SBPH400-3 datasheet(13/43 Pages) STMICROELECTRONICS

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SBPH400-3

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Figure 2.4

PHY configuration packet format

The fields in the PHY configuration packet are interpreted as shown in Table 2.2.

Note that either or both of R and T must be set to 1.

2.7.5 Ping packet

The SBPH400 supports the use of ping timing. The ping packet has the format shown in Figure

2.5:

Figure 2.5

Ping packet format

When the SBPH400 receives a ping packet from the bus or from the local link addressed to

the node, it responds immediately (without arbitration) with a Self_ID packet to both the bus

and the local link.

2.7.6 Remote Access and Reply

The SBPH supports remote access to its internal registers. On receipt of a remote access

packet addressed to the node (either from the bus or from the local link), the SBPH400 will

immediately respond with the appropriate remote reply packet. The remote access packet and

the reply packet are also forwarded to the local link.

Table 2.2

PHY configuration packet fields

Field

Definition

Comment

root_ID

physical ID

the physical node identifier of the node to become root on next reset

set root

The Force_Root bit in the SBPH400 is set if R=1 and root_ID = the

node_ID of this node

set gap count

If T=1, then the value of the gap count register in the SBPH400 is set

to gap_cnt.

gap_cnt

Gap_Count value

new value of Gap Count register

0 0

root_ID

logical inverse of first quadlet

0000

gap_cnt

0 0

phy_ID

logical inverse of first quadlet

0000

type (0)

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