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CCS/EK-TM4C123GXL: SPI Example code isn't working. Trying to interface with an AD9833

Christian Carter
Prodigy 10 points
Part Number: EK-TM4C123GXL

Tool/software: Code Composer Studio

I've been using this microcontroller for some time now and none of my other code has been this troublesome. I'm trying to interface with an AD9833 and I used a modified version of the example SPI code--the modification was just commenting out the UART sections--and the chip isn't giving the expected output. I've used an oscilloscope and a logic analyzer to look at what is coming out of the chip and it's unintelligible. I'm not sure if it's a code problem at this point however but it would still be nice just to verify and eliminate a potential cause to find the real problem, if it happens to not be the code. 

  • 0
    TI__Guru**** 191026 points

    Hi Christian,

      Does the MCU produce the correct output on the SSI interface? What do you mean the output is unintelligible? Does it comply to the AD9833 timing requirement? I'm not familiar with the AD9833. You will need to read its datasheet and make sure both the master (the MCU) and slave (the AD9833) have agreed on the same baudrate, phase, polarity, char length and etc. The UART should have nothing to this even if you remove the code associated with it if this the question you are asking. 

  • 0
    Guru 117855 points

    Christian Carter said:
    I'm not sure if it's a code problem

    Kindly note that, 'No one here can verify the 'code problem' - as no code was presented.'     And there exist multiple SPI examples - so your helpers are 'helpless.'

    It is always useful to provide Scope and Logic Analyzer 'Captures' - some here may be able to, 'better process (even) that thought 'unintelligible.'

    Finally - your including the Slave's Data sheet (at least a link) reduces the demand upon helpers - that's wise - is it not?