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I2C + SPI timing on Temperature Sensors

Matthew Hann
Expert 7185 points
Other Parts Discussed in Thread: AMC6821

Silicon temperature sensors consist of an on-chip diode-generated voltage, filtering, and an ADC.  Many times the initial problems that occur in communicating with temperature sensors has to do with improper timing of clock and data lines.  The easiest thing to do eliminate digital communication as a culprit for improper timing is to take a scope photo of the I2C or SPI event.  This makes it very easy to see if there are marginal clock edges and/or spurious noise that could be interpreted as an erroneous "start" or "stop" condition by the slave device. 

  • 0
    Prodigy 60 points

    Hi  Matt,

     

    Thnaks for you proactive support to TI user community.

    We have decided to use TI's thermal sensor AMC6821 in our system.

    I am able to write and  read the registers. I wrote the config register#4 with 0x88. Register address 0x04.

    But the both local and remote ststus regsiters are struck at default values.

    Do I have to do anything more to make it working?

    I mean any perticular procedure there to use this chip?

    Do you have any device driver source code for this chip?

    Looking forward to your support.

     

    Thanks and regards,

    Narasimha

  • 0 in reply to NARASIMHA BETINI
    TI__Expert 7185 points

    Narashima,

    It is difficult to speculate as to why you are unable to write to the registers and change their settings; however, an easy way to debug this problem would be for you to take scope shots of the register write events and post them to the forum .  This will help us eliminate faulty timing as a possible culprit to this problem.

    Matt

  • 0 in reply to Matthew Hann
    Prodigy 60 points

    Thanks Matt for the quick reply.
    I am able to write to the registers and read as well.

    Even after writing the config registers, the temperature status registers are struck with default temperatures.

    I wrote 0x88 to config register 4(address 0x04) and

    0x3c to config register 2(addr 0x01).

    And then started reading the local temperature status register at addr 0xa which still shows default value of 0x80.

    And the remote temperature register at addr 0xb too shows default value of 0x80.

    Please let me know asap.

     

    Regards,

    Narasimha

     

  • 0 in reply to NARASIMHA BETINI
    TI__Genius 9725 points

    Narasimha,

    I am the application support for AMC682x devices.  A quick look at your setup found that the bit 0 of Config register #1 (address 0x00) was not mentioned. To start the monitor at the default settings, this bit should be set to 1b. 

    Best regards,
    Wendy F.

     

  • 0 in reply to Wendy Fang
    Prodigy 60 points

    Thanks Wendy F.

     

    It works with config reg#1 bit 0 set to 1.

    Thanks a lot for your support.

    Narasimha