TMS320F280025C: Driverlib Functions中的ADC校准函数ADC_setOffsetTrim错误

Chen_xd

Part Number: TMS320F280025C
Other Parts Discussed in Thread: C2000WARE

C2000Ware_5_00_00_00\driverlib\f28002x\driverlib\adc.c中的函数ADC_setOffsetTrim内容如下：

void
ADC_setOffsetTrim(uint32_t base)
{
    uint16_t *offset;
    uint32_t moduleShiftVal;
    uint16_t offsetShiftVal;
    uint16_t analogRefRegVal;
    ADC_ReferenceMode refMode;
    ADC_ReferenceVoltage refVoltage;

    //
    // Check the arguments.
    //
    ASSERT(ADC_isBaseValid(base));

    //
    // Assign a shift amount corresponding to which ADC module is being
    // configured.
    //
    switch(base)
    {
        case ADCA_BASE:
            moduleShiftVal = 0U;
            break;
        case ADCC_BASE:
            moduleShiftVal = 1U;
            break;
        default:
            //
            // Invalid base address!!
            //
            moduleShiftVal = 0U;
            break;
    }

    //
    // Read the Analog Reference Control Register value to determine the
    // ADC reference mode and reference voltage value.
    //
    analogRefRegVal = HWREGH(ANALOGSUBSYS_BASE + ASYSCTL_O_ANAREFCTL);

    //
    // Calculate refMode and refVoltage based on input ADC base
    //
    refMode = (ADC_ReferenceMode)((analogRefRegVal >> moduleShiftVal) & 1U);
    refVoltage = (ADC_ReferenceVoltage)((analogRefRegVal >>
                 (ADC_VOLTAGE_REF_REG_OFFSET + moduleShiftVal)) & 1U);

    //
    // Offset trim for internal VREF 3.3V is unique and stored in upper byte.
    //
    if((refMode == ADC_REFERENCE_INTERNAL) &&
       (refVoltage == ADC_REFERENCE_3_3V))
    {
        offsetShiftVal = 8U;
    }
    else
    {
        offsetShiftVal = 0U;
    }

    //
    // Set up pointer to offset trim in OTP.
    //
    offset = (uint16_t *)((uint32_t)ADC_OFFSET_TRIM_OTP + moduleShiftVal);

    //
    // Get offset trim from OTP and write it to the register.
    //
    EALLOW;
    HWREGH(base + ADC_O_OFFTRIM) = (*offset >> offsetShiftVal) & 0xFFU;
    EDIS;
}

当该函数用于校准ADCA时，可以正常校准。

但用于校准ADCC时，参数moduleShiftVal的值是1，注意第45-47行，此时赋给refMode和refVoltage的值分别是analogRefRegVal（寄存器ANAREFCTL）值的bit1和bit9。

而寄存器ANAREFCTL的位域图如下：