CS8900A
Crystal LAN™ Ethernet Controller
5.2.2.1 Configuring the Physical Interface
Register 5, RxCTL
Operation
Bit Bit Name
Configuring the physical interface consists of
determining which Ethernet interface should
be active, and enabling the receive logic for
serial reception. This is done via the LineCTL
register (Register 13) and is described in
Table19.
A
IndividualA When set, frames with DA that
matches the IA at PacketPage base
+ 0158h are accepted*.
B
Broad- When set, all broadcast frames are
castA
accepted*.
C CRCerrorA When set, frames with bad CRC that
pass the DA filter are accepted.
Register 13, LineCTL
D
RuntA
When set, frames shorter than 64
bytes that pass the DA filter are
accepted.
Bit
6
Bit Name
Operation
SerRxON When set, reception enabled.
8
AUIonly
When set, AUI selected (takes
precedence over AutoAUI/10BT).
E ExtradataA When set, frames longer than 1518
bytes that pass the DA filter are
accepted (only the first 1518 bytes
are buffered).
9
AutoAUI/10BT When set, automatic interface
selection enabled. When both bits
8 and 9 are clear, 10BASE-T
selected.
* Must also meet the criteria programmed into bits 8, C, D, and E.
Table 20. Frame Acceptance Criteria
E
LoRx Squelch When set, receiver squelch level
reduced by approximately 6 dB.
5.2.2.3 Selecting which Events Cause Inter-
rupts
Table 19. Physical Interface Configuration
The RxCFG register (Register 3) and the
BufCFG register (Register B) are used to de-
termine which receive events will cause inter-
rupts to the host processor. Table 22
describes the interrupt enable (iE) bits in these
registers.
5.2.2.2 Choosing which Frame Types to Ac-
cept
The RxCTL register (Register 5) is used to de-
termine which frame types will be accepted by
the CS8900A (a receive frame is said to be
"accepted" when the frame is buffered, either
on chip or in host memory via DMA). Table 20
describes the configuration bits in this register.
Refer to Section 5.2.10 on page 87 for a de-
tailed description of Destination Address filter-
ing.
Register 3, RxCFG
Bit Bit Name
Operation
8
RxOKiE When set, there is an interrupt if a
frame is received with valid length
and CRC*.
C CRCerroriE When set, there is an interrupt if a
frame is received with bad CRC*.
Register 5, RxCTL
D
RuntiE
When set, there is an interrupt if a
frame is received that is shorter than
64 bytes*.
Bit Bit Name
Operation
6
IAHashA When set, Individual Address frames
that pass the hash filter are
accepted*.
E ExtradataiE When set, there is an interrupt if a
frame is received that is longer than
1518 bytes*.
7
8
Promis When set, all frames are accepted*.
cuousA
* Must also pass the DA filter before there is an interrupt.
RxOKA When set, frames with valid length
and CRC and that pass the DA filter
are accepted.
Table 21.
5.2.2.4 Choosing How to Transfer Frames
9
MulticastA When set, Multicast frames that pass
the hash filter are accepted*.
The RxCFG register (Register 3) and the Bus-
CTL register (Register 17) are used to deter-
* Must also meet the criteria programmed into bits 8, C, D, and E.
Table 20. Frame Acceptance Criteria
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