[MPC5744] ADC Oversampling Software Test

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[MPC5744] ADC Oversampling Software Test

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ahmadessameldin
Contributor I

Dears, 

I am writing to ask about ADC safety mechanism described in the Safety Manual for MPC5744P as below: 

Unbenannt.JPG

With these invariants: number of samples needed, threshold of the difference between converted values that indicates a faulty acquisition. 

Can you please provide more details how to implement this mechanism? 

Thanks in advance, 

Best Regards

1 Reply

169 Views
petervlna
NXP Employee
NXP Employee

Hi,

I do not understand the questions as answer for it is already in you post.

Against a random fault, three consecutive analog values are converted for each acquisition to implement the ADC_SWTEST_OVERSAMPLING. The figure below shows the sampling of an analog signal at different points in time (A1, A2 and A3). Every conversion is indicated by an arrow, which indicates the converted digital value by its length. The second acquisition (A2) is faulty because the first converted value is quite different respect the other two.

So you have to acquire 3 samples.

Threshold is given by your application countermeasure requirements.

Peter