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ADC module results for MCF52259

Question asked by Eugenia Suarez on Oct 26, 2018
Latest reply on Oct 30, 2018 by Eugenia Suarez

I'm testing and analyzing an old project that was built within codewarrior for 7.2 arch and uTasker1.3. So I'm using uTasker ADC libraries. Viewing the adc results and de micro datasheets I have some unclear adc behaviour. I write hoping someone here could bring me some light if I missunderstanding something. The code has a single ended adc bit configured (ADC_0), loop mode and seq mode. Maybe is an uTasker issue. But I would like to have somethings about the MCU's adc cleared.

  • Reading the datasheet I see that VRefH max could be typically 3.3v. If adc resolution is 12b, I will have 4092 points. This means the maxim value that I can read in result registers is 4092, being equivalent to maximum voltatge input = 3.3V. Isn't it?
  • Is there any way to get more than 4092 value? I'm reading 21045, for example, so far from 4092!. 
  • Another question I have regarding the ADC block is if it is possible to have much more than 3.3 V to be converted? 5v, 10v, ... ,12v? Since I have understood, Vi converted rank depends on adc VREF max (3.3). But maybe I'm wrong. Could someone validate this?


Thanks in advance.