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TMS320F28034: Questions about missing external crystal behavior

Johnny Chen
Expert 4980 points
Part Number: TMS320F28034
Other Parts Discussed in Thread: C2000WARE

Hi Champ,

I am reconfirming the missing external crystal behavior on F28034 for my customer. 

Since my customer is facing the clocking source - external crystal oscillator be interfered by high frequency, then DSP is died. In this condition, the JTAG cannot be connected, and it can only be fixed after re-power on.

(1). Referred to below thread, may I reconfirm the answer would be the same on F28034, correct ?

On missing clock condition, PLL is forcefully bypassed and OSCCLK source is switched to INTOSC1 (10MHz). After missing clock, we do need to reconfigure PLL in NMI interrupt, then 

continue running the application code.

https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1123812/tms320f280039c-clarify-missing-external-crystal-behaviors-by-default/4178411#4178411

(2). Besides, do we have any examples for that on F28034 ? I didn't see there is the one for F28034 in example.

(3). Is there any cautious on the hw design besides referring to Figure 8-8. Using the On-chip Crystal Oscillator ?

Thanks and regards,

Johnny

  • 0
    TI__Guru* 95315 points

    Johnny,

          Please refer to page 74 of www.ti.com/lit/SPRUI10. Case C or Case D explains what would happen if the XTAL oscillator fails due to noise. Note that we are making an assumption that only XTAL oscillator was impacted by the noise and that the rest of the chip is continuing to work fine. 

    Johnny Chen said:
    (2). Besides, do we have any examples for that on F28034 ? I didn't see there is the one for F28034 in example.

    There is no example in C2000ware specifically for missing clock handling.

    Johnny Chen said:
    (3). Is there any cautious on the hw design besides referring to Figure 8-8. Using the On-chip Crystal Oscillator ?

    Both the crystal and the load capacitors must be placed as close to the device pins as possible to reduce the loop area of the circuit. In addition to this, other usual precautions for robust EMC design applies.