CS89712 datasheet(119/170 Pages) CIRRUS

119 / 170 page

CS89712

DS502PP2

119

3.18.4

Receiver Control Register (RxCTL, address offset 104h)

RxCTL has two functions: Bits 8, C, D, and E define what types of frames to accept. Bits 6, 7, 9, A, and B configure

the Destination Address filter. See Section 2.32.7,

“Receive Ethernet Port Locations”.

After reset, if no EEPROM is found by the CS89712, then the register has the following initial state. If an EEPROM

is found, then the register’s initial value may be set by the EEPROM. See Section 2.32.7,

“Receive Ethernet Port

Locations”.

Reset value is: 0000 0000 0000 0101

Notes: 1. Typically, when bits CRCerrorA, RuntA and ExtradataA are cleared (meaning bad frames are being

discarded), then the corresponding bits CRCerroriE, RuntiE and ExtradataiE should be set in register 3

(Receiver Configuration register) to allow the device driver to keep track of discarded frames.

5:0

PromiscuousA

IAHashA

000101

ExtradataA

RuntA

CBA

CRCerrorA

BroadcastA

IndividualA

MulticastA

RxOKA

Bit

Description

5:0

000101: These bits provide an internal address used by the CS89712 to identify this as register

5, the Receiver Control Register. For a received frame to be accepted, the Destination

Address of that frame must pass the filter criteria found in Bits 6, 7, 9, A, and B (see Section

2.32.7,

“Receive Ethernet Port Locations”).

IAHashA: When set, receive frames are accepted when the Destination Address is an Individ-

ual Address that passes the hash filter.

PromiscuousA: Frames with any address are accepted when this bit is set.

RxOKA: When set, the CS89712 accepts frames with correct CRC and valid length (valid

length is: 64 bytes <= length <= 1518 bytes).

MulticastA: When set, receive frames are accepted if the Destination Address is an Multicast

Address that passes the hash filter.

IndividualA: When set, receive frames are accepted if the Destination Address matches the

Individual Address found at Ethernet Port offset address 0158h to 015Dh.

BroadcastA: When set, receive frames are accepted if the Destination Address is FFFF FFFF

FFFFh.

CRCerrorA: When set, receive frames that pass the Destination Address filter, but have a bad

CRC, are accepted. When clear, frames with bad CRC are discarded. See Note 1.

RuntA:When set, receive frames that are smaller than 64 bytes, and that pass the Destination

Address filter are accepted. When clear, received frames less that 64 bytes in length are dis-

carded. The CS89712 discards any frame that is less than 8 bytes. See Note 1.

ExtradataA: When set, receive frames longer than 1518 bytes and that pass the Destination

Address filter are accepted. The CS89712 accepts only the first 1518 bytes and ignores the

rest. When clear, frames longer than 1518 bytes are discarded. See Note 1.

Table 69. Receiver Control

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