Cirrus Logic CS8900A - Manual (Page 51)

DS271F5 51
CS8900A
Crystal LAN™ Ethernet Controller
CIRRUS LOGIC PRODUCT DATASHEET
4.4.3.4 Accept Bits
There are nine Accept bits located in the Rx-
CTL register (Register 5), each of which is fol-
lowed by the suffix A. Accept bits indicate
which types of frames will be accepted by the
CS8900A. (A frame is said to be “accepted” by
the CS8900A when the frame data are placed
in either on-chip memory, or in host memory
by DMA.) Four of these bits have correspond-
ing Interrupt Enable (iE) bits. An Accept bit and
an Interrupt Enable bit are independent opera-
tions. It is possible to set either, neither, or
both bits. The four corresponding pairs of bits
are:
If one of the above Interrupt Enable bits is set
and the corresponding Accept bit is clear, the
CS8900A generates an interrupt when the as-
sociated receive event occurs, but then does
not accept the receive frame (the length of the
receive frame is set to zero).
The other five Accept bits in RxCTL are used
for destination address filtering (see
Section 5.2.10 on page 87). The Accept
mechanism is explained in more detail in
Section 5.2 on page 78.
4.4.4 Status and Control Register Sum-
mary
The table on the following page (Table 16) pro-
vides a summary of the Status and Control
registers. Section 4.4.4 on page 51 gives a de-
tailed description of each Status and Control
register.
Interrupt Enable Bit
(register name)
Event Bit or Counter
(register name)
ExtradataiE (RxCFG) Extradata (RxEvent)
RuntiE (RxCFG) Runt (RxEvent)
CRCerroriE (RxCFG) CRCerror (RxEvent)
RxOKiE (RxCFG) RxOK (RxEvent)
16colliE (TxCFG) 16coll (TxEvent)
AnycolliE (TxCFG) “Number-of Tx-collisions”
counter is incremented
(TxEvent)
JabberiE (TxCFG) Jabber (TxEvent)
Out-of-windowiE (TxCFG) Out-of-window (TxEvent)
TxOKiE (TxCFG) TxOK (TXEvent)
SQEerroriE (TxCFG) SQEerror (TxEvent)
Loss-of-CRSiE (TxCFG) Loss-of-CRS (TxEvent)
MissOvfloiE (BufCFG) RxMISS counter over-
flows past 1FFh
TxColOvfloiE (BufCFG) TxCOL counter overflows
past 1FFh
RxDestiE (BufCFG) RxDest (BufEvent)
Rx128iE (BufCFG) Rx128 (BufEvent)
RxMissiE (BufCFG) RxMISS (BufEvent)
TxUnderruniE (BufCFG) TxUnderrun (BufEvent)
Rdy4TxiE (BufCFG) Rdy4Tx (BufEvent)
RxDMAiE (BufCFG) RxDMAFrame (BufEvent)
Table 15. Interrupt Enable Bits and Events
IE Bit in RxCFG A Bit in RxCTL
ExtradataiE ExtradataA
RuntiE RuntA
CRCerroriE CRCerrorA
RxOKiE RxOKA