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nRST problem on TMS570

Possessed
Intellectual 680 points
Other Parts Discussed in Thread: TMS570LS20216

Hi  guys

There is a problem with my TMS570LS20216.  The nRST pin is always showing logic 0.  I have compared my schematics with the one of TMS570 USB kit and they are the same, i. e., the pin is connected to pull up resistor and the resistor connects to the 3.3v and the pin also connects to a capacitor which connects to the ground. At first, i thought my chip might be broken, but the result is the same after i soldered a new one with a new board. The nRST pin is only connected to this simple circuit, no other elements are involved. I dont have any idea, what i might do wrong.

Could anyone tell me what might be the reason for this??

Thank you in advance

Rui

  • 0
    TI__Guru**** 198766 points

    It looks to me that your MCU itself is causing a system reset. Please double check your schematics, and probe the power rails, PORRST etc on your boards:

    1. PORRST: The nRST is driven low as an output whenever the nPORRST is driven low externally.

    2. The threshold set for your supervisor (if used): If the power supply (3.3V, or 1.2V) is below the threshold, the supervisor will generate the RESET to MCU

    3. Power rails (1.2V): if it is out of the valid range, the internal voltage monitor will generate a PORRST reset which also drive nRESET low.

    It would be helpful if you post your schematics here. 

    Regards,QJ

  • 0 in reply to QJ Wang
    Intellectual 680 points

    Thank you very much OJ Wang. The problem is solved after add a pull up resistor to nPORRST pin. However, the way to connect nPORRST in the TMS570 USB kit schematics always drives the nPORRST pin low. Perhaps you can modify it in future.

    Rui

  • 0 in reply to Possessed
    Prodigy 200 points

    Hello,

    I have the same NRST problem in TMS570. It is always low and PORRST pin is high always.

    because of low NRST, i am not able to flash also.

    kindly help me.

    regards&thanks,

    Padmrish