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DAC5687: Why can't I write into registers CONFIG0~CONFIG2 (0x01~0x03)

Masanori Tachibana
Genius 5350 points
Part Number: DAC5687

Hello support team,

Our customer is evaluating DAC5687 now.
The following phenomenon is occurring in customer's evaluation environment.

He can not write into three addresses of CONFIG0 (0x01), CONFIG1 (0x02), CONFIG2 (0x03).
Even if he wrote, the data of three addresses will be fixed with the value of the read data.
CONFIG0 (0×01): 0×80
CONFIG1 (0x02): 0x00
CONFIG2 (0x03): 0x00

He had confirmed that the other registers can be written and read.

Questions;
Is there possible reasons why he can not write into these three registers?
Are there any conditions necessary to write into these three registers?

Best regards,
M. Tachibana

  • 0
    TI__Guru* 91947 points

    Masanori,

    We are looking into this.

    Regards,

    Jim

  • 0
    TI__Mastermind 20541 points
    Hi M. Tachibana,

    Can you please ask customer to power up the device and do a read back for all the register and make sure he is reading the default value for all the registers mentioned in the datasheet. I haven't seen such and issue where you are able to write all the resister accepts the config0, config1 and config2. Has customer test just one device or is he seeing the issue on multiple devices?

    Regards,
    Neeraj
  • 0 in reply to Neeraj Gill
    Genius 5350 points
    Hello Neeraj-san,

    I'm sorry for the late reply.
    This phenomenon is confirmed on only one board. And now the customer is checking the another one.
    I received additional questions from the customer.
    These are confirmation just in case for the customer.

    1. Are there any restrictions on procedures of writing register data?

    2. The customer writes register data every 4 bytes. Are there any restriction on its method.

    3. Are there any problem with the connections of the following terminals?
    And do they affect the writing register data?
    PHSTR (pin 94) = H
    QFLAG (pjn 98) = H
    TESTMODE (pin 97) = L
    TXENABLE (pin 33) = H
    SLEEP (pin 96) = open

    4. In the DAC5687EVM circuit, PHSTR, QFLAG, TESTMODE, and TXENABLE have 49.9 Ω pull-down resistors.
    Is the value of these resistor meaningful?
    For example, is a pull-down resistor necessary if fixing to 'L'?

    Best regards,
    M. Tachibana
  • 0 in reply to Masanori Tachibana
    Genius 5350 points

    Hello Neeraj-san,

    Now I will inform you of additional information.
    The same phenomenon seems to be occurring also on another board.
    Therefore, the phenomenon that can not write to registers (0x01, 0x02 and 0x03) occurs with multiple devices.
    Please tell me if you have any possible advice.

    Best regards,
    M. Tachibana

  • 0 in reply to Masanori Tachibana
    TI__Mastermind 20541 points
    Hi M. Tachibana,

    Sorry for late reply. Is customer still seeing the problem? What frequency are running the to serial port? The MAX SCLK frequency is 10MHz. Also can you please ask to do 2 byte write instead of 4 byte write?

    Regards,
    Neeraj
  • 0 in reply to Neeraj Gill
    Genius 5350 points

    Hello Neeraj-san,

    Thank you for your kind support.
    The problem that the customer could not write into CONFIGx registers had been solved.

    The customer was writing every 4 bytes. But the address specification and the order of data was incorrect.
    We advised the customer to correct these, the customer have been able to write data correctly.
    Thank you for your cooperation.

    Best regards,
    M. Tachibana