Datasheet
TSB41BA3D
SLLS959A – DECEMBER 2008 – REVISED MARCH 2009 ...............................................................................................................................................
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Table 28 shows the encoding for the request type.
Table 28. Request Type Encoding
LR1 – LR4 NAME DESCRIPTION
0000 Reserved Reserved
0001 Immed_Req Immediate request. On detection of idle, the PHY arbitrates for the bus.
0010 Next_Even Next even request. The PHY arbitrates for the bus to send an asynchronous packet in the even fairness
interval phase.
0011 Next_Odd Next odd request. The PHY arbitrates for the bus to send an asynchronous packet in the odd fairness
interval phase.
0100 Current Current request. The PHY arbitrates for the bus to send an asynchronous packet in the current fairness
interval.
0101 Reserved Reserved
0110 Isoch_Req_Even Isochronous even request. The PHY arbitrates for the bus to send an isochronous packet in the even
isochronous period.
0111 Isoch_Req_Odd Isochronous odd request. The PHY arbitrates for the bus to send an isochronous packet in the odd
isochronous period.
1000 Cyc_Start_Req Cycle start request. The PHY arbitrates for the bus to send a cycle start packet.
1001 Reserved Reserved
1010 Reg_Read Register read request. The PHY returns the specified register contents through a status transfer.
1011 Reg_Write Register write request. Write to the specified register in the PHY.
1100 Isoch_Phase_Even Isochronous phase even notification. The link reports to the PHY that:
1) A cycle start packet has been received.
2) The link has set the isochronous phase to even.
1101 Isoch_Phase_Odd Isochronous phase odd notification. The link reports to the PHY that:
1) A cycle start packet has been received.
2) The link has set the isochronous phase to odd.
1110 Cycle_Start_Due Cycle start due notification. The link reports to the PHY that a cycle start packet is due for reception.
1111 Reserved Reserved
For a bus request, the length of the LREQ bit stream is 11 bits as shown in Table 29 .
Table 29. Bus Request
BIT(s) NAME DESCRIPTION
0 Start bit Indicates the beginning of the transfer (always 1)
1 – 4 Request type Indicates the type of bus request. See Table 28 .
5 Request format Indicates the packet format to be used for packet transmission. See Table 30 .
6 – 9 Request speed Indicates the speed at which the link sends the data to the PHY. See Table 31 for the encoding of this field.
10 Stop bit Indicates the end of the transfer (always 0). If bit 6 is 0, then this bit can be omitted.
Table 30 shows the 1-bit request format field used in bus requests.
Table 30. Bus Request Format Encoding
LR5 DATA RATE
0 Link does not request either Beta or legacy packet format for bus transmission
1 Link requests Beta packet format for bus transmission
Table 31 shows the 4-bit request speed field used in bus requests.
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