CS8920A View Datasheet(PDF) - Cirrus Logic
Part Name
Description
MFG CO.
'CS8920A' PDF : 144 Pages View PDF
CS8920A
Register 8: Transmitter Event (TxEvent, Read-only)
Address: PacketPage base + 0128h
F
16coll
E
D
C
B
Number-of-Tx-collisions
A
Jabber
9
Out-of-
window
TxEvent gives the event status of the last packet transmitted.
8
TxOK
7
SQEerror
6
Loss-of-
CRS
5-0
001000
BIT NAME
DESCRIPTION
5-0 001000
These bits provide an internal address used by the CS8920A to identify this as the
Transmitter Event Register. When reading this register, these bits will be 001000, where
the LSB corresponds to Bit 0.
6
Loss-of-CRS If the CS8920A 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.
7
SQEerror
At the end of a transmission on the AUI, the CS8920A 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.
8
TxOK
This bit is set if the last packet was completely transmitted (Jabber (Bit A), out-of-
window-collision (Bit 9), and 16Coll (Bit F) must all be clear). If TxOKiE (Register 7,
TxCFG, Bit 8) is set, there is an interrupt.
9
Out-of-
window
This bit is set if a collision occurs more than 512 bit times after the first bit of the
preamble. When this occurs, the CS8920A forces a bad CRC and terminates the
transmission. If Out-of-windowiE (Register 7, TxCFG, Bit 9) is set, there is an interrupt.
A
Jabber
If the last transmission is longer than 26 ms, the packet output is terminated by the
jabber logic and this bit is set. If JabberiE (Register 7, TxCFG, Bit A) is set, there is an
interrupt.
E-B Number-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.
F
16coll
This bit is set when the CS8920A encounters 16 normal collisions while attempting to
transmit a particular packet. When this happens, the CS8920A stops further attempts to
send that packet. If 16colliE (Register 7, TxCFG, Bit F) is set, there is an interrupt.
This register’s initial state after reset 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.
DS238PP2
55
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