Datasheet

LLC Service Request
Each cell represents one clock sample period, and n is the number of bits in the request stream.
LR1
LR2 LR3 LR (n-2)LR0 LR (n-1)
TSB41BA3D
www.ti.com ............................................................................................................................................... SLLS959A – DECEMBER 2008 – REVISED MARCH 2009
The PHY initiates a transmit operation after winning control of the serial bus following a bus request by the LLC.
The transmit operation is initiated when the PHY grants control of the interface to the LLC.
Table 13 and Table 14 show the encoding of the CTL0 – CTL1 bus.
Table 13. CTL Encoding When PHY Has Control of the Bus
CTL0 CTL1 NAME DESCRIPTION
0 0 Idle No activity (this is the default mode)
0 1 Status Status information is being sent from the PHY to the LLC.
1 0 Receive An incoming packet is being sent from the PHY to the LLC.
1 1 Grant The LLC has been given control of the bus to send an outgoing packet.
Table 14. CTL Encoding When LLC Has Control of the Bus
CTL0 CTL1 NAME DESCRIPTION
0 0 Idle The LLC releases the bus (transmission has been completed).
1 Hold The LLC is holding the bus while data is being prepared for transmission or indicating that another packet
0
is to be transmitted (concatenated) without arbitrating.
1 0 Transmit An outgoing packet is being sent from the LLC to the PHY.
1 1 Reserved None
To request access to the bus, to read or write a PHY register, or to control arbitration acceleration, the LLC
sends a serial bit stream on the LREQ terminal as shown in Figure 13 .
Figure 13. LREQ Request Stream
The length of the stream varies depending on the type of request as shown in Table 15 .
Table 15. Request Stream Bit Length
REQUEST TYPE NUMBER OF BITS
Bus request 7 or 8
Read register request 9
Write register request 17
Acceleration control request 6
Regardless of the type of request, a start bit of 1 is required at the beginning of the stream, and a stop bit of 0 is
required at the end of the stream. The second through fourth bits of the request stream indicate the type of the
request. In the following descriptions, bit 0 is the most significant and is transmitted first in the request bit stream.
The LREQ terminal is normally low.
Copyright © 2008 – 2009, Texas Instruments Incorporated Submit Documentation Feedback 33
Product Folder Link(s): TSB41BA3D