• State Resolved
  • Locked Locked
  • Replies 22 replies
  • Subscribers 83 subscribers
  • Views 2125 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TMS320F28377D: do these components actually exist in the control card? ADCIN0=ADCINA0?

Javy ZHANG
Intellectual 525 points
Part Number: TMS320F28377D

it is bit of confusing what does 'DNP (do not populate)' really mean in the schematics of the control card.

Does this actually mean that these components have been populated already somewhere? So we do not need to populate them?

I am using 28377d experimenter kit. The problem is with the ADC conversion. Currently I am getting really distorted results with great noise. I think one of the reasons could because of the RC filters connected with the ADC inputs. From the schematics, it shows these filters including resistors and capacitors (R30-R55, C19-C42 etc.). However, they are labelled with DNP. It is actually confusing.

This also affects the ADC references via R42 and R43.

1) Do I actually need to populate these components labelled with 'DNP'? Do they actually exist in the control card or chip?

2) By the way, is this true: ADCIN0=ADC_A0 (ADCINA0), ADCIN1=ADC_ADC_A1 (ADCINA1), ADCIN2=ADC_A2 (ADCINA2) and so on? I am using MATLAB/Simulink to programme, ADCIN0,1,2,3 appear in the Simulink ADC block. I wonder if there are true.

Thanks everyone

  • 0
    Guru 192875 points

    Hi,

    JIANWEI ZHANG said:
    1) Do I actually need to populate these components labelled with 'DNP'? Do they actually exist in the control card or chip?

    RC values are not populated as it provides flexibility to the user to use the ADCs in Single-ended mode or differential mode. As per your explanation it seems you've configured ADC in Single ended mode. In this case, RC is required and you can go for 56R and 3n3 as in other controlCards.

    JIANWEI ZHANG said:
    2) By the way, is this true: ADCIN0=ADC_A0 (ADCINA0), ADCIN1=ADC_ADC_A1 (ADCINA1), ADCIN2=ADC_A2 (ADCINA2) and so on? I am using MATLAB/Simulink to programme, ADCIN0,1,2,3 appear in the Simulink ADC block. I wonder if there are true.

    Yes... depends on module again whether its ADCA or ADCB etc. is selected.

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Intellectual 525 points
    Thank you very much, Gautam.

    It is made clear now. I will test to see how it goes.

    Yes I am using single-end mode of ADC conversion.
  • 0 in reply to Javy ZHANG
    Guru 192875 points
    You're Welcome!

    Goodluck & Regards,
    Gautam
  • 0 in reply to Gautam Iyer
    Intellectual 525 points
    Hi Gautam,

    Do you have any idea about why ADC channels have same results while they are connected to different sources?

    I used software as the trigger source. SOC trigger numbers for ADCIN0, ADCIN1 and ADCIN2 are configured as SOC0, SOC1, and SOC2 respectively. They are working in single-ended mode. SOC acquisition window is 7.

    ADCIN0 is connected to a sinewave generated by the function generator, while ADCIN1 is connected to 3.0 V and ADCIN2 is connected to the GND.

    However, these channels have same ADC results with ADCIN0.

    I really appreciate your help if you can provide any hint on this.

    Cheers,
    Jianwei
  • 0 in reply to Javy ZHANG
    Guru 192875 points

    JIANWEI ZHANG said:
    However, these channels have same ADC results with ADCIN0.

    I'm not sure whether I observed the same while implementing this with Simulink:

  • 0 in reply to Gautam Iyer
    Intellectual 525 points
    Hi Gautam,

    Thanks.

    I tried this example already. It is simple and straightforward.

    Why the SOC trigger source was set to CPU_TINT0n? Should I connect the ADCIN0 to the PIN9, ADCIN1 to PIN11 and ADCIN2 to 15 and so on?

    Cheers,
    Javy
  • 0 in reply to Javy ZHANG
    Guru 192875 points

    JIANWEI ZHANG said:
    Why the SOC trigger source was set to CPU_TINT0n? Should I connect the ADCIN0 to the PIN9, ADCIN1 to PIN11 and ADCIN2 to 15 and so on?

    I prefer ADCs to be triggered by CPU timer or ePWM. So its just about the preference. 

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Intellectual 525 points
    Thanks Gautam.

    Why there are 24 channels (ADC_A0 - ADC_A5, ADC_B0 - ADC_B5, ADC_C0 - ADC_C5 and ADC_D0 - ADC_D5) while only 16 inputs are availabel (ADCIN0 - ADCIN15)? How do they correspond to each other? Are ADC_IN14, 15 different from others?

    I am still getting same results from ADCIN0 and ADCIN1 when they are connected to different sources. I have soldered filters onto the control card. Noise has been reduced slightly.

    Cheers,
    Javy
  • 0 in reply to Javy ZHANG
    Guru 192875 points

    JIANWEI ZHANG said:
    Why there are 24 channels (ADC_A0 - ADC_A5, ADC_B0 - ADC_B5, ADC_C0 - ADC_C5 and ADC_D0 - ADC_D5) while only 16 inputs are availabel (ADCIN0 - ADCIN15)? How do they correspond to each other? Are ADC_IN14, 15 different from others?

    I didn't get your question... F28377D has 12 Channels in 16-bit Differential mode and 24 Channels in 12-bit Single-ended mode. You can configure all of these in simulink.

  • 0 in reply to Gautam Iyer
    Intellectual 525 points

    In the adc schematics show below, it has 24 channels

    however in diagram below, it has only 16

     

    to make the questions simple, I want to know how to make the hardware connections with 28377d control card.

    e.g. in the single-ended mode, i want to use ADCIN0, 1, 2  (in simulink block). what pins connection should I make? is ADCIN0 connected with ADC_A0 and ADCIN1 is connected to ADC_A1?  is it like this?

    Thanks 

    Javy

  • 0 in reply to Javy ZHANG
    Guru 192875 points

    JIANWEI ZHANG said:
    e.g. in the single-ended mode, i want to use ADCIN0, 1, 2  (in simulink block). what pins connection should I make? is ADCIN0 connected with ADC_A0 and ADCIN1 is connected to ADC_A1?  is it like this?

    Ok, let me make it crystal clear. In Simulink you can select Module (A, B, C and D) and Conversion channel (ADCIN0, ADCIN1 etc). If you select Module A and Conversion channel ADCIN0: it means you've selected ADCINA0 or ADC-A0. Similarly for B, C and D modules.

    ADC Module Selection

     

    Conversion Channel Selection

     

    I hope its clear now.

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Intellectual 525 points

    Thanks again Gautam.

    do we only have 6 channels for each module with the experimenter kit? e.g. for module A, it has only ADC_A0 to ADC_A5. as shown in the photo below

    What about other channels i.e. ADCIN 6 to ADCIN 15 in Simulink block, are they useless? 

  • 0 in reply to Javy ZHANG
    Intellectual 525 points
    not only with the experimenter kit. for the MCU it also has only ADC_A0 to ADC_A5.

    It claims to have 16 single-ended mode channels and 8 differentail mode channels. How can we make 16 or 8 channels with only 6 ADCs (ADC_A0, 1, 2, 3, 4, 5) in each module?

    I am still trying to figure this out. any clues?
  • 0 in reply to Javy ZHANG
    Guru 192875 points

    JIANWEI ZHANG said:
    not only with the experimenter kit. for the MCU it also has only ADC_A0 to ADC_A5.

    It claims to have 16 single-ended mode channels and 8 differentail mode channels. How can we make 16 or 8 channels with only 6 ADCs (ADC_A0, 1, 2, 3, 4, 5) in each module?

    I am still trying to figure this out. any clues?

    Please go through the device datasheet for the pinouts of 176-Pin PTP package. It has A0-A5, B0-B5, C2-C5, D0-D5.

  • 0 in reply to Gautam Iyer
    Intellectual 525 points
    yes I knew these.

    but is says each module has 16 single ended channels. How to get 16 channels using A0-A5 in module A.
  • 0 in reply to Javy ZHANG
    Guru 192875 points

    JIANWEI ZHANG said:
    but is says each module has 16 single ended channels. How to get 16 channels using A0-A5 in module A.

    Where is this fact mentioned? Can you point out in any TI document?

  • 0 in reply to Gautam Iyer
    TI__Guru 57255 points

    Hi Jianwei,

    I would recommend looking at page 94 of the current F28377D datasheet (SPRS880G):
    http://www.ti.com/lit/gpn/tms320f28377d

    Notice that there are 24 analog inputs to the device (red triangular input ports), 4 ADC peripherals, and 16 analog input channels per ADC. 

    Also notice that ADCIN14 & ADCIN15 attach to all 4 ADC peripherals, and this is why it is named a bit different from the other ADC pins.

    Hopefully this helps.


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    Intellectual 525 points

    Thanks Brett. That makes sense.

    So although each module has 16 analog input channels, only 6 are available for ADC conversion and they are ADC_A0 to ADC_A5, right?

    In fact, these correspond to ADC_IN0 to 5 respectively in the Simulink ADC block. ADCIN_6 to 15 are redundant according to my best knowledges.

    Cheers,

    Jianwei

  • 0 in reply to Javy ZHANG
    TI__Guru 57255 points

    Hi Jianwei,

    JIANWEI ZHANG said:

    So although each module has 16 analog input channels, only 6 are available for ADC conversion and they are ADC_A0 to ADC_A5, right?




    Mostly.  Peripheral ADC-A can sample/convert up to 8 external signals.  ADCINA0 - ADCINA5 & ADCIN14 & ADCIN15 (ADC-A's CHSEL = 0-5, 14, 15).  
    ADC-A can additionally be used to read the internal temperature sensor.

    The Technical Reference Manual (TRM) can also be a helpful document, if you are not aware of it:
    http://www.ti.com/product/tms320f28377d

    [note that all ADC modules/peripherals may not be set up to convert the same amount of external signals.  The datasheet should be used to help comprehend this]


    Thank you,
    Brett

  • 0 in reply to Brett Larimore
    Intellectual 525 points
    Thanks Brett.

    Do you have any idea on this issue?
    ___________________________________________________________________________
    Do you have any idea about why ADC channels have same results while they are connected to different sources?

    I used software as the trigger source. SOC trigger numbers for ADCIN0, ADCIN1 and ADCIN2 are configured as SOC0, SOC1, and SOC2 respectively. They are working in single-ended mode. SOC acquisition window is 7.

    ADCIN0 is connected to a sinewave generated by the function generator, while ADCIN1 is connected to 3.0 V and ADCIN2 is connected to the GND.

    However, these channels have same ADC results with ADCIN0.
    _____________________________________________________________________________

    Jianwei
  • 0 in reply to Javy ZHANG
    TI__Guru 60865 points
    Hi Jianwei,

    If you are using Simulink you need to configure both the ADCCLK divider and the S+H duration to be quite a bit different than the defaults in Simulink. See: e2e.ti.com/.../573259
  • 0 in reply to Devin Cottier
    Intellectual 525 points
    Thanks Brett. I will try this and see how it goes.