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AMC7812: seeking support for I2C communication in AMC7812

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Replies: 16

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Part Number: AMC7812

        Hi, I am using a texas based I2C controller AMC7812 for reading ADC values of adc channels in AMC7812. The master controller is AT32UC3a1512 of atmel. I am able to send the I2C commands from master but I am not getting any ack or any data from AMC7812. Kindly suggest me how to get data from AMC7812. I2C mode is enabled by grounding SPI/I2C pin and the slave ID is also selected based upon A0,A1 and A2 pins. Seeking urgent support on this issue.

  • Hi Santosh,

    Can you share your schematic for the configuration? Are you sure the device is powered and configured correctly?

    Thanks,
    Paul
  • In reply to Paul_Frost:

    IOAS.zip

  • In reply to Paul_Frost:

    I had used the SDA and SCL connection for I2C ; A0, A1and A2 for slave selection and reset pin is given high.
  • In reply to santosh das53:

    Hi Santosh,

    I have a few questions:
    1. Have you confirmed that all the power supply pins are biased correctly? If one of the devices is powered down (IOVDD is 0V), then it could be holding the bus low.
    2. I do not see the source of AVCC on the schematic - can you confirm that it is 5V?
    3. Do you have pull-ups on the I2S lines?
    4. Can you share an oscilloscope capture of the digital communication?

    Thanks,
    Paul
  • In reply to Paul_Frost:

     Hi Paul,

    Thanks for the support.

    1. The power supply to ADDD, DVDD and IOVDD is 3.3 V and AVCC1 and AVCC2 is shorted to each other with no external power supply.

    2. Yes pull up to I2C is there to 3.3V through 1K resistor.

    3. Kindly find the required attachment for the wave form. Here I am sending slave id: 0xC2 and resistor address: 0x50 twice and was expecting acknowledgement on SDA. 

  • In reply to santosh das53:

    Hi Santosh,

    This timing looks okay - are you adhering to the required command format for a read?

  • In reply to Paul_Frost:

    Hi Santosh,

    Any updates?
  • In reply to Paul_Frost:

    Hi Santosh,

    If you where not able to solve this issue please feel free to respond to this thread, or if the thread is locked, then please create a new thread. I will go ahead and close this issue for now.

    Thanks,
    Paul
  • In reply to Paul_Frost:

    Hi Paul,
    Sorry for the delay, I had switched to the SPI because I am using AT32UC3a Atmel based controller and there was having some problem in the I2C driver. Now in SPI mode, I am getting all default values of ADC channels also I am able to set the AMC configuration register 0 for ADC internal ADC-REF-INT for getting internal reference to ADC, I can able to read the Read/Write, Address = 4Ch. the value I got is 0x24 for AMC configuration Read/Write, Address = 4Ch. But I am not getting any internal reference value at ADC-REF-OUT. ADC-REF-OUT is giving 0V only. Can you suggest any solution why ADC-REF-INT value is not reflecting at ADC-REF-OUT pin(Pin no 57)????

    Because of no ADC reference value I am not able to get ADC values from any of the ADC channels. Also I had tried by applying external ADC-REF to the ADC-REF-IN, then also I am unable to get ADC channel values.....

  • In reply to santosh das53:

    Hi Santosh,

    You also need to enable the ADC reference buffer and ADC itself in the POWER-DOWN REGISTER (Address 0x6B). Bits 14 enables the ADC, bit 13 enables the reference buffer.

    Set those bits to enable the ADC functions.

    Thanks,
    Paul

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