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MSP430F5247 Reset problem

Pankaj Saraswat
Prodigy 20 points
Other Parts Discussed in Thread: MSP430F5247, MSP-FET

Hi,

We are using MSP430F5247 microcontroller in our project. When we touch its TEST/SBWTCK pin (SPY BI WIRE Interface), MCU resets. We have given wire on test point. Sometimes MCU resets even without touching this wire. This pin is internally pull down but we have tried another pull down too. Can you please help us to know root cause of this issue ?

  • 0
    TI__Mastermind 49692 points
    Hi Pankaj,

    I'm afraid that I don't fully understand your setup and how it's causing this issue. Are you using the MSP430F5247 on a custom board or target development board? What debugger are you using (e.g. MSP-FET)? Can you provide more background information about what is the "test point"? By "touching" the TEST/SBWTCK pin, are you referring to touching the pin with your finger or connecting the pin to VCC or GND with a jumper wire? I know you mentioned using an internal/external pull-down resistor, but it's unclear if VCC is being applied here.

    Also, do you have the watchdog timer disabled in your code? If not, it may be causing the reset. Please feel free to share your code, if possible.

    Regards,

    James
    MSP Customer Applications
  • 0 in reply to James Evans
    Prodigy 20 points
    Hi James,

    We are using MSP430F5247 on custom board and below is the link for debugger:
    http://www.ti.com/tool/msp-fet

    SBWTCK and SBWTDIO pins are terminated on smd test point where we solder wire and use for programming the MCU. MCU resets when we touch its tck wire unknowingly. Reset doesn't occur when we remove the programming wires.
  • 0 in reply to Pankaj Saraswat
    TI__Mastermind 49692 points

    Hi Pankaj,

    Pankaj Saraswat said:
    We are using MSP430F5247 on custom board and below is the link for debugger:
    http://www.ti.com/tool/msp-fet

    Thanks for providing this additional information.

    Pankaj Saraswat said:
    SBWTCK and SBWTDIO pins are terminated on smd test point where we solder wire and use for programming the MCU.

    This makes sense. Since you're using a custom board, I'd recommend reviewing MSP430 JTAG Design Pin-Outs Wiki page to make sure you're JTAG interface has the correct connections and other passive components to ensure proper connection. In Section 2.3.1 Note on Devices with TEST pins (taken from tidoc:slau320), it mentions that on some Spy-Bi-Wire capable MSP430 devices, TEST/SBWTCK is very sensitive to rising signal edges that can cause the test logic to enter a state where an entry sequence (either 2-wire or 4-wire) is not recognized correctly and JTAG access stays disabled. Unintentional edges on SBWTCK can occur when the JTAG connector is connected to the target device. Two workarounds are also discussed.

    Pankaj Saraswat said:
    MCU resets when we touch its tck wire unknowingly.

    What exactly touches the TCK wire? The connection to the MSP-FET, GND, VCC, or TDIO?

    Pankaj Saraswat said:
    Reset doesn't occur when we remove the programming wires.

    Good to know.

    Regards,

    James

    MSP Customer Applications

  • 0 in reply to James Evans
    TI__Mastermind 49692 points
    Hi Pankaj,

    I'm closing this thread, but please feel free to reply back if you have further questions about this topic. For unrelated questions, I'd recommend opening a new thread.

    Regards,

    James
    MSP Customer Applications
  • 0 in reply to James Evans
    Prodigy 70 points

    Hi James,

    We are facing the same issue as defined above.

    We are using MSP430F5247 in our custom board and using SBW interface to program the controller(MSP-FET). 

    Here i attached my schematic for your better understanding. 

    We directly connect two wires on TP16 and TP15 to program our MCU.

    The issue is that if we touch  TEST/SBWTCK with our hand our device gets rebooted and some time without touching this wire, same condition happened.

    Please help us to resolve this issue ASAP.

  • 0 in reply to Mohit Saharan
    TI__Mastermind 49692 points

    I'd recommend changing R146 to 47k Ohms and reduce C104 to 1.1 nF (since the upper limit for C104 is 2.2 nF and your board traces, wires, etc. could be exceeding this value as described in Note B here).

    Also, as discussed above, on some Spy-Bi-Wire capable MSP430 devices, TEST/SBWTCK is very sensitive to rising signal edges that can cause the test logic to enter a state where an entry sequence (either 2-wire or 4-wire) is not recognized correctly and JTAG access stays disabled. Unintentional edges on SBWTCK can occur when the JTAG connector is connected to the target device. As a workaround, try adding an external pull-down resistor (e.g. 4.7k Ohms) at the TEST/SBWTCK pin (as discussed here).

    Regards,

    James

    MSP Customer Applications

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