CS8900A-CQZ View Datasheet(PDF) - Cirrus Logic
Part Name
Description
Manufacturer
CS8900A-CQZ Datasheet PDF : 138 Pages
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CS8900A
Crystal LAN™ Ethernet Controller
Enter P acket Transm it Process
Exit: can't Issue com m and
Note: Issuing a com m and
at this point will cause
previous transmit frame
to be lost.
Is
TxCMD
Yes pending?
No
Host W rites Transm it Com m and
to the TxCMD Register
Ho st W rites Tran sm it Fram e
Length to the TxLength Register
Transmit Request
Host Reads the BusST
Register (Register 18)
Host Enters Interrupt Routine
Host Reads
IS Q
Rdy4
TxNOW
Yes
bit = 1?
No
Exit W AIT-for-interrupt
No R dy4T x Y es
bit = 1?
CS8900A Com mits
Buffer Space to
Transm it F ram e
Process other events
that caused interrupt
Host W rites
Transm it Frame
to CS8900A
CS8900A
Transm its Fram e
Exit Transmit Process
Figure 31. Transmit Operation in Interrupt Mode
5.6.9 Rdy4TxNOW vs. Rdy4Tx
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 pro-
cess or after the Transmit Request process to
signal the host that space has become avail-
able when interrupts are not being used (i.e.
the Rdy4TxiE bit (Register B, BufCFG, Bit 8) is
CIRRUS LOGIC PRODUCT DATASHEET
104
DS271F4
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