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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,


Are you trying to set the GPIO example from low -> high then high -> low continuously to function as a clock to the Shift register?

If that is the case the fastest time achievable will based on the instruction cycle of the HPS system. Meaning the time it takes for one single instruction to set a GPIO pin to high/low . You can only set the period of your generated clock slower than your system clock but not faster than that.


Thanks.

Regards,

Aik Eu


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

Hello Aik Eu,

Yes, system clock is 50 Mhz.

Thanks,

snehal_p