Re: [802.3_ISAAC] [EXTERNAL] Re: [802.3_ISAAC] Question on Baseline Text Proposal for TDD Based 802.3dm PHY
Hi, Ragnar,
Thank you for raising this question. The tx_mode is from the PMA/PHYC and it tells the PCS what is the current transmit mode ( SEND_TS, SEND_TA, SEND_TA_EXT, SEND_N and SEND_Z). The non SEND_Z mode representing the corresponding repeating TDD ON/OFF cycles in symmetric training, asymmetric training, extended asymmetric training and data mode. It does not contain the specific transmit modulation/speed information, as well as TDD ON/OFF duration, etc. It reflects a general PHYC state.
pcs_tx_mode(TBD) is a pcs internal variable, which tells PCS what signals to send out to PMA at each symbol time (tx_symb). It controls modulation, speed, TX ON/OFF cycles durations.
When tx_mode=SEND_TS, this is the symmetric training mode, the pcs_tx_mode will alternate between T_2p5G and QUIET, to generate symmetric training TDD ON/OFF cycles. When it is T_2p5G, PCS will transmit 3Gsps PAM2 training frames. When it is QUIET, PCS will send zero.
When tx_mode=SEND_TA, this is asymmetric training mode, the pcs_tx_mode will alternate between T_PAM2 and QUIET, to generate PAM 2 asymmetric training TDD ON/OFF cycles. When it is T_PAM2, the 100M+MultiGBASE-T1/V1 will send 3Gsps PAM2 training frames. The 2.5G+100MBASE-T1/V1 will send 3Gsps PAM2 training frames. While the 5G/10G+100MBASE-T1/V1 will send 6Gsps PAM2 training frames.
When tx_mode=SEND_TA_EXT, this is the asymmetric extended training mode only used for 10G+100MBASE-T1/V1 and 100M+10GBASE-T1/V1, the pcs_tx_mode will alternate between T_PAM2_4 and QUIET. For 100M+10GBASE-T1/V1, T_PAM2_4 will send 3Gsps PAM2 training frames. For 10G+100MBASE-T1/V1, T_PAM2_4 will send 6Gsps PAM2(during Refresh header) and PAM4 (during training payload).
Hope this clarifies your question. Thanks.
Wei
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