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MSP430FR6047: LFXT not working in the designed PCB

Prudhvi Sagar
Genius 3785 points
Part Number: MSP430FR6047
Other Parts Discussed in Thread: EVM430-FR6047

Hello,

I have made custom PCBs based on EVM430-FR6047 but LFXT is not getting detected by the MCU. It gets stuck at 

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do
{
CSCTL5 &= ~LFXTOFFG; // Clear LFXT fault flag
SFRIFG1 &= ~OFIFG;
}while (SFRIFG1 & OFIFG); // Test oscillator fault flag
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
.I have got the boards manufactured from multiple vendors and also used multiple crystals. This could be due to some issue on the power rails? Kindly help me out as we are facing a huge crisis now due to this issue.

Regards,

Prudhvi Sagar

  • 0
    TI__Expert 7080 points

    Hi 

    Sometimes the crystal don't work due to PCB layout. You could check your PCB design first follow this note：

    www.ti.com/.../slaa322d.pdf

  • 0 in reply to Allen Gao
    Genius 3785 points

    Hello Allen,
    Yes I had gone through this document earlier and am following the rules. Yet I am unable to make it work. Anything else that w=could be causing the issue?

    Regards,

    Prudhvi Sagar

  • 0 in reply to Prudhvi Sagar
    TI__Expert 7080 points

    Hi,

    Have you tried to increase or decrease the value of the coupling capacitors.  The value of the matching capacitor will also affect the crystal oscillation

  • 0 in reply to Allen Gao
    Genius 3785 points

    I have used capacitors few pf above and below the values designated value, still no response. Is impedance matching or something of that sort required here aswell?

    Regards,

    Prudhvi Sagar

  • 0 in reply to Prudhvi Sagar
    TI__Expert 7080 points

    Hi,

    The coupling capacitor will affect the crystal oscillation. Different brands of crystals may need its own value. Make sure the capacitor value meet your crystal spec.

    Another thing I want to know that is that multi device have the same problem?

    Have you try to cross check between your PCB and Launchpad with the same MUC and crystal to see the problem originate from the PCB or others?

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