Datasheet
SLLS424G − JUNE 2000 − REVISED DECEMBER 2004
22
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
Table 2. Base Register Field Descriptions
FIELD SIZE TYPE DESCRIPTION
Physical ID 6 Rd This field contains the physical address ID of this node determined during self-ID. The physical ID is invalid
after a bus reset until self-ID has completed as indicated by an unsolicited register-0 status transfer.
R 1 Rd Root. This bit indicates that this node is the root node. The R bit is reset to 0 by bus reset, and is set to 1
during tree-ID if this node becomes root.
CPS 1 Rd Cable-power status. This bit indicates the state of the CPS input terminal. The CPS terminal is normally tied
to serial bus cable power through a 400-kΩ resistor. A 0 in this bit indicates that the cable power voltage
has dropped below its threshold for assured reliable operation.
RHB 1 Rd/Wr Root-holdoff bit. This bit instructs the PHY to attempt to become root after the next bus reset. The RHB bit
is reset to 0 by hardware reset and is unaffected by bus reset.
IBR 1 Rd/Wr Initiate bus-reset. This bit instructs the PHY to initiate a long (166 µs) bus reset at the next opportunity. Any
receive or transmit operation in progress when this bit is set completes before the bus reset is initiated. The
IBR bit is reset to 0 by hardware reset or bus reset.
Gap_Count 6 Rd/Wr Arbitration gap count. This value is used to set the subaction (fair) gap, arb-reset gap, and arb-delay times.
The gap count may be set either by a write to this register or by reception or transmission of a PHY_CONFIG
packet. The gap count is set to 3Fh by hardware reset or after two consecutive bus resets without an
intervening write to the gap count register (either by a write to the PHY register or by a PHY_CONFIG
packet).
Extended 3 Rd Extended register definition. For the TSB41AB2 this field is 111b, indicating that the extended register set
is implemented.
Num_Ports 5 Rd Number of ports. This field indicates the number of ports implemented in the PHY. For the TSB41AB2 this
field is 2.
PHY_Speed 3 Rd PHY speed capability. For the TSB441AB2 PHY this field is 010b, indicating S400 speed capability.
Delay 4 Rd PHY repeater data delay. This field indicates the worst case repeater data delay of the PHY, expressed as
144+(delay × 20) ns. For the TSB41AB2 this field is 0.
LCtrl 1 Rd/Wr Link-active status control. This bit is used to control the active status of the LLC as indicated during self-ID.
The logical AND of this bit and the LPS active status is replicated in the L field (bit 9) of the self-ID packet.
The LLC is considered active only if both the LPS input is active and the LCtrl bit is set.
The LCtrl bit provides a software controllable means to indicate the LLC active status in lieu of using the LPS
input. The LCtrl bit is set to 1 by hardware reset and is unaffected by bus reset.
NOTE: The state of the PHY-LLC interface is controlled solely by the LPS input, regardless of the state of
the LCtrl bit. If the PHY-LLC interface is operational as determined by the LPS input being active, then
received packets and status information continues to be presented on the interface, and any requests
indicated on the LREQ input is processed, even if the LCtrl bit is cleared to 0.
C 1 Rd/Wr Contender status. This bit indicates that this node is a contender for the bus or isochronous resource
manager. This bit is replicated in the c field (bit 20) of the self-ID packet. This bit is set to the state specified
by the C/LKON input terminal upon hardware reset and is unaffected by bus reset.
Jitter 3 Rd PHY repeater jitter. This field indicates the worst case difference between the fastest and slowest repeater
data delay, expressed as (JITTER+1) × 20 ns. For the TSB41AB2 this field is 0.
Pwr_Class 3 Rd/Wr Node power class. This field indicates this node’s power consumption and source characteristics, and is
replicated in the pwr field (bits 21–23) of the self-ID packet. This field is set to the state specified by the
PC0–PC2 input terminals upon hardware reset and is unaffected by bus reset (see Table 9).