CS8900A
Crystal LAN™ ISA Ethernet Controller
Enter Packet Transmit Process
Is
TxCMD
pending?
Exit: can’t Issue command
Yes
Note: Issuing a command
at this point will cause
previous transmit frame
to be lost.
No
Host Writes Transmit Command
to the TxCMD Register
Host Writes Transmit Frame
Length to the TxLength Register
Transmit Request
Host Reads the BusST
Register (Register 18)
Rdy4
No
Polling Loop
TxNOW
bit = 1?
Yes
CS8900A Commits
Buffer Space to
Transmit Frame
Host Writes
Transmit Frame
to CS8900A
CS8900A
Transmits Frame
Exit Transmit Process
Figure 30. Transmit Operation in Polling Mode
mode). If the transmit length is erroneous, the
command is discarded and the TxBidErr, bit 7,
in BusST register is set.
3) The host reads the BusST register. This read is
performed in memory mode by reading Regis-
ter 18, at memory base + 0138h. In I/O mode,
the host must first set the PacketPage Pointer at
CIRRUS LOGIC PRODUCT DATA SHEET
102
DS271PP3
CIRRUS [ CIRRUS LOGIC ]
