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Re: [802.3_ISAAC] [EXTERNAL] Re: [802.3_ISAAC] Question on Baseline Text Proposal for TDD Based 802.3dm PHY

Hi Wei Lou,

 

Thank you for your prompt reply. Your explanation makes sense to me.

 

I agree with George, that it might help to select better naming. For example, if the “training_active” variable would have been named something like “timer_active”, then I would have understood better the purpose of the variable.

 

I have another question related to the state diagram: How is the tx_tdd_active variable used differently from the tx_mode variable?

It looks to me like tx_tdd_active is always equal to tx_mode!=SEND_Z, and therefore it holds no information that is not already captured by tx_mode. Am I misunderstanding something here?

 

Ragnar

 

From: George Zimmerman <george@xxxxxxxxxxxxxxxxxxxx>
Sent: Thursday, July 3, 2025 7:52 AM
To: STDS-802-3-ISAAC@xxxxxxxxxxxxxxxxx
Subject: [EXTERNAL] Re: [802.3_ISAAC] Question on Baseline Text Proposal for TDD Based 802.3dm PHY

 

Wei Lou -thank you for the response, this is the kind of thing that is usually helped by having the variable, timer, and function definitions along with the state diagram. I see them for the PCS diagrams on page 32, but did I miss these definitions

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Wei Lou -thank you for the response, this is the kind of thing that is usually helped by having the variable, timer, and function definitions along with the state diagram.  I see them for the PCS diagrams on page 32, but did I miss these definitions for the PHY control state diagram?
 
Also, I might recommend for clarity to consider variable names carefully.  Particularly, I noticed you're using the name 'link_fail_inhibit_timer' which is widely used and understood in 802.3 as associated with autonegotiation.  You might consider a different name to be specific for the TDD training link monitor, which seems to be the use here.
 
George Zimmerman, Ph.D.
President & Principal
CME Consulting, Inc.
Experts in Advanced PHYsical Communications
george@xxxxxxxxxxxxxxxxxxxx
310-920-3860
 
-----Original Message-----
From: Wei Lou <000047a3c8c56bbe-dmarc-request@xxxxxxxxxxxxxxxxx> 
Sent: Wednesday, July 2, 2025 10:37 PM
To: STDS-802-3-ISAAC@xxxxxxxxxxxxxxxxx
Subject: Re: [802.3_ISAAC] Question on Baseline Text Proposal for TDD Based 802.3dm PHY
 
Hi, Ragnar,
Thank you for carefully reviewing TDD baseline text proposal. It is a valid question. Let me clarify the purpose of training_active signal. It is basically not a control signal to tell Master/Slave to start training. Rather, it is a flag which is used to indicate whether to start link_inhibit_timer. When link_inhibit_timer is started once, training_active will also be set to '1', and next time, the PHY won't enter the following if {} 
 
if(training_active=0 & detect_lp_burst)
   {training_active<=1
   start link_inhibit_timer}
 
This will avoid the case link_inhibit_timer is repeatedly restarted.
 
In our proposal, MASTER link_inhibit_timer is started when Master detects the 1st link partner burst( detect_lp_burst=1). While SLAVE link_inhibit_timer is started upon it enters TRAINING0 state (its detect_lp_burst is already set by detecting MASTER burst). While in TRAINING0 state, both master and slave will only start link_inhibit_timer once, then because training_active is set to '1', the if{} will not be satisfied anymore.
 
The actual SLAVE training starts during the SLAVE SILENT0 state. SLAVE stays SILENT0 until it trains its receiver and achieves synchronization/equalization, and set is loc_rcvr_status0=OK. At this time, SLAVE enters TRAINING0 state and sends its 1st burst/quiet cycle. 
 
Hope this answers your question. Thank you.
 
Wei
 
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