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PDB continuous mode, 2 ADCs in parallel, DMA linking & scatter/gather

Question asked by yannick jeantet on Dec 14, 2017
Latest reply on Dec 19, 2017 by Jorge Antonio Alcala Vazquez



I am learning to use a MK66FX1M0VMD18 (teensy 3.6).


My goal is to record datas from 8 analog inputs converted with the ADC0 and ADC1.


I read the "K66 Sub-Family Reference Manual".

Now I wonder if the following idea  is possible :


The  PDB  would be in continuous mode and its two channels 0/1 would trigger in parallel :

  -  ADC_0_A     which thanks to the back to back mecanic, would trigger ADC_0_B

  -  ADC_1_A               "                                      "                              "          ADC_1_B


At this point I would dispose of a set of four results in ( RA0 RB0 RA1 RB1) that I could  transfer with DMA,  in a circular buffer...


This  DMA transfere would be triggered , for exemple, by the end of conversion of ADC_1_B.

This DMA would it turn trigger through the "link" mecanism, another dma channel which would copy in the right registers of the ADCs (ADCx_SC1n),   the adresses (ADCH)  of four new data sources.    Lastly using " scatter/gather "  the TCD of this last DMA channel would be updated in order to toggle between analog inputs 1..4 and 5..8.


And so on . . .


Theoretically  it seems possible... but there are probably so many pitfalls to avoid, that I wish to get your advices and warning,  before diving in...


Sorry for my bad english.