Datasheet

TSB12LV32 Data Formats
76
SGLS139B − October 2003 − Revised April 2004TSB12LV32-EP
7.3 Phy Configuration
The format of the Phy configuration packet is shown in Figure 7−10 and is described in Table 7−7. The Phy
configuration packet transmit contains two quadlets, which are loaded into the ATF. The first quadlet is written
to address 50h. The second quadlet is written to address 58h. The 00E0h in the first quadlet (bits 16−31) tells
the TSB12LV32 that this quadlet is the Phy configuration packet. The 00E0h is then replaced with 0000h
before the packet is transmitted to the Phy interface.
3210 765411109815141312 1918 20 21 31302928272625242322
00 root_ID TR gap_cnt 0 0 0 0000011100
Logical inverse of first 16 bits of first quadlet 1111 1111111111
tcode = 00E0
000
1716
11
Figure 7−10. Phy Configuration Packet Format
The Phy configuration packet can perform the following functions:
• Set the gap count field of all nodes on the bus to a new value. The gap count, if set intelligently, can
optimize bus performance.
• Force a particular node to be the bus root after the next bus reset.
It is not valid to transmit a Phy configuration packet with both the R bit and T bit set to zero. This would cause
the packet to be interpreted as an extended Phy packet.
Table 7−7. Phy Configuration Packet Functions
FIELD NAME DESCRIPTION
00 The 00 field is the Phy configuration packet identifier.
root_ID The root_ID field is the physical_ID of the node to have its force_root bit set (only meaningful when R is set).
R When R is set, the force-root bit of the node identified in root_ID is set and the force_root bit of all other nodes are cleared.
When R is cleared, root_ID is ignored.
T When T is set, the PHY_CONFIGURATION.gap_count field of all the nodes is set to the value in the gap_cnt field.
gap_cnt The gap_cnt field contains the new value for PHY_CONFIGURATION.gap_count for all nodes. This value goes into effect
immediately upon receipt and remains valid after the next bus reset. After the second reset, gap_cnt is set to 63h unless a new
Phy configuration packet is received.
The format of a received Phy-configuration packet is shown in Figure 7−11 and is described in Table 7−8.
When PHY_PKT_ENA (bit 3 of the control register at 08h) is set, all Phy packets are received in the GRF. One
HDRERR interrupt is generated for every Phy packet received.
3210 765411109815141312 1918 20 21 31302928272625242322
00 numofQuadlets ackCode 0000spd00
Phy configuration quadlet
000
1716
Logical inverse of the Phy configuration quadlet
Figure 7−11. Receive Phy Configuration Packet Format
Table 7−8. Receive Phy Configuration Packet
FIELD NAME DESCRIPTION
numofQuadlets Total number of quadlets in the packet. This field is equal to 2 in this case.
ackCode This 5-bit field holds the acknowledge code sent by the receiver for the current packet. In this case, the ackCode is equal to 1
(ack_complete).
spd The spd field indicates the speed at which the current packet was sent. In this case, the spd field is equal to 00 (S100).