Why is the recommended value for csHoldTime and csSetupTime 0x3?

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Why is the recommended value for csHoldTime and csSetupTime 0x3?

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Senior Contributor I

Hello,

the recommended value for csHoldTime and csSetupTime is 0x3.

pastedImage_1.png

Why is the recommended value for csHoldTime and csSetupTime 0x3? Is it okay to set it to 0x1 if my used flash device is fast enough or will the FlexSPI peripheral have problems with a value of 0x1?

Kind regards,

Stefan

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NXP TechSupport
NXP TechSupport

Hi Stefan Mitterhauser

    My own opinion is 0x03 value may meet a lot of the external flash csHoldTime and csSetupTime requirement.

   So, if your external flash also can use 0X03, you can use it, but if you still want to change the data, eg, 0X01, you can check your datasheet, if it meets your requirement, then try 0X01 to test it, I think it's Ok, it is not fixed to 0X03.

Wish it helps you!

Kerry

 

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NXP TechSupport
NXP TechSupport

Hi Stefan Mitterhauser,

   The csHoldTime and csSetupTime, you need to check your external flash datasheet, normally, it defines the related min time:

pastedImage_1.png

  So, when you configure the flexSPI configuration block, you need to use your flexSPI clock to calculate your CS setup time and the hold time, make sure the time is larger than your flash datasheet defined smallest time.

pastedImage_2.png

Wish it helps you!

Kerry

 

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Senior Contributor I

Hi Kerry,

thank you for your answer. I did take the values from the data sheet of our flash device, but it still would be good to know why NXP recommends a value of 3 in the reference manual - there must be a reason for that right?

Kind regards,

Stefan

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NXP TechSupport
NXP TechSupport

Hi Stefan Mitterhauser

    My own opinion is 0x03 value may meet a lot of the external flash csHoldTime and csSetupTime requirement.

   So, if your external flash also can use 0X03, you can use it, but if you still want to change the data, eg, 0X01, you can check your datasheet, if it meets your requirement, then try 0X01 to test it, I think it's Ok, it is not fixed to 0X03.

Wish it helps you!

Kerry

 

-------------------------------------------------------------------------------
Note:
- If this post answers your question, please click the "Mark Correct" button. Thank you!

 

- We are following threads for 7 weeks after the last post, later replies are ignored
Please open a new thread and refer to the closed one, if you have a related question at a later point in time.
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Senior Contributor I

Okay, thank you!

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