AnsweredAssumed Answered

Issues in Analog Controller ADuCM361 (24-bit ADC controller)

Question asked by SaiJagini on Aug 27, 2015
Latest reply on Sep 4, 2015 by MMA

We are using ADuCM361 evaluation board(24-bit ADC controller - Analog make) for Accurate analog readings in our sensor interface circuits. In this we are getting following Problems.

Problems with ADC:
    1. If we left the ADC Channel for floating, then we are getting some garbage count rather than zero count.
    2. Even though we apply 0V (By Shorting of Channels) differentially to the ADC channels, we are getting variable output voltage as in terms of uVs (Maximum 11 uV).

    For this,we configured ADC with following setting:
        1.Internal Ref(1.2V).
        2.Averaging Factor = 14.
        3.Decimation Factor = 8.
        4.Chop - ON.
        5.Sinc3 - ON.

    Note: In firmware, we have used the Standard Driver files which are available in the home page of Analog Devices website.
               In Hardware, we have Low-Pass filter circuit Present in front of the ADC Channels.

Problems with SPI1-DMA:
   1. For every 1 Sec, we are communicating to this controller with 64 bytes of Data from Master(LPC 1778 controller) with DMA. Even though Slave Selection is low before the starting of communication,we are getting FF's for all 64 Bytes.But for the next time communication is success.

    For this, we configured SPI1 with following setting:
        1.SPI                    - Slave.
        2.Continuous     - Enable.
        3.CON[14:15]    - 00(Interrupt for transfer of every Byte)
        4.ZEN                  - Enable.
        5.CPOL                - 0.
        6.CPHA               - 1.
        7.DMA enabled for Both Tx and Rx of SPI1 but DMA interrupt is only Enabled for Rx.
        8.PCLK                - 2MHz.
        9.SCLK                - 500KHz (Also we have tried for 100KHz).

       Communication Packet Size    - 64 Bytes.

    Note: In firmware, we have used the Standard Driver files which are available in the home page of Analog Devices website.

       Please help us in resolving these problems.

Outcomes