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STM32F37x SDADC data count offset change

Question asked by carpenter.greggory on Mar 25, 2013
Latest reply on Dec 3, 2014 by joee
I've been working with the SDADC hardware on the stm32f37x.  Using a sdadc clock of 6 MHz and software triggering 3 injected channels in single-ended zero-reference mode every millisecond.  I've noticed that when applying DC inputs to the three channels in question I see a periodic 'shift' in the counts output downward by around 10 counts and slowly drift back upward to the previous level on average, this shift appears to be temperature dependent as applying a heat gun to the PCB at a distance the frequency of the 'shift' behavior increases.  Has anyone else seen this behavior? Could this be a function of the underlying SDADC hardware implementation? When monitoring the inputs with an oscilloscope I do not see the shift which the SDADC is reporting. 

I welcome any ideas or comments and I'm including a screen-shot of the plotted data around the time of the 'shift' which occurs on counts reported for all channels.