i.MXRT1050 reference voltage ADC measuring

[peterbutko]

HI,
I need to measure voltage VREFSL with ADC but in the reference manual are not described this option. Is there just VREFSH = internal channel, for ADC self-test, hard connected to VRH internally (ref. manual page number 508). So is possible use as input to the ADC reference voltage VREFSL (internally)? In capture 14.3.2 is written that The ADC can be configured to use reference pairs as the reference voltages used for conversions (VREFSH and VREFSL). Can I set ADC channel with VREFSL voltage?

Thank You. 

[Bio_TICFSL]

Hi Peter,

If both are between the minimum Ref Voltage High and VDDAD, yes you can. These voltage references are selected by configuring ADC_CFG

[peterbutko]

Hi,

thank You for your answer, but I have still a problem. When I set register ADCx_CFG[REFSEL] to Select VREFH/VREFL as a reference voltage (00) and input channel ADCx_HC[ADCH] to 11001 (VREFSH = internal channel, for ADC self-test, hard connected to VRH internally) then I can measure value logic high (VREFSH - reference voltage select high). How Can I set value logic low internally (VREFSL - reference voltage select low)?