CRD8900A-1 Cirrus Logic Inc, CRD8900A-1 Datasheet - Page 104

• Manufacturer Part Number: CRD8900A-1
• Description: KIT EVAL FOR CS8900A
• Manufacturer: Cirrus Logic Inc
• Series: CrystalLAN™r

Specifications of CRD8900A-1

• Main Purpose: Interface, Ethernet
• Utilized Ic / Part: CS8900A
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Secondary Attributes: -
• Embedded: -
• Primary Attributes: -
• Other names: 598-1163

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-
104
Process other events
that caused interrupt
Host Enters Interrupt Routine
No
Host Reads
Exit: can't Issue command
Note: Issuing a command
at this point will cause
previous transmit frame
to be lost.
Rdy4Tx
bit = 1?
ISQ
Figure 31. Transmit Operation in Interrupt Mode
CIRRUS LOGIC PRODUCT DATASHEET
Yes
Host Writes Transmit Command
Enter Packet Transmit Process
Length to the TxLength Register
Yes
Host Writes Transmit Frame
Exit Transmit Process
to the TxCMD Register
CS8900A Commits
Exit WAIT-for-interrupt
Host Reads the BusST
Register (Register 18)
Transmits Frame
Transmit Frame
Buffer Space to
Transmit Frame
to CS8900A
Host Writes
CS8900A
pending?
No
TxCMD
TxNOW
No
bit = 1?
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
Rdy4
Is
Yes
Crystal LAN™ Ethernet Controller
Transmit Request
CS8900A
DS271F5