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Question asked by Stefan Mitterhauser on Feb 5, 2020
Latest reply on Feb 7, 2020 by jeremyzhou



I have already posted some questions regarding ADC and ADC_ETC in this post but have got no answer so far. Now I have another question.

The RT1020 Reference Manual provides this diagram where I added some information for my question below.


I think the above timing diagram would equal to these settings in MCUXpresso Config Tools:



Question 1:

Are my following thoughts regarding the signals correct?

  • The xbar_trigger comes from the peripheral I chose (PIT_TRIGGER0)
  • The xbar_trigger will be internally delayed in the ADC_ETC peripheral and after the Initial delay it will generate an internal signal trigger_req.
  • Some other part of the peripheral will receive the trigger_req signal and send the adc_trigger signal to the ADC peripheral. Each pulse on the adc_trigger signal corresponds to one ADC_ETC chain entry for the selected trigger. Therefore after the initial delay the first trigger pulse will start the conversion of chain element #0, the second pulse will start conversion for chain element #1 and so on. Chain elements #3 and #4 will be triggered back2back.



Question 2:

Is it correct that Chain element #3 has b2b enabled which means "If chain #2 finished the conversion start conversion of chain #3 as soon as possible"?



Question 3:

Is it correct that the b2b field of Chain #0 has no effect because it is the first chain # which will be triggered and it only waits for the initial delay?



Question 4:

The Conversion control group can be selected for every chain element. The conversion control group specifies which control register for hardware triggers and which result register (ADCx_HCn & ADCx_Rn) will be used for the conversion.

If I set up my chain element #0 and chain element #4 to use the Conversion control group 0, will the conversion result of chain #4 overwrite the conversion result of chain #0?



Question 5:

Do I have to set up the Conversion control groups in the ADC peripheral driver with MCUXpresso Config Tools like this

(every Conversion control group with Channel number set to CHANNEL_DRIVEN_BY_ADC_ETC) or will it be enough to initialize the ADC_ETC and the ADC channels will be initialized by the ADC_ETC peripheral?

If I set up the channels like shown above it will result in the warning that there are some duplicated ADC channels in the configuration > the warning suggests that I am doing something wrong here.


Kind regards,