欢迎访问ic37.com |
会员登录 免费注册
发布采购

PM7380-PI 参数 Datasheet PDF下载

PM7380-PI图片预览
型号: PM7380-PI
PDF下载: 下载PDF文件 查看货源
内容描述: 帧引擎和数据链路管理32P672 [FRAME ENGINE AND DATA LINK MANAGER 32P672]
分类和应用:
文件页数/大小: 332 页 / 2479 K
品牌: PMC [ PMC-SIERRA, INC ]
 浏览型号PM7380-PI的Datasheet PDF文件第74页浏览型号PM7380-PI的Datasheet PDF文件第75页浏览型号PM7380-PI的Datasheet PDF文件第76页浏览型号PM7380-PI的Datasheet PDF文件第77页浏览型号PM7380-PI的Datasheet PDF文件第79页浏览型号PM7380-PI的Datasheet PDF文件第80页浏览型号PM7380-PI的Datasheet PDF文件第81页浏览型号PM7380-PI的Datasheet PDF文件第82页  
RELEASED  
PM7380 FREEDM-32P672  
DATA SHEET  
PMC-1990262  
ISSUE 5  
FRAME ENGINE AND DATA LINK MANAGER 32P672  
Field  
Description  
TMAC Next TD Pointer The TMAC Next TD Pointer[14:0] bits are used to  
[14:0]  
store TDRs which permits the TMAC672 to create  
linked lists of TDs passed to it via the TDRR queue.  
The TDs are linked with other TDs belonging to the  
same channel and same priority level. In the case  
that data presented to the TMAC672 is returned to  
the host due to a channel becoming unprovisioned, a  
TDR pointing to the start of the per-channel linked list  
of TDs is placed on the TDRF queue. It is the  
responsibility of the host to follow the TMAC672 and  
host links in order to recover all the buffers.  
M
The More (M) bit is used by the host to support  
packets that require multiple TDs. If M is set to  
logic 1, the current TD is just one of several TDs for  
the current packet. If M is set to logic 0, this TD  
either describes the entire packet (in the single TD  
packet case) or describes the end of a packet (in the  
multiple TD packet case).  
Note: When M is set to logic 1, the only valid value  
for CE is logic 0.  
Host Next TD Pointer  
[14:0]  
The Host Next TD Pointer[14:0] bits are used to store  
TDRs which permits the host to support linked lists of  
TDs. As described above, linked lists of TDs are  
terminated by setting the CE bit to logic 1. Linked  
lists of TDs are used by the host to pass multiple TD  
packets or multiple packets associated with the same  
channel and priority level to the TMAC672.  
Transmit Buffer Size  
[15:0]  
The Transmit Buffer Size[15:0] field is used to  
indicate the size in bytes of the current TD's data  
buffer. (N.B. The TMAC672 does not make use of  
this field.)  
Transmit Descriptor Table  
The Transmit Descriptor Table, which resides in host memory, contains all of the  
Transmit Descriptors referenced by the TMAC672. To access a TD, the  
TMAC672 takes a TDR from a TDRR queue or from the TCDR table and adds  
16 times its value (because each TD is 16 bytes in size) to the Transmit  
Descriptor Table Base (TDTB) pointer to form the actual address of the TD in  
host memory. Each TD must reside in the Transmit Descriptor Table. The  
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA,INC., AND FOR ITS CUSTOMERS’ INTERNAL USE  
67  
 复制成功!