S32K328 ADC channels

[mertsahin]

Hi,

Is it possible to read all 72 pins of ADC at the same time?

ADC0 has 8 precision, 16 standard

ADC1 and ADC2 also.

I wonder is it possible to read all 72 of them at the same time?

Thanks a lot.

[mertsahin]

Many thanks VaneB.

[VaneB]

Hi @mertsahin 

It is possible to measure all the ADC channels, but you must allow the capacitors of each ADC to discharge between measurements to avoid noise. Therefore, the more channels you use, the longer it will take to measure all the samples.

Please take into consideration the ADC specs provided in the data sheet.

B.R.

VaneB

[mertsahin]

If we can read them in parallel, why should we wait for longer time if we use more channels.

I presume the capacitors at each channel may discharge at the same time 

Is that correct?

[VaneB]

Hi @mertsahin 

I am sorry if I did not make myself clear.

Each ADC is a separate module, so you can take measurements from all three at the same time. What are not "independent" (so to speak) are the channels that each module has. They are all connected to the same hardware. For example, if you measure channel 0 of the ADC 0 you have to wait for the capacitors to discharge to measure channel 1 of ADC 0, but you can take measurements of channel 0 of ADC 0, ADC 1 and ADC 2 at the same time since the channel is not shared between each module.

[mertsahin]

Thanks for the explanation.

So each ADC channel has 8 precision, 16 standard.

This means for ex channel 0 of ADC0, ADC1 and ADC2, we can measure at the same time. 

If we would like to get all 72 channels at the same time. We need to wait longer. Right?

[VaneB · Accepted solution]

Hi @mertsahin 

You can only measure 3 channels at the same time and they have to be each from a different ADC. And to obtain all the channels of an ADC you have to finish the measurement of one channel to start the next one giving the necessary time between each measure.

[mertsahin]

To conclude the topic, 

if I need all the measurements from 72 channels in total, I need to wait 24 times a specified time. If I wait that amount of time, I will obtain all ADC results (all 72 channels) at the same time.

Let's say period for 3 simultaneous channel measurements from different ADC blocks it "t"

If I wait for 24*t, I will have all the results.

Is that correct? 

[VaneB]

Hi @mertsahin 

Theoretically, it would work like that.