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[ MSP430F6733IPN ] MSP-FET Unable to connect to target

Hidetaka
Expert 1080 points
Other Parts Discussed in Thread: MSP-FET, MSP430F6733

[ MSP430F6733IPN ] MSP-FET Unable to connect to target

 

We are facing communication problem between MSP-FET and target (MSP430F6733).

We have two boards, one is customer board, and the other one is MSP-TS430PZ100B MSP430F6736IPZ.

The issue is occurred only on customer board.

 

Case 1 : Customer board MSP430F6733IPN Vdd = 2.5V (MSP-FET Vcc-TARGET )

 

MSP-FET cannot connect to F6733 with SBW communication and error message

"Error connecting to the target:

Unknown device" show up.

Condition: C1 = 10nF ( This was for JTAG communication (not for SBW)).

 

CH1 : TEST/SBWTCK

CH2 : RSTn/SBWTDIO

CH3 : VDD = 2.5V(MSP-FET Vcc-TARGET )

 

Case 2: MSP-TS430PZ100B MSP430F6736IPZ Vdd = 3.3V (MSP-FET Vcc-TOOL)

 

For this case, the communication between MSP-FET and target successfully established.

Condition C1=2.2nF

 

CH1 : TEST/SBWTCK

CH2 : RSTn/SBWTDIO

CH3 : VDD= 3.3V(MSP-FET Vcc-TOOL )

 

Case 3 : Customer board MSP430F6733IPN Vdd = 2.5V (MSP-FET Vcc-TARGET ) with C1 = 1nF

 We know that C1=10nF (case 1) is not suitable for SBW communication, so changed this to smaller one 1nF.

But result is not stable yet, means some devices can communicate, but some others cannot.

See waveforms below for different customer boards.

//////////

N.G. Customer target board #4 with C1 = 1nF.

 

 ///////////

Good. Customer target board #5 with C1 = 1nF.

--

On top of that, we have checked their 2.5V power supply (LDO) on board during SBW communication,

so far no anomalies found.

 

Do you have any ideas of the root cause and work around of this behavior?

Regards,

Hidetaka.

  • 0
    TI__Guru**** 212077 points
    Hidetaka,

    Since the RST line is being pulled down too slowly such that it never reaches GND in the failing cases then there is something on the customer's board that is preventing the RST line from operating properly. Are there any components that could accidentally short the RST line or provide additional capacitance. Is the customer willing to provide their board schematic and layout? Can you explain in detail the differences between the two screenshots in Case 3?

    Regards,
    Ryan
  • 0 in reply to Ryan Brown1
    Expert 1080 points

    Ryan-san.

    Thank you for commenting.

    Then, I replaced C1 of two customer boards with 1nF by the addition.

    The two boards have observed the almost same waveform as the board of Case4.

    Also in communication of SBW, the two boards were OK.

    So, I replaced C1 of the board of Case3 once again, and also reworked soldering of the cable of SBW.

    As a result, I can obtain the waveform of Case4, and the same waveform and also OK SBW communication.

    Although the cause in the waveform of Case3 of not succeeding was unknown, it has improved on the same board.

    There was a request what becomes in 2.2nF about C1 from a customer after that.

    Moreover, SBW was OK even if it changed C1 into 2.2nF on another board.

    This waveform is as follows.

    From these results, what is necessary is C1=1~2.2nF.

    Regards,

    Hidetaka.

  • 0
    Prodigy 220 points

    On your eval board, the RST capacitor is DNP on the schematic (C3, 2.2nF) included in the "Hardware Design Files".  Are you sure it's there?  Maybe it was left out because it interferes with SBW.  You could try leaving the capacitor out completely.  Supposedly it is only needed if you have strong noise pickup.

  • 0 in reply to Till Rosenband
    Expert 1080 points
    Hello, Till-san.

    Thank you for the comment.

    The capacitor operated normally by 1nF or 2.2nF as I described previously.

    Regards,

    Hidetaka.

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