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CC1125: CLKEN_CFM signal output

Josep Picanyol
Prodigy 30 points
Part Number: CC1125
Other Parts Discussed in Thread: MSP430F149

When employing the Custom Frequency Modulation mode, the CLKEN_CFM signal output to GPIO pin used as a trigger to read the CFM_RX_DATA_OUT samples (at 7200 Hz), has a pulse duration of only 50 nS (nanoseconds). In many cases this duration is to short to be recognized by the microprocessor as an interrupt. Is there a way to increase the pulse duration ?

  • 0
    TI__Guru**** 317180 points
    This is a signal that comes directly from the digital core and it's therefore not possible to extend. That said we have written code on a MSP430 using this signal and we have customers that uses this feature and I have never heard about an issue on this signal.
  • 0 in reply to TER
    Prodigy 30 points

    Thanks for the answer. But this signal is employed to generate an INT to a MSP430F149 uC. It works and no INT seems to be lost, but according to the MSP430 datasheet, a minimum of 1.5 times MCLK is necessary to be sure the INT is acknowledged. The uC MCLK works at 5 MHz (because power saving), so 300 nS minimum will be necessary.

  • 0 in reply to TER
    Prodigy 30 points
    Thanks for the answer. But this signal is employed to generate an INT to a MSP430F149 uC. It works and no INT seems to be lost, but according to the MSP430 datasheet, a minimum of 1.5 times MCLK is necessary to be sure the INT is acknowledged. The uC MCLK works at 5 MHz (because power saving), so 300 nS minimum will be necessary.
  • 0 in reply to Josep Picanyol
    TI__Guru**** 317180 points
    As said, this pulse is fixed. Meaning that you would need a different MCU to handle the signal. I look at at a random other MSP430 (www.ti.com/.../msp430f5438.pdf ) and it looks like the requirement for this is min 20 ns which is no issue.