TSB12C01APZ datasheet(20/59 Pages) TI

20 / 59 page

3–4

Table 3–3. Control-Register Field Descriptions (Continued)

BITS

ACRONYM

FUNCTION NAME

DESCRIPTION

2–4

BsyCtrl

Busy control

These bits control which busy status (as described in IEEE 1394-1995

standard, the chip returns to incoming packets. The field is defined as

follows:

000 = follow normal busy/retry protocol, only send busy when

necessary.

001 = send busyA when it is necessary to send a busy acknowledge.

010 = send busyB when it is necessary to send a busy

acknowledge.

011 = reserved

100 = send a busy acknowledge to all incoming packets following the

normal busy/retry protocol.

101 = send a busy acknowledge to all incoming packets by sending

a busyA acknowledge.

110 = send a busy acknowledge to all incoming packets by sending

a busyB acknowledge.

111 = reserved

When retry_X is received and the receiving node needs to send a busy

acknowledge signal, it sends an ack_busy_X signal.

TxEn

Transmitter enable

When TxEn is cleared, the transmitter does not arbitrate or send

packets.

RxEn

Receiver enable

When RXEn is cleared, the receiver does not receive any packets.

PSBz

Physical DMA

busy

When:

1) PSOn is set,

2) PSRO is cleared or the incoming packet is a read,

3) destination offset is in the lower 4 Gbytes, and

4) PSBz is set,

the TSB12C01A sends a busy acknowledge to the incoming packet.

PSOn

Physical DMA on

When PSOn is set, the TSB12C01A uses PSRO and PSBz to determine

acceptance of incoming request packets addressed to the lower

4 Gbytes of initial memory space.

PSRO

Physical DMA read

only

When PSOn is set, the TSB12C01A uses PSRO to determine the

acceptance of incoming write request packets addressed to the lower

4 Gbytes of initial memory space.

RstTx

Reset transmitter

When RstTx is set, the entire transmitter resets synchronously. This bit

clears itself.

RstRx

Reset receiver

When RstRx is set, the entire receiver resets synchronously. This bit

clears itself.

12 – 15

BlkBusDep

Block bus-

dependent

address

This field is used by the receiver to filter out broadcast packets to the

bus-dependent area of CSR space. Setting the LSB of this field disables

the reception of broadcast packets to the lowest 128 bytes of

bus-dependent CSR space. Setting the MSB of this field disables the

reception of broadcast packets to the highest 128 bytes of

bus-dependent CSR space.

16 – 17

ATRC

AT retry code

This field contains the last retry code received. This code is logically

ORed with the retry code field (00) in the transmit packet, and the packet

is resent. This alleviates the need to change the retry code in the transmit

packet. The retry encoding follows the IEEE 1394-1995 standard. The

retry code is as follows:

retry_o (new)

retry_X

retry_A

retry_B

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