CS8900A
Crystal LAN™ Ethernet Controller
001000
These bits provide an internal address used by the CS8900A to identify this as the Transmitter
Event Register.
Loss-of-CRS
If the CS8900A is transmitting on the AUI and doesn't see Carrier Sense (CRS) at the end of
the preamble, there is a Loss-of-Carrier error and this bit is set. If Loss-of-CRSiE (Register 7,
TxCFG, Bit 6) is set, there is an interrupt.
SQEerror
TxOK
At the end of a transmission on the AUI, the CS8900A expects to see a collision within 64 bit
times. If this does not happen, there is an SQE error and this bit is set. If SQEerroriE (Register
7, TxCFG, Bit 7) is set, there is an interrupt.
This bit is set if the last packet was completely transmitted (Jabber (Bit A), out-of-window-colli-
sion (Bit 9), and 16Coll (Bit F) must all be clear). If TxOKiE (Register 7, TxCFG, Bit 8) is set,
there is an interrupt.
Out-of-Window
Jabber
This bit is set if a collision occurs more than 512 bit times after the first bit of the preamble. When
this occurs, the CS8900A forces a bad CRC and terminates the transmission. If Out-of-window-
iE (Register 7, TxCFG, Bit 9) is set, there is an interrupt
If the last transmission is longer than 26 msec, then the packet output is terminated by the jab-
ber logic and this bit is set. If JabberiE (Register 7, TxCFG, Bit A) is set, there is an interrupt.
#-of-TX-collisions These bits give the number of transmit collisions that occurred on the last transmitted packet.
Bit B is the LSB. If AnycolliE (Register 7, TxCFG, Bit B) is set, there is an interrupt when any
collision occurs.
16coll
This bit is set if the CS8900A encounters 16 normal collisions while attempting to transmit a
particular packet. When this happens, the CS8900A stops further attempts to send that packet.
If 16colliE (Register 7, TxCFG, Bit F) is set, there is an interrupt.
Reset value is: 0000 0000 0000 1000
Notes:
1.In any event register, like TxEvent, all bits are cleared upon readout. The host is responsible for
processing all event bits.
2.TxOK (Bit 8) and the Number-of-Tx-Collisions (Bits E-B) are used in normal packet transmission.All
other bits (6, 7, 9, A, and F) give the status of abnormal transmit operation.
4.4.11 Register 9: Transmit Command Status
(TxCMD, Read-only, Address: PacketPage base + 0108h)
7
6
5
4
3
2
1
0
TxStart
001001
F
E
D
C
B
A
9
8
TxPadDis
InhibitCRC
Onecoll
Force
This register contains the latest transmit command which tells the CS8900A how the next packet should be sent.
The command must be written to PacketPage base + 0144h in order to initiate a transmission. The host can read
the command from register 9 (PacketPage base + 0108h). See Section 5.6 on page 99.
001001
These bits provide an internal address used by the CS8900A to identify this as the Transmit
Command Register. When reading this register, these bits will be 001001, where the LSB cor-
responds to Bit 0.
TxStart
This pair of bits determines how many bytes are transferred to the CS8900A before the MAC
starts the packet transmit process.
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DS271F4
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