欢迎访问ic37.com |
会员登录 免费注册
发布采购

CS8900A-IQ3 参数 Datasheet PDF下载

CS8900A-IQ3图片预览
型号: CS8900A-IQ3
PDF下载: 下载PDF文件 查看货源
内容描述: 水晶局域网? ISA以太网控制器 [Crystal LAN ⑩ ISA Ethernet Controller]
分类和应用: 控制器局域网以太网
文件页数/大小: 128 页 / 1360 K
品牌: CIRRUS [ CIRRUS LOGIC ]
 浏览型号CS8900A-IQ3的Datasheet PDF文件第99页浏览型号CS8900A-IQ3的Datasheet PDF文件第100页浏览型号CS8900A-IQ3的Datasheet PDF文件第101页浏览型号CS8900A-IQ3的Datasheet PDF文件第102页浏览型号CS8900A-IQ3的Datasheet PDF文件第104页浏览型号CS8900A-IQ3的Datasheet PDF文件第105页浏览型号CS8900A-IQ3的Datasheet PDF文件第106页浏览型号CS8900A-IQ3的Datasheet PDF文件第107页  
CS8900A  
Crystal LAN™ ISA Ethernet Controller  
the correct location by writing 0138h to the  
PacketPage Pointer Port (I/O base + 000Ah), it  
than can read the BusST register from the Pack-  
etPage Data Port (I/O base + 000Ch).After  
reading the register, the Rdy4TxNOW bit is  
checked. If the bit is set, the frame can be writ-  
ten to CS8900A memory. If Rdy4TxNOW is  
clear, the host will have to wait for the  
CS8900A buffer memory to become available  
at which time the host will be interrupted. On  
interrupt, the host enters the interrupt service  
routine and reads ISQ register (Memory base +  
0120h in memory mode and I/O base + 0008h  
in I/O) and checks the Rdy4Tx bit (bit 8). If  
Rdy4Tx is clear then the CS8900A waits for the  
next interrupt. If Rdy4Tx is set, then the  
CS8900A is ready to accept the frame.  
Figure 30 provides a diagram of error free trans-  
mission without collision.  
5.7.10 Committing Buffer Space to a Transmit  
Frame  
When the host issues a transmit request, the  
CS8900A checks the length of the transmit frame  
to see if there is sufficient on-chip buffer space. If  
there is, the CS8900A sets the Rdy4TxNOW bit. If  
not, and the Rdy4TxiE bit is set, the CS8900A  
waits for buffer space to free up and then sets the  
Rdy4Tx bit. If Rdy4TxiE is not set, the CS8900A  
sets the Rdy4TxNOW bit when space becomes  
available.  
Even though transmit buffer space may be avail-  
able, the CS8900A does not commit buffer space to  
a transmit frame until all of the following are true:  
1) The host must issues a Transmit Request;  
4) When the CS8900A is ready to accept the  
frame, the host transfers the entire frame from  
host memory to CS8900A memory using REP  
instruction (REP MOVS to memory base +  
0A00h in memory mode, and REP OUT to Re-  
ceive/Transmit Data Port (I/O base + 0000h) in  
I/O mode).  
2) The Transmit Request must be successful; and,  
3) Either the host reads that the Rdy4TxNOW bit  
(Register 18, BusST, Bit 8) is set, or the host  
reads that the Rdy4Tx bit (Register C, BufE-  
vent, bit 8) is set.  
If the CS8900A commits buffer space to a particu-  
lar transmit frame, it will not allow subsequent  
frames to be written to that buffer space as long as  
the transmit frame is committed.  
5.7.8 Completing Transmission  
When the CS8900A successfully completes trans-  
mitting a frame, it sets the TxOK bit (Register 8,  
TxEvent, Bit 8). If the TxOKiE bit (Register 7, Tx-  
CFG, bit 8) is set, the CS8900A generates a corre-  
sponding interrupt.  
After buffer space is committed, the frame is sub-  
sequently transmitted unless any of the following  
occur:  
5.7.9 Rdy4TxNOW vs. Rdy4Tx  
1) The host completely writes the frame data, but  
transmission failed on the Ethernet line. There  
are three such failures, and these are indicated  
by three transmit error bits in the TxEvent reg-  
ister (Register 8): 16coll, Jabber, or Out-of-  
Window.  
The Rdy4TxNOW bit (Register 18, BusST, bit 8) is  
used to tell the host that the CS8900A is ready to  
accept a frame for transmission. This bit is used  
during the Transmit Request process or after the  
Transmit Request process to signal the host that  
space has become available when interrupts are not  
being used (i.e. the Rdy4TxiE bit (Register B,  
BufCFG, Bit 8) is not set). Also, the Rdy4Tx bit is  
used with interrupts and requires the Rdy4TxiE bit  
be set.  
Or:  
2) The host aborts the transmission by setting the  
Force (Register 9, TxCMD, bit 8) bit. In this  
case, the committed transmit frame, as well as  
CIRRUS LOGIC PRODUCT DATA SHEET  
DS271PP3  
103  
 复制成功!