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| 型号： | DS3131 |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | Telecom IC:Other |
| 英文描述： | SPECIALTY TELECOM CIRCUIT, PBGA256 |
| 封装： | 27 X 27 MM, PLASTIC, BGA-256 |
| 文件页数： | 165/174页 |
| 文件大小： | 1261K |
| 代理商： | DS3131 |
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DS3131
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Buffer Write Threshold Setting
In the DMA configuration RAM (Section 9.2.5), there is a host-controlled field called “threshold” (bits
RDT0 to RDT2) that informs the DMA when it should write to the done queue. The host has the option
to have the DMA place information in the done queue after a programmable number (from 1 to 7) data
buffers have been filled or wait until the completed packet data has been written. The DMA always
writes to the done queue when it has finished receiving a packet, even if the threshold has not been met.
Done-Queue Burst Writing
The DMA has the ability to write to the done queue in bursts, which allows for a more efficient use of
the PCI bus. The DMA can hand off descriptors to the done queue in groups rather than one at a time,
freeing up the PCI bus for more time-critical functions.
An internal FIFO stores up to eight done-queue descriptors (8 dwords as each descriptor occupies one
dword). The host must configure the FIFO for proper operation through the receive DMA queues-control
(RDMAQ) register (see the following).
When enabled through the receive done-queue FIFO-enable (RDQFE) bit, the done-queue FIFO does not
write to the done queue until it reaches the high watermark. When the done-queue FIFO reaches the high
watermark (which is six descriptors), it attempts to empty the done-queue FIFO by burst writing to the
done queue. Before it writes to the done queue, it checks (by examining the receive done-queue host read
pointer) to ensure the done queue has enough room to empty the done-queue FIFO. If the done queue
does not have enough room, then it only burst writes enough descriptors to keep from overflowing the
done queue. If the FIFO detects that there is no room for any descriptors to be written, it sets the status
bit for the receive DMA done-queue write error (RDQWE) in the status register for DMA (SDMA). It
does not write to the done queue nor does it increment the write pointer. In such a scenario, packets can
be lost and unrecoverable. If the done-queue FIFO can write descriptors to the done queue, it burst writes
them, increments the write pointer, and sets the status bit for the receive DMA done-queue write
(RDQW) in the status register for DMA (SDMA). See Section 5 for more details on status bits.
Done-Queue FIFO Flush Timer
To ensure the done-queue FIFO gets flushed to the done queue on a regular basis, the DMA uses the
receive done-queue FIFO flush timer (RDQFFT) to determine the maximum wait time between writes.
The RDQFFT is a 16-bit programmable counter that is decremented every PCLK divided by 256. It is
only monitored by the DMA when the receive done-queue FIFO is enabled (RDQFE = 1). For a 33MHz
PCLK, the timer is decremented every 7.76
s. Each time the DMA writes to the done queue it resets the
timer to the count placed into it by the host. On initialization, the host sets a value into the RDQFFT that
indicates the maximum time the DMA should wait in between writes to the done queue. For example,
with a PCLK of 33MHz, the range of wait times is from 7.8
s (RDQFFT = 0001h) to 508ms
(RDQFFT = FFFFh).
相关PDF资料 |
PDF描述 |
|---|---|
| DS3134 | DATACOM, FRAMER, PBGA256 |
| DS3150QN | DATACOM, PCM TRANSCEIVER, PQCC28 |
| DS3150Q | DATACOM, PCM TRANSCEIVER, PQCC28 |
| DS3150TN | DATACOM, PCM TRANSCEIVER, PDIP48 |
| DS3150T | DATACOM, PCM TRANSCEIVER, PQFP48 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS3131DK | 功能描述:通信集成电路 - 若干 RoHS:否 制造商:Maxim Integrated 类型:Transport Devices 封装 / 箱体:TECSBGA-256 数据速率:100 Mbps 电源电压-最大:1.89 V, 3.465 V 电源电压-最小:1.71 V, 3.135 V 电源电流:50 mA, 225 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装:Tube |
| DS3134 | 功能描述:IC CTRLR HDLC CHATEAU 256-BGA RoHS:否 类别:集成电路 (IC) >> 接口 - 控制器 系列:- 标准包装:4,900 系列:- 控制器类型:USB 2.0 控制器 接口:串行 电源电压:3 V ~ 3.6 V 电流 - 电源:135mA 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:36-VFQFN 裸露焊盘 供应商设备封装:36-QFN（6x6） 包装:* 其它名称:Q6396337A |
| DS-313PIN | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Analog Miscellaneous |
| DS-313-PIN | 功能描述:信号调节 RoHS:否 制造商:EPCOS 产品:Duplexers 频率:782 MHz, 751 MHz 频率范围: 电压额定值: 带宽: 阻抗:50 Ohms 端接类型:SMD/SMT 封装 / 箱体:2.5 mm x 2 mm 工作温度范围:- 30 C to + 85 C 封装:Reel |
| DS31400 | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:8-Input, 14-Output, Dual DPLL Timing IC with Sub-ps Output Jitter |
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