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Other Parts Discussed in Thread: TMS320C54V90

I have an old TI V.90 analog modem design based upon a TMS320C54V90 and a Si3016 DAA.

The design has worked well in the past and I have only recently encountered problems. I control the V.90 via AT commands across a serial port.

My problem situation is described in the steps below :

       --Modem sees and incoming call and relays RING message to DTE

       --DTE issues ATA command to answer incoming call

       --Modem appears to go off-hook for less than one second, then returns to on-hook. This is verified with an external monitor, as the modem still thinks it is off-hook.

       --If I monitor the audio, no answer tones are ever heard from the modem. I can call in from a hand-set and get nothing after the modem picks up.

       --After about a 20 second timeout (about the time for a train-up session) the modem returns a 'NO CARRIER' message and the call terminates.

Questions are :

      --What would make the modem not put out an answer tone ?

      --Could the DAA be dropping the analog call because of some over-voltage or over-current condition?

      --If the DAA does do above, can I get a status indicator of the event via some AT command?

  • John,

    I hate to say this but I am having a hard time to find out right contact for the C54V90. Let me keep trying but so far no luck. 

    Anyone in this forum can help John?


    Peter Chung


  • Peter:  I used to support customer applications on this device in the past, so I know the history on this. I can say unlike our other C54CST (Client side Telephony) which you can do a lot with including to operate in flex mode in addition to chipset mode, the C54V90 was canned (fixed) modem implementation solution of our  C54X dsp with V90 software developed by 3rd party company and ROM coded on chip. For modem related questions, they used to go to Titan the software developer.  What ROM code the chip has. The latest one we had was ROM_A3. You can read the marking on the chip. I suspect your issues could be something other than Framework or software.

    Is this development board or finished product that is failing. How many you have boards are exhibiting this issue? Look for anything changed to cause this problem.

    No Carrier or no tone, this means invalid command or illegal parameters are detected when you issued the AT command. These cpmplete commands listing, description, and thier errors are listed in Table 16 from the C54V90 Data sheet.




  • This design has been in a variety of products for quite a few years with no issues of this type until recently.

    One item I did note was the setting of country code with AT*Y162K=CC. My original DTE code did not perform this as the first step in initialization as recommended in the data-sheet, but sometime after a few other inits. I realized after some testing that the ATE0 I issued to turn echo off, was being over-ridden by a AT*Y162K=CC country code command. I moved this command to the very first item and it seems to have an impact on the issue, but I still have other sites which report problems even with this change.

    As for ROM version on the chip. My chip is marked : 




    I might expect an error message for an invalid command or illegal parameter, but I do not get any such message.

    The DTE host which control the modem has been using the same AT commands for many years without problem. So if something has changed recently, it my be in the timing of the DTE interface but not the commands or order of commands used via the DTE. (Noted exception in recent change for country code.)

    The country code change I detailed above 'seems' to have affected the issue with products I have access to locally. Testing continues.

    My remaining issues are with products in the field, and I do not have easy access to them. That is why I am looking for info to return from the V90 device to diagnose.

  • John: From the marking you sent, it looks like you have older silicon manufactured in 2004. This leads to believe you may have ROM_A1   This is an educated guess and  I still would need to check on that.


    From my days of supporting this device, I can remember the following:

     C54V90 (Rom_A2) it supports Caller ID I for Americas only.

    The C54V90A (ROM_A3) support Called ID I for Americas and Europe.  It does not support called ID II for either region.  there are other fetures and detials on this.

    Because of the troubleshooting nature of the issue, is there a way to contact you to get phone # so I can call you.  I would love to discuss the issue interactively. Then, we can update this post later.





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