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FRDM-K22F 16bit single ADC, can't sample the >1.65V  voltage

Question asked by kent gu on Oct 28, 2015
Latest reply on Nov 1, 2015 by kent gu


I am a newer for kinetis chip.

Now I try " xx\freescale\KSDK_1.3.0\examples\frdm22f\driver_examples\adc16" example, I do like the below steps:

     #1, Remove the R23, and connect DC voltage source to J24.1 "ADC0_DP0"

     #2, Use "chnConfig.chIdx = (adc16_chn_t)kAdc16chn0" to select ADC channel


Now I can read the correct voltage when DC voltage source is < 1.65V, but for the voltage >1.65V, I can't correct the voltage. The questions is that the ADC input voltage is 0~3.3V because Vrefh is 3.3V? If yes, how I can read >1.65V voltage when ADC module work on 16bit ADC signal mode?