Notification of internally generated FB_TA?

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Notification of internally generated FB_TA?

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yorknh
Contributor IV

I am using the Flexbus on a k64 to communicate with an FPGA. I am using the FB_TA signal as the primary way to terminate transactions but I do have autoAcknowledge enabled and waitStates set to 63 as sort of a fallback mechanism in case the bus were to hang. My question is, is there a bit in a register somewhere or an interrupt that can be configured to inform me that a FB_TA signal was internally generated?

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kerryzhou
NXP TechSupport
NXP TechSupport

Hi Larry York ,

   About FB_TA signal interrupt or the register, I didn't find the specific status register.

   About the interrupt, I just find this description:

pastedImage_1.png

Another way, maybe you can connect FB_TA to another GPIO input pin which can support interrupt, then use the GPIO interrupt to detect it.

Wish it helps you!.

If you still have question about it, please kindly let me know.

Kerry

 

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yorknh
Contributor IV

Hi Kerry, I had seen the part that you highlighted prior to asking the question. The problem is that FB_TA needs to be externally generated and it is working, but if there ever is a problem I wouldn't know it directly because the auto-acknowledge would happen without any indication.

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kerryzhou
NXP TechSupport
NXP TechSupport

Hi Larry York

   Thanks for your updated information.

    Do you mean, when the FB_TA is not generated, and auto-acknowleage happens, you don't know it and you try to know the auto acknowlege happens, right?

Kerry

 

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yorknh
Contributor IV

Yes

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kerryzhou
NXP TechSupport
NXP TechSupport

Hi Larry York

  Do you enable the CSCR[AA]=1?

  If yes, the related FB_TA should be generated internally after a specified number of wait statues.

  The auto-acknowleage may also have relationship with the FB_TA signal when you enable AA.    

  After enable the AA, do you test the FB_TA pin wave, I think when the internal signal is generated, the pin may also can find the change,  do you test it?

Kerry

 

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yorknh
Contributor IV

Hello Kerry,

You don't seem to be understanding the question. I know that AA works. I know that having the FB_TA driven by an external device works. I know if AA is enabled and the external device takes longer than 63 clocks to drive FB_TA that FB_TA will be internally generated. I want to know if that is happening.

Larry

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kerryzhou
NXP TechSupport
NXP TechSupport

hi Larry York,

  Sorry for my later reply, today, I help you to check with our expert who is familiar with flexbus.

  He told me, the flexBus IP really didn't have the detail register to identify the internal FB_TA(auto-acknowleage happens), but you can detect the FB_CS pin:

pastedImage_1.png

When the FB_CS is happens, you can use your wait states time, after the wait states time is finished, you can consider the FB_TA is generated. Maybe it is not very precise, but it should be enough to use it.

Wish it helps you!

If you still have questions about it, please kindly let me know.

Kerry

 

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