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Patriks
Senior
October 8, 2014
Question

SPC560D clock source

  • October 8, 2014
  • 1 reply
  • 553 views
Posted on October 08, 2014 at 15:56

Hello,

If I am using the command ''

asm volatile (''nop'');

'', how long should the controller need to execute this command?

I ask this question because I have tried to use it as an indicator for the system clock. Currently, I am using the SPC560D discovery board and my clock source is the FMPLL, configured for a clock of 48MHz. The SPC5-UDESTK and UDE Visual Platform shows me an execution time of 208ns for this command. This seems too much for me for a system clock of 48Mhz. Shouldn´t it be around 10ns?

To do another test, I used the internal 16Mhz RC as system clock. The strange thing is, that the execution time for this command is exactly the same.

Best regards,

Patrik

    This topic has been closed for replies.

    1 reply

    Erwan YVIN
    ST Employee
    November 14, 2014
    Posted on November 14, 2014 at 16:08

    Hello Patrik ,

    i am not sure that it could be a relevant information by using :

    SPC5-UDESTK is USB/JTAG token.

    to do this ..often , i prefer use a ETM. (not the same price)

       Best Regards

              Erwan