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RTOS: How to use 20 adc sample channels with TM4C1294NCPDT chip?

nancy song
Intellectual 680 points
Other Parts Discussed in Thread: TM4C1294NCPDT

Tool/software: TI-RTOS

Hi all, 

  In my recent project, I need 20 adc sample channels with TM4C1294NCPDT chip.We know that there are four sample sequencers in TM4C ADC.And I have used sequencer0 for adc0 and sequencer1 for adc1 for my early project.I wonder the adc0 or adc1 can only be binded with one of the four sample sequencers.Does the adc0 or adc1 be binded with more than one sample sequencers?

  How could I use 20 adc sample channels in ADC_INT_SS0,ADC_INT_SS1 or so on?

 I have used  timer trigger for sequencer0 of adc0 and sequencer1 of adc1(12 channels in sum).But I just don't know how add more 8 channles.Could give me some suggestions about using adc 20 channnels with adc sequencer interrupt? 

  • 0
    TI__Guru*** 135355 points
    Hello Nancy,

    Reading Section 15.1 and Section 15.2 of the device datasheet, I don't believe there is a way to get a total of 20 samples via the sequencer.

    There are two ADC modules, ADC0 and ADC1, the datasheet states these modules operate independently and can execute different sample sequences. However, the maximum number of samples that a sample sequencer can handle is 8. This limits is the constraint that is going to limit you.

    I don't see any way to add 8 more channels via the sequencer. I don't think you can even add 4 more to get both ADC0 and ADC1 to use SS0 as from what I am reading, while independent you would need them to use the same FIFO in that case which is not possible. So it looks like the max is 12 which is using SS0 = 8 samples and SS1 = 4 samples as far as the sequencer goes. You would need to read out ADC0 results to clear the SS0 FIFO and get 8 more readings from ADC0 with SS0 after reading/clearing the SS0 FIFO to get up to 20 - not sure if that's feasible timing wise... though from a configuration standpoint, I see no reason the 2nd pass through with ADC0 can't be configured to hit the remaining 8 pins if you are using all 20 for sampling.