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snehal_p's avatar
snehal_p
Icon for Contributor rankContributor
3 years ago
Solved

Increase frequency of HPSGPIO

Hello, How can we increase the HPS gpio frequency? I'm driving Shift register CD4094 from HPS. Can I increase the frequency of clk generated from hps to drive cd4094? what is the maximum frequenc...
  • aikeu's avatar
    aikeu
    3 years ago

    Hi snehal_p,


    I try to check further regarding the gpio limitation on arm cortex a9 for the HPS.

    It shows that:

    "The PL061 PrimeCell General Purpose Input/Output (GPIO) is an AMBA compliant SoC peripheral that is developed, tested, and licensed by ARM Limited. Use the GPIO to generate or detect low frequency signals (less than 1MHz)."

    https://developer.arm.com/documentation/dui0440/b/programmer-s-reference/general-purpose-input-output--gpio

    It seems that the frequency you are capable of generating also meet around that range due to the limitation of the GPIO regardless of the instruction cycles which involves in the gpio toggling operation.


    Thanks.

    Regards,

    Aik Eu


aikeu's avatar
aikeu
Icon for Regular Contributor rankRegular Contributor
3 years ago

Hi snehal_p,


The signal behaviour is different from how I expected. It seems that each instruction cycle a lot slower than I thought.


Can share with me the oscilloscope actual results of the data and clock signal when sending the 8bit transter to the shift register?

Another thing to try is just by sending the clock signal example like below:

while(1)

(

alt_setbits_word( COMMON_TEXT_FOR_GPIO0, DISP_HMI_CLK );


alt_clrbits_word( COMMON_TEXT_FOR_GPIO0, DISP_HMI_CLK );

};

How the above gpio signal frequency clock will look like from the oscilloscope.


Thanks.

Regards,

Aik Eu


  • snehal_p's avatar
    snehal_p
    Icon for Contributor rankContributor
    3 years ago

    Hello Aik Eu,

    PFA oscilloscope images and code screenshot.

    AI_CLK_PIN in the code is continuous clock signal.

    Thanks,

    snehal_p