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MSP430FR5989: CPU clock speed in Debug mode

Guillaume Henri
Expert 4376 points

Part Number: MSP430FR5989

Hi,

The MSP430FR59xx family user’s guide specifies the following :

“8.2.3.7 Wait State in Debug Mode

When the device is in debug mode, no wait state is applied. The NWAITS[3:0] has no influence in debug

mod. In debug mode (for example, during JTAG access to FRAM), the device system clock is controlled

externally and can be stopped at any time, thus FRAM access needs to be completed without wait state

cycles. The running speed of the CPU and DMA never exceeds the maximum FRAM access speed limit in

debug mode.”

Consequently when the code is executed in debug mode (with JTAG pod plugged in) what is the CPU frequency? Is it 8MHz?

What is the CPU frequency when executing the code with JTAG in free running mode?

Thank you!

Best regards,

Guillaume

  • 0
    TI__Genius 17960 points
    Hi Guillaume,
    I'll will come back to you on this tomorrow.

    Best regards
    Peter
  • 0 in reply to Peter Spevak
    TI__Genius 17960 points
    Hi Guillaume,
    the explanation is pretty simple. Unfortunately the description in the UG is quite misleading. We will need to improve it.
    The statement on the debugging in this case does not mean debug mode from the user's point of view, where the understanding would be, having the setup connected through the debugger interface to the PC, while debugging the application, but the debug mode means here the real execution of debug activities through the JTAG or Spy-Bi-wire, e.g. accessing registers, accessing FRAM through the debug interface, stepping in single step mode, setting break point etc. In these cases, as soon as the JTAG/Spi-Bi-wire actively takes over control of the device, the CPU clock is switched to a clock generated in the debug interface, and the wait cycles are ignored.
    In the very moment, when code execution is resumed, the CPU operates with the selected clock source of the application, and thus the wait cycles are being applied according to the settings selected by the user.
    I hope this clarifies the situation.

    Best regards
    Peter

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