MSP430FR2111: 1.5-V on-chip reference power down fail

Hi Shang,

Please provide more details about your configuration when disable internal ref.

The following configuration：

void Init_ADC(void)
{
P1SEL0 = BIT0 + BIT1;
P1SEL1 = BIT0 + BIT1;

ADCCTL0 &= ~(ADCENC);
ADCCTL0 |= ADCON | ADCMSC | ADCSHT_2; // ADCON
ADCCTL1 |= ADCSHP | ADCSHS_2 | ADCCONSEQ_1|ADCSSEL_1; // repeat single channel; TB1.1 trig sample start
//ADCCTL2 |= ADCRES; // 10-bit conversion results
ADCMCTL0 |= ADCINCH_1 | ADCSREF_1; // A1 ADC input select; Vref=1.5V
ADCIE |= ADCIE0;

ADCCTL0 |= ADCENC; // ADC Enable
// ADC conversion trigger signal - TimerB0.1 (32ms ON-period)
TB0CCR0 = t1-1; // PWM Period
TB0CCR1 = t1-1; // TB1.1 ADC trigger
TB0CCTL1 = OUTMOD_3|CCIS_1; // TB1CCR0 toggle
TB0CTL = TBSSEL__ACLK | MC_1 | TBCLR; // ACLK, up mode
ADC_num=1;
}

Hi,

As you code your REF source is selected as VREF1.5, but you didn't turn on the internal REF module in PMM register. Selected the AVCC and AVSS for ADCSREFx bit in ADCCTL0 register.

Hi，

《MSP430FR4xx and MSP430FR2xx family User's Guide》21.2.4 Automatic Power Down describe：

When the variable on-chip reference is selected, the internal reference is always on if INTREFEN = 1. If
INTREFEN = 0, the reference is turned on only when an ADC conversion is triggered.

also 《MSP430FR58xx, MSP430FR59xx, and MSP430FR6xx Family User's Guide》34.2.4 Auto Power Down describe：

If REFON=1, the internal reference is on continually; otherwise, it is only requested when an ADC conversion is triggered.

   When i use MSP430FR5949，my REF source is selected as VREF(2.5V).The ADC sample resault correctly.the current consumption as low as 16uA.

but when i use MSP430FR2111, the same effect was not achieved.

FR5949 adc configuration：

void ADC_init(void)
{    
    P1SEL1 |= BIT1+BIT2+BIT4; //bat电池  DINT电流超大通道
    P1SEL0 |= BIT1+BIT2+BIT4;
        
    P2SEL1 |= BIT4; //取电电压C+
    P2SEL0 |= BIT4;
    
    P3SEL1 |= (BIT0+BIT1+BIT2);//电流通道2 电流通道1 电场采样
    P3SEL0 |= (BIT0+BIT1+BIT2);//+BIT3
    
    while(REFCTL0 & REFGENBUSY);
    REFCTL0 = REFVSEL_2;// | REFON;
    //while(REFCTL0 & REFGENRDY);//Reference voltage output is ready to be used
    
    ADC12CTL0 &= ~ADC12ENC;
    ADC12CTL0 |= ADC12ON|ADC12MSC; //          // Turn on ADC12, set sampling time
    ADC12CTL1 |= ADC12SHP|ADC12SHS_1| ADC12CONSEQ_1; //CSTARTADD_0++                // Use sampling timer, single sequence
    ADC12CTL2 |= ADC12RES_2|ADC12PWRMD;                 // 12-bit conversion results
    //ADC_ui();
   
    ADC12CTL3 &=~ ADC12TCMAP;
    ADC12CTL0 |=ADC12SHT0_1;
    ADC12MCTL0 = ADC12VRSEL_1+ADC12INCH_12;  //0001b = VR+ = VREF buffered, VR- = AVSS
    ADC12MCTL1 = ADC12VRSEL_1+ADC12INCH_14;
    ADC12MCTL2 = ADC12VRSEL_1+ADC12INCH_4+ADC12EOS;
    ADC12IER0 = 0x04;                              
    ADC12CTL0 |= ADC12ENC;
    
    TA0CCR0 = TIME_SAMPLE;//TIME_1MS;                         // PWM Period
    TA0CCR1 = TIME_SAMPLE;//TIME_1MS;                           // TACCR1 PWM Duty Cycle
    TA0CCTL1 = OUTMOD_3;//CCIE;// |                       // TACCR1 set/reset
    TA0CTL = TASSEL__ACLK | MC__UP;//|TAIE;           // ACLK, up mode     
}