CS8900-CQ3 Cirrus Logic, CS8900-CQ3 Datasheet - Page 102

• Manufacturer Part Number: CS8900-CQ3
• Description: Crystal LAN ISA Ethernet Controller
• Manufacturer: Cirrus Logic

102
mode). If the transmit length is erroneous, the
command is discarded and the TxBidErr, bit 7,
in BusST register is set.
Exit: can’t Issue command
Note: Issuing a command
at this point will cause
previous transmit frame
to be lost.
Figure 30. Transmit Operation in Polling Mode
CIRRUS LOGIC PRODUCT DATA SHEET
Host Writes Transmit Command
Length to the TxLength Register
Enter Packet Transmit Process
Host Writes Transmit Frame
Yes
to the TxCMD Register
Host Reads the BusST
Exit Transmit Process
Register (Register 18)
CS8900A Commits
Transmits Frame
Transmit Frame
Transmit Frame
Buffer Space to
to CS8900A
Host Writes
Yes
CS8900A
pending?
No
TxNOW
TxCMD
bit = 1?
Rdy4
Is
No
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
Crystal LAN™ ISA Ethernet Controller
Polling Loop
Transmit Request
CS8900A
DS271PP3