• State Resolved
  • Locked Locked
  • Replies 11 replies
  • Subscribers 99 subscribers
  • Views 1311 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

C6713 DSK

michele marra
Prodigy 70 points
Other Parts Discussed in Thread: TMS320C6713B
Hi to all,
I'm new in this forum and I don't speak English very well, so I apologize for any errors.
Just a few  weeks ago I bought a TMS320C6713 DSK and now  I'm reading the Rulph Chassaing's book 
but it does not explain in depth the hardware on the DSK, so  I took a look at 
the "TMS320C6713 DSK Technical Reference" ( http://c6000.spectrumdigital.com/dsk6713/V1/docs/dsk6713_TechRef.pdf)
but while the DIP switches behave as I expect the LEDs seem to behave in the opposite way:

From the "TMS320C6713 DSK Technical Reference" (page 2-3): 
The 4 CPLD memory-mapped registers allows users to control CPLD functions in software. 
On the 6713 DSK the registers are primarily used to access the LEDs and DIP switches and control the daughter card interface...
USER_LED3 R/W User-defined LED 3 Control (0 = Off, 1 = On)
USER_LED2 R/W User-defined LED 2 Control (0 = Off, 1 = On)
USER_LED1 R/W User-defined LED 1 Control (0 = Off, 1 = On)
USER_LED0 R/W User-defined LED 0 Control (0 = Off, 1 = On)

Now looking at the schematic on page A-3 of the "TMS320C6713 DSK Technical Reference" 
it seems that the LED should light up when the respective "User-defined LED Control" is 0 
and it should turn offt when the respective "User-defined LED Control" is 1 ,
because the anode is connected to the source through the resistance 
and the cathode  is connected with the "User-defined LED Control".
Where am I wrong?
  • 0
    Prodigy 70 points

    Hello, I want to post a picture showing how the CPLD is connected to the LEDs


  • 0 in reply to michele marra
    TI__Guru* 84110 points

    Michele,

    How does the LED light behave if you use the software as described in the documentation? Does it work as advertised?

    Regards,
    RandyP

  • 0 in reply to RandyP
    Prodigy 70 points

    Dear RandyP,

    thanks for you interest , perhaps because of the time zone my answer may seem too late, but I was waiting anxiously for someone would reply.

    Unfortunately if I use the software as described in the documentation it works as advertised, so I do not know where my reasoning is wrong.

    I studied the  BSL (board support library) code provided by " Spectrum digital" and effectively it sets to one the bit corresponding to the LED that should light,

    calling from the main only the function  DSK6713_LED_ ()  all LEDs remain off while the corresponding "User-defined LED Control" are set to zero.



  • 0 in reply to michele marra
    TI__Guru* 84110 points

    Michele,

    michele marra said:

    Unfortunately if I use the software as described in the documentation it works as advertised, so I do not know where my reasoning is wrong.

    This is not an unfortunate situation. If our documentation did not match how the board and software operated, then we would have a bug in our product. But when it does operate as documented, it is working correctly.

    There are more than one possible answers for why your reasoning is incorrect. I do not know the answer, but I am willing to talk you through figuring it out if you care to do so.

    What are all of the connections along the way from the software instruction to the LED?

    What voltages are required at any point to achieve a given LED condition?

    What voltages do you observe at each of those connection points?

    What can explain any apparent inversions at any point along the way?

    Regards,
    RandyP

  • 0 in reply to RandyP
    Prodigy 70 points

    RandyP,

    thanks for your time, ,now I can't answer the third question because I do not have a tester at home, but I'm going to buy one soon.

    RandyP said:
     

    What are all of the connections along the way from the software instruction to the LED?

    We can turn on ( off ) one of the the four LEDs on the DSK setting to 1 ( to 0) the respective bit of the USER_REG contained in the CPLD,

    this is achieved using the functions included in the previous post.

    RandyP said:

    What voltages are required at any point to achieve a given LED condition?

    To turn on the LED It is required a low logic state because this is connected to the cathode( look at  the schematic)

    RandyP said:

    What can explain any apparent inversions at any point along the way?

    I have no idea, I'd love to read on the schematic not USER_LED0, USER_LED1, USER_LED2, USER_LED3 but

    Regards,

    Michele Marra.

  • 0 in reply to michele marra
    TI__Guru* 84110 points

    Michele,

    michele marra said:

    I'd love to read on the schematic not USER_LED0, USER_LED1, USER_LED2, USER_LED3 but

    It appears you have reasoned one possible answer to your question. If the CPLD logic is available from the vendor's website and the datasheet for the CPLD, then you may be able to prove or disprove this theory. If you accept it as a theory.

    Since the logic does work as described, which means you the user can use the code and board to achieve your goals by clearly following that description, what is the most important result to come from this discussion? Is it to have someone point you to a documentation error or a schematic error or a device failure or a missing inversion bubble? Or is the more important thing to reason out why the board and logic and software would be implemented the way that they are?

    Do you like the way it works?
    Do you wish it worked differently?
    How would you change it if you could change it?
    Can you change it?

    Regards,
    RandyP

  • 0 in reply to RandyP
    Expert 2210 points

    The CPLD contains logic circuitry that makes the LEDs behave according to the documentation for the register.  You cannot determine what that logic is by looking only at the schematic diagram; you also have to look at the VHDL or Verilog source code used in programming the CPLD.  However, this is all unimportant, since the only thing you need the LEDs for is to turn them on and off using software, and you already know hoe to do that.  It is much more important to obtain TI's documents for the TMS320C6713B, including the internal peripheral devices (McASP, McBSP, EDMA, 2-level cache, EMIF, timers, etc.).  Also consider obtaining TI's 5-6K interface board and an A/D or D/A daughterboard, preferably both so that you can digitize analog signals, process them on the DSP, and convert the result back to analog.  (You can instead experiment using just the audio subsystem included on the DSK6713.  There are other DSK compatible cards available, including Bitec's Ethernet interface.

  • 0 in reply to Douglas Gwyn
    Prodigy 70 points

    Douglas Gwyn,

    thank you for you answer , it is what I wanted to know.

    I am a beginner, I studied digital signal processing and now I wanted to develop practical applications, so I bought the card. I would like to understand fully how the code will interface to the hardware, but I do not know VHDL and then I'll take your advice.


    Regards

    MIchele Marra.

  • 0 in reply to RandyP
    Prodigy 70 points

    RandyP said:

    Or is the more important thing to reason out why the board and logic and software would be implemented the way that they are?

    You have hit the mark,

    the book I'm reading does not satisfy my desire to understand how the code interface hardware,  this is the first time I do something practical and my only theoretical knowledge of electronics represent a serious obstacle.

    Regards,

    Michele Marra.


  • 0 in reply to Douglas Gwyn
    Prodigy 70 points

    Hello Douglas,

    I gave a quick look at the VHDL code and found this: USER_LED( 3 downto 0 ) <= not CpldReg0(3 downto 0 ).

    Regarding the TI's 5-6K, are you sure that I can connect it to the TMS320C6713 DSK?

  • 0 in reply to michele marra
    Expert 2210 points

    The "not" in the VHDL code explains why the signal is inverted from what you had assumed.

    The 5-6K interface board definitely works with the DSK6713, and provides the connectors to which you can attach your choice of several A/D and D/A evaluation modules, as well as the "DAP" preamplifiers for those EVMs.  Whether to use a unipolar or bipolar version of the DAP depends on the particular EVM.  It often takes a while to get these parts so order them ASAP.