述:計(jì)時(shí)器和支持產(chǎn)品 Not Available From Mouser RoHS:否 制造商:Micrel 類型:Standard 封裝 / 箱體:SOT-23 內(nèi)部定時(shí)器數(shù)量:1 電源電壓-最大:18 V 電源電壓-最小:2.7 V 最大功率耗散: 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝:Reel |
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