HC4GX15 Datasheet, PDF (429/668 Pages) Altera Corporation – HardCopy IV Device Handbook

Chapter 1: HardCopy IV GX Transceiver Architecture
Functional Modes
1–165
Table 1–46. GIGE Ordered Sets (Part 2 of 2)
Code
Ordered Set
Number of Code
Groups
/I1/
IDLE 1
2
/I2/
IDLE 2
2
Encapsulation
—
/R/
Carrier_Extend
1
/S/
Start_of_Packet
1
/T/
End_of_Packet
1
/V/
Error_Propagation
1
Note to Table 1–46:
(1) Two data code groups representing the Config_Reg value.
Encoding
/K28.5/D5.6
/K28.5/D16.2
—
/K23.7/
/K27.7/
/K29.7/
/K30.7/
Idle Ordered-Set Generation
The IEEE 802.3 specification requires the GIGE PHY to transmit idle ordered sets (/I/)
continuously and repetitively whenever the GMII is idle. This ensures that the
receiver maintains bit and word synchronization whenever there is no active data to
be transmitted.
In GIGE functional mode, any /Dx.y/ following a /K28.5/ comma is replaced by the
transmitter with either a /D5.6/ (/I1/ ordered set) or a /D16.2/ (/I2/ ordered set),
depending on the current running disparity. The exception is when the data following
the /K28.5/ is /D21.5/ (/C1/ ordered set) or /D2.2/ (/C2/) ordered set. If the
running disparity before the /K28.5/ is positive, an /I1/ ordered set is generated. If
the running disparity is negative, a /I2/ ordered set is generated. The disparity at the
end of a /I1/ is the opposite of that at the beginning of the /I1/. The disparity at the
end of a /I2/ is the same as the beginning running disparity (right before the idle
code). This ensures a negative running disparity at the end of an idle ordered set. A
/Kx.y/ following a /K28.5/ is not replaced.
1 Note that /D14.3/, /D24.0/, and /D15.8/ are replaced by /D5.6/ or /D16.2/ (for
/I1/, /I2/ ordered sets). /D21.5/ (part of the /C1/ order set) is not replaced.
Figure 1–133 shows the automatic idle ordered set generation.
Figure 1–133. Automatic Ordered Set Generation
clock
tx_datain [ ]
K28.5 D14.3 K28.5
D24.0
K28.5 D15.8
K28.5 D21.5
Dx.y
tx_dataout
Dx.y
K28.5
D5.6
K28.5 D16.2 K28.5
D16.2 K28.5
D21.5
Ordered Set
/I1/
/I2/
/I2/
/C2/
Reset Condition
After de-assertion of tx_digitalreset, the GIGE transmitter automatically
transmits three /K28.5/ comma code groups before transmitting user data on the
tx_datain port. This could affect the synchronization state machine behavior at the
receiver.
© June 2009 Altera Corporation
HardCopy IV Device Handbook Volume 3