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TMS320F280049: DAC Offset Adjustment

Wayne Huang
Genius 17115 points

Part Number: TMS320F280049
Other Parts Discussed in Thread: C2000WARE

Dear Champs,

I am asking this for our customer.

The user uses internal ref. 1.65V for the buffered DAC, and needs to calibrate offset to the spec like the datasheet for their application requirement.

In TRM,

15.2.2 DAC Offset Adjustment

it says "If the DAC is used at any reference voltage other than 2.5v, the offset trim must be adjusted to ensure the offset error performance stays within the device-specific data manual limits. The DAC offset register is a 16-bit register that contains the 8-bit signed offset trim in the lower half of the register. Use the function call DAC_tuneOffsetTrim() found in C2000Ware to adjust the offset."

Questions:

Would you please show us explicitly how the user set for DACTRIM for negative toward?

For example, they found the offset is 20mV when they set 0 as DAC value, how do they tune?

  • 0
    TI__Expert 7100 points
    Hi Wayne,
    Customer needs to use the function DAC_tuneOffsetTrim for trim.
    DAC_tuneOffsetTrim(uint32_t base, float32_t referenceVoltage);
    In this function, parameter base is the DAC module base address and parameter referenceVoltage is the reference voltage the DAC module is operating at.
    The referenceVoltage value should be a floating point number in the range specified in the device data manual.
    Note Use this function to adjust the DAC offset trim if operating at a reference voltage other than 2.5v. Since this function modifies the DAC offset trim register, it should only be called once after Device_cal(). If it is called multiple times after Device_cal(), the offset value scaled would be the wrong value.
     
    Regards,
    Hadi