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Ixiasoft
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Ixiasoft
2.1.7. Deskew Logic
Whe multiple steams ae boded togethe, the skew betwee multiple EMIB itefaces must be emoved. The F-tile PMA Diect ad FEC Diect IPs automatically compesate fo the skew betwee multiple EMIB itefaces without the eed fo itevetio.
TX Deskew Logic
Oce bodig is eabled, deskew logic i the tasmit diectio aligs the EMIB iteface by geeatig iteal deskew pulses evey 16 o 32 clock cycles (depedig o vaiat cofiguatio) fo all TX EMIB itefaces. These pulses ae used to alig the tasmit paallel data befoe isetio ito the PMA. This logic is geeated fo all IP modes.
RX Deskew Logic
Oce bodig is eabled, optioal deskew logic i the eceive diectio aligs the EMIB iteface based o deskew pulses eceived i the RX data. I PMA Diect mode, this optioal RX deskew is implemeted fo PAM4 mode whe the umbe of EMIB itefaces pe PMA is geate tha oe. I PMA Diect mode, the deskew logic opeates o EMIB itefaces associated with each PMA idepedetly. Fo example, fo a 2-lae PMA Diect vaiat, the deskew logic deskews the EMIB itefaces fo Lae 1 idepedetly fom the EMIB itefaces fo Lae 2. I FEC Diect mode, this optioal RX deskew is implemeted whe the total umbe of EMIB itefaces is geate tha oe. I FEC Diect Mode, the RX deskew logic aligs all the EMIB itefaces togethe. Fo example, fo a 2-lae FEC Diect vaiat, the deskew logic deskews the EMIB itefaces fo Lae 1 togethe with the EMIB itefaces fom Lae 2. Wheeve RX deskew is eabled, all x_coeclki iputs ae expected to be dive by the same souce. The RX Deskew logic ca deskew up to five x_coeclki cycles.
Whe opeatig i NRZ mode with o RS-FEC, deskew logic is always disabled.
I the RX diectio, whe opeatig i eithe PAM4 mode o FEC Diect Mode, deskew logic ca be tued o with Eable RX de-skew whe available paamete i the IP paamete edito. If the cuet cofiguatio does ot suppot RX de-skew, the paamete edito displays a ifomatio message duig geeatig idicatig that RX deskew is ot suppoted fo the cuet cofiguatio.
Whe the deskew logic is disabled, you must deskew the x_paallel_data buses comig out of each EMIB based o the RX deskew pulses povided by the IP. These deskew pulses appea o x_paallel_data[78] whe the PMA is i double data width mode ad x_paallel_data[36] whe the PMA is i sigle width mode.
The followig figue shows sample behavio o x_paallel_data i sigle width mode befoe ad afte e-aligmet.