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ADS52J65: DEMOD 3-wire mode MISC 0x2E

HSato
Prodigy 30 points
Part Number: ADS52J65


< 2022.04.25  question started >

(1) For DEMOD Reg (90h - 9Fh), it seems that can't set to 3-wire mode by SPI readout.  Of cource we set SENZ1=0, SENZ2=0.

      We had been confirmed 3-wire readout for other registers.

　　Should it be possible to 3-wire mode for DEMOD Reg ?

(2) In MISC 0x2E  Register VCM_FINE_PROG readout, it indicates some unclear values apart from lower 3bit.

    The Reset value should be all 0.

    Please tell me this behavior.

< 2022.04.28  response from Abhishek >

1. With respect to 3-wire SPI mode, are you facing difficulty in writing to demod register or reading from demod register? or both?

Generally, before reading any register, you will have to make SPI_DIG_EN pin high (since read en is not in the demod page), then set the read en. After that, if you are accessing the demod register, you make SPI_DIG_EN =0 (same as SENZ1 = 0 , SENZ2 =0)

Could you please share your sequence of operations for me to verify?

2. It is possible that register 2E [15:3] might be coming from internal fuse. So it may contain some value apart from zero. The VCM_FINE_PROG bits should be correct, thats all.

Do you read the same value in the bits [15:3] all the time or the value is different on consecutive readouts.

< 2022.04.29  answer to Abhishek >


1. Could you see an attachment ? ( DEMOD Reg. R/W test ).
 I think it seems not working properly DEMOD Reg.( problem: writing and 3-wire mode reading. )

 I can't search 'SPI_DIG_EN' pin. what is this ? internal signal name ?

2. I can read same value from 2E so far.
 Are there possibility any failure ?  Or,  bit[15-3] Reset Value 0h is typo in the datasheet ?
  • 0
    TI__Expert 7130 points

    Hi Hiroto-san,

    1. The SPI_DIG_EN is the same signal as SENZ2. I am sorry for the confusion. We use this term in the new products but essentially it is control signal to access demodulator register page.

    I am exploring the document you shared and thinking about it. Please allow me some time to get back on the same.

    Regarding your other question:

    2. The register 2E is a fuse register used for trimming device performance during production. We program the trim values in this hence you are getting some data when you read it. the behaviour you are observing is totally expected. No need to worry about any failure concerns. 

    Thanks and regards,

    Abhishek

  • 0 in reply to Abhishek Vishwa1
    Prodigy 30 points

    Hello Abhishek san,

    I'm glad I got your answer today. and, I understood you supporting me.

    1. Regarding DEMOD reg:

      I 'd like to wait your investigation results.

    2. Regarding Register 2Eh:

      I understood as a parhaps typo of datasheet, and close this.

    Thank you for your help.

    Best regsards,

     H.Sato

  • 0 in reply to HSato
    TI__Expert 7130 points

    Hi Hiroto-san,

    Due to some work, I couldn't look at it. I will reply back to you by today evening.

    Thanks & regards,
    Abhishek

  • 0 in reply to Abhishek Vishwa1
    Prodigy 30 points

    Hello Abhishek san,

    Thanks to notification. I will be waiting.

    Best regards,
     H.Sato

  • 0 in reply to HSato
    TI__Intellectual 1590 points

    Hi Hiroto-San,

    Thanks for reaching out. While Abhishek is working on this issue, I might have few suggestions which you can try it out quickly.

    1) Demodulator block might not behave properly if demodulator is not enabled via spi. Can you confirm whether you are enabling demodulator block before checking 3-wire operation in 0x94 register?

    2) Can you try re-checking 3 Wire SPI operating after enabling demod using Reg 29h in 8-channel Digital page and see if it's working?

    Regards.

    Kalyan

  • 0
    Prodigy 30 points

    Hello Kalyan san,

    Thanks to your help.

    We are intending the following :
    (1) reg. 12h write : PAGE_SEL_8CH_DIG=1 (0x0002)
    (2) reg. 29h write : EN_DEMOD=1 (0x0001)
    (3) reg. 12h write : PAGE_SEL_8CH_DIG=0 (0x0000)
    However, not changed the circumstance for now.

      Also, we have done verify:
      (4) reg. 12h write: PAGE_SEL_8CH_DIG=1 (0x0002)
      (5) reg. 29h read : EN_DEMOD is 1 (0x0001)
      (6) reg. 12h write: PAGE_SEL_8CH_DIG=0 (0x0000)

    I have a little worry about the power of DEMOD reg.
    Is there any method good to check DEMOD power-on ?

    Best regards,
     H.Sato

  • 0 in reply to HSato
    TI__Intellectual 1590 points

    Hi Hiroto-san,

    I typically check for DVDD supply current whenever writing to Demodulator. Enabling features like decimation or down-conversion will increase the supply current. That's one way to check whether demodulator writes are working or not. If checking the supply currents is not possible on your setup, SPI readback is the only option.  Have you tried the SPI readback in simple 4 wire mode? Is it possible on your setup ?

    Abhishek-san is on leave for couple of days. I'll be helping you with this request meanwhile. Please give me some time till tomorrow to check both 3-wire and 4-wire mode on my hardware setup and get back to you. Thanks for your kind understanding.

    Regards,

    Kalyan

  • 0 in reply to Bellala Kalyan
    Prodigy 30 points

    Hello Kalyan san,

    Thank you for advice about supply-current,  maybe I'm grasp similar..
     I'm sorry it's difficult to explain well, I thought that DEMOD Reg-Power and DEMOD Reg registers are independadnt.

    So, we main probrelm is that can not set to 3 wire mode only for DEMOD Reg.
    Other registers can set to 3 wire mode.
    And, DEMOD Reg. values could be read by 4 wire mode.    Why ??
    ( I sent SPI_ADC_220428_1.pdf attach to this thread )

    Best regards,
     H.Sato

  • 0 in reply to HSato
    TI__Intellectual 1590 points

    Hiroto-san,

    Thanks for your explanation. I understand the issue better now. I'll update you with my experiment results soon.

    Regards,

    Kalyan

  • 0 in reply to Bellala Kalyan
    TI__Expert 7130 points

    Hi Hiroto-san,

    Sorry to keep you waiting to solve your issue.

    Currently I am also facing some issue in 3W-mode and I am in debug process. 

    Please allow me some time to fix the same and provide you resolution to your problem.

    Thanks & regards,

    Abhishek

  • 0 in reply to Abhishek Vishwa1
    Prodigy 30 points

    Hello Abhishek san,

    Long time no see.
     Are you in debugging for these matters?
    Any way, I'll be waiting your findings.
    Thanks to your help.

    Best regards,
     H.Sato

  • 0 in reply to HSato
    TI__Expert 7130 points

    Hi Hiroto-san,

    I was also facing the same issue as you.

    So I went back and looked at the digital implementation in the device.

    Seems like the 3-Wire SPI readout is not supported in the Demodulator registers. The internal FSM is very different in the demod block and it does not support 3Wire Mode. The demod register data comes on SDOUT pin only.

    I apologize for the inconvenience caused to you, I will get the datasheet updated with the correct information.

    I am closing this thread since we cannot support the 3W SPI in demod block.

    Thanks & regards,

    Abhishek