I am trying to utilize the internal 1.5V reference as my ADC voltage reference. First, I enable the reference by setting:
PMMCTL2 = REFBGEN+REFGEN+INTREFEN;
Then I wait for the REFBGRDY and REFGENRDY to go high, which they do.
For the ADC settings, I am selecting ADCSREFx = 001b in ADCMCTL0 (utilize VREF as Vr+)
Now, when I measure a 1.0V input, I am getting all 0x3ff (all 1's) for my conversion result, which is incorrect.
I have been able to successfully measure the 1.0V input using ADCSREFx = 000b (utilize AVCC as Vr+), so I am confident that my ADC settings are correct.
As an experiment, I set ADCSREFx = 000b and then measured Channel 13, which should return the measurement of the 1.5V reference, but I got all zeros.
So it appears my 1.5V reference is not generating the voltage. How can I enable it?