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C28343 control card ADS7865 ADC reading all zeros

Girish Ramachandran1
Prodigy 70 points

Other Parts Discussed in Thread: ADS7865, CONTROLSUITE

I have been using the C28343 control card with the DIM100 experimenter's kit for several months now. I have three setups with the same software running successfully on all of them. Recently I had to switch out the control cards and I cannot get the ADC to read proper values anymore. It simply returns all zeros on all channels. I am running in the psuedo diff mode. I have purchased three new control cards and they all do this straight out of the box. I even setup the control cards on an experimenter's kit independent of the rest of my system and ran it off of USB and over a Blackhawk USB 2000 JTAG controller, with the ADC example code and I see the same results. I have tried different emulators and it doesnt make a difference. I even tried running it off of a boot loader and it doesn't make a difference. 

I can see differences in silkscreen notation and ref des between some of the older control cards and the newer ones that I just purchased.

1. Any ideas on what is going on with these?

2. Are the schematics available on the website for the control card for v1.0 or v1.1 of the board? Are there any updated schematics available for this?

3. Is there some change to the common mode voltage supplied to the ADC in the newer control cards?

4. I noticed the ADS7865 have different part markings - is there a list of package marking and their meaning available somewhere?

Thanks

  • 0
    Prodigy 70 points

    An Update to this post - 

    I am using GPIO56 and GPIO57 tied to start convert on the ADC. Have these lines changed between versions of the control card?

    Girish

  • 0
    TI__Guru 60865 points

    Hi Girish,

    For 2) if you download ControlSUITE, you can find the schematics in \TI\controlSUITE\development_kits\~controlCARDs\DIM168CC2834xHWdevPkg

    it looks like the changes from v1.0 to v1.1 

    For 4) Usually the markings include some date/lot information, so some variation is to be expected.  I am not sure how to decode them for ADS7865.  Are there marking differences for the C28343?

    If this information isn't enough to debug the problem, I can help you debug further.

  • 0 in reply to Devin Cottier
    Prodigy 70 points

    Devin

    I am aware of the following two schematics for C28343 control cards - 

    1. C283XX_BH_CC_V)_!&_R1_1.pdf dated May 11, 2009

    2. CC2834x-DIM100_SCH_V0_11.pdf dated January 23, 2009

    Document 1 is consistent with "Example_2834xADC_XINTF_QuickStart_Guide.pdf" and corresponding example code that describes how to communicate with the ADS7865. The quick start guide details how you can use GPIO 56 and 57 to manually start convert pin of the ADC. Document 1 captures this in the schematics as well.

    However, Document 2 does NOT have the GPIO56 and 57 tied as options to the start convert pin of the ADC. The only option is to use the EXTSOC connection from the ePWM module.

    This is the problem. At some point a change was made to the control card hardware, but NONE of  the documents in the control suite were updated to reflect this. Only the schematics available under the control card page on the website  - which is document 2 - capture this change. 

    How do I which boards out of what I have are per schematics in Document 1 and which are per schematics in document 2?

    Girish

  • 0 in reply to Girish Ramachandran1
    TI__Guru 60865 points

    Girish,

    It looks like I sent you the updates for the wrong control card (DIM168 instead of DIM100).  Sorry about that. 

    I think document 1 is the most recent version (v1.1) and document 2 was an older version; I am not sure if we ever released control cards based on document 2. 

    Can you clarify which version of the control card is working and which is not? You mentioned there are differences in silk screen between the two, can you elaborate (or send a picture of one of each card).

    Have you concluded that the new cards do not work because GPIO56/GPIO57 are not present, or are you still trying to find the exact issue?

  • 0 in reply to Devin Cottier
    Prodigy 70 points

    Devin

    I purchased Delfino C28343 ControlCard part#; TMDSCNCD28343. If you download the hardware developers package off of the TI website it opens "sprc905.zip" which contains Document 2 - "CC2834x-DIM100_SCH_V0_11.pdf". If you look at this schematic GPIO 56/57 are NOT connected to the ADC. 

    If you look under ControlSuite "controlSUITE\development_kits\~controlCARDs\CC2834xHWdevPkg" it contains Document 1, which has GPIO56/57 connected to the ADC. 

     - Which is the correct document., i.e. schematic for the control card part# described above? What you stated in your latest post about document 1 being the latest is NOT consistent with what I am seeing on TI website. Please clarify. 

    - At this point, my best guess is GPIO56/57 not being connected is the issue. But I have not concluded this to be the case. 

    - Control card V1.0 and V1.1 have silkscreen differences. I had originally assumed that I might have had two different versions, but all six units that we have are v1.1 control cards. So this is NOT the issue. 

    Girish

  • 0 in reply to Girish Ramachandran1
    TI__Guru 60865 points

    Girish,

    In general, ControlSUITE will be more up to date.  This appears to be the case, as control suite has the schematics for control card V1.1 while the website has schematics for V0.11. Use the V1.1 schematics, since these match the boards you have.  

    Since your cards are V1.1 and the V1.1 schematic does include the GPIO56/GPIO57 connections, I think we can rule this out as a problem?

    Are all of the C28343 devices marked as TMS?  A difference between the cards could be if some devices are TMX (experimental).   

  • 0 in reply to Devin Cottier
    Prodigy 70 points

    Devin

    All the devices on the control cards are marked as TMS. 

    So, are you saying I should disregard the schematic on the TI website under that part # I gave you? 

    The symptom that I see is ADS7865 returns all zeros regardless of that the input is. Do you know under what cases will the ADC return this value?

    Girish

  • 0 in reply to Girish Ramachandran1
    TI__Guru 60865 points

    Girish,

    Yes, disregard that version of the schematic.  Use the version that matches your board version.  

    Have you investigated the signals being produced by the DSP that are going to the ADC (using a scope or logic analyzer)?   Can you post some code snippets that you are running that you expect to produce ADC readings? 

    Another option may be to post in the TI forum for ADS7865; I think you mentioned some differences in markings between cards.