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MSP430G2553: Programming with MSP-FET over existing 14 foot cable using Spy-Bi-Wire

Robert Harmon
Prodigy 40 points
Part Number: MSP430G2553
Other Parts Discussed in Thread: MSP-FET

I have inherited a situation where somebody has installed an MSP430G2553 at the end of a 14 foot cable. Using Spy-Bi-Wire, it was intended that a person could program new firmware into the micro using the MSP-FET tool. I informed the persons involved that TI mentions no more than 8 inches for cable length. These are programmed using batch files that call MSPFlasher. It works fine using a short cable. I added the "-j slow"   parameter but it did not help. Is this a lost cause?  Thank you.

  • 0
    TI__Expert 5490 points
    Hello Robert,

    Just want to make sure I understand your setup.
    1. You have a PC with MSPFlasher connected to a MSP-FET tool which connected to MSP430G2553 and try to program it using Spy-Bi-Wire right?
    2. The 14 foot cable is the cable between your PC to MSP-FET tool or between the MSP-FET tool to MSP430G2553?
    3. When you use shorter cable it works fine and when you switch to 14 foot cable it does not work right?
    4. What you mean by it does not work? What is the error message from MSPFlasher?

    Thanks,
    Yiding
  • 0 in reply to Yiding Luo
    Prodigy 40 points
    Hi Yiding - thanks for responding.
    1. Correct
    2. The 14 foot cable is from the MSP-FET to the target MSP430G2553
    3. Correct
    4. Setting VCC to 3000 mv...done
    Accessing device...
    Exit: 16
    ERROR: Unknown device
    Disconnecting from device...done

    Driver : closed (internal error)
  • 0 in reply to Robert Harmon
    TI__Expert 5490 points
    Hello Robert,

    I believe the issue is caused by the long cable since the cable is adding a big capacitance to the RST line.
    In this article, see the firts figure. Note B says the upper limit is 2.2nF for the capacitor to use.
    processors.wiki.ti.com/.../JTAG_(MSP430)

    The RST line signal is a bi-direction signal and if your spy-bi-wire interface RST line has a large capacitance that crosses the limit then it will affect the timing of the signal so you will not be able to program the device.

    I recommend to shorten the cable length for your application.

    Thanks,
    Yiding
  • 0 in reply to Yiding Luo
    Prodigy 40 points
    Having tried the " -j slow " parameter for calling the MSPFLASHER utility, is there a way to slow the MSP-FET even slower? Would some kind of bidirectional buffer help? Thanks again.
  • 0
    Expert 2740 points

    Is this a lost cause?

    Yes. The cost of high speed interface is too high.

    A different device with serial boot loader may work.

  • 0 in reply to Robert Harmon
    TI__Expert 5490 points
    Hello Robert,

    You can try to remove the capacitor on the RST pin to lower the overall RST pin capacitance but I think the 14ft cable is still way too long for SBW. Since SBW is a hig-frequency serial protocol, the connection must be short and must not catch up crosstalk. While the 4-wire JTAG can easily span several meters of wire (We had a 5m flat cable in one project and no problems), SBW is much more sensitive to the cable length.

    Thanks,
    Yiding
  • 0 in reply to Yiding Luo
    Prodigy 40 points

    Thanks all for your responses.

    I appreciate it.

    Bob

  • 0 in reply to Yiding Luo
    Guru 34483 points

    Yiding Luo said:
    Since SBW is a hig-frequency serial protocol, the connection must be short and must not catch up crosstalk. While the 4-wire JTAG can easily span several meters of wire (We had a 5m flat cable in one project and no problems), SBW is much more sensitive to the cable length.

    AFAIK, this are the max frequency rates on interface lines for MSP-FET (TI DLL):

    4-wire JTAG 2-wire Spy-Bi-Wire
    slow 1 MHz 200 kHz
    medium 4 MHz 400 kHz
    fast 8 MHz 600 kHz

    Don't know how is 200kHz related to high-frequency, and 1 MHz is not. I don't see any reason why SBW should have any problems on such low rates, without cap on target device RESET pin, on longer (proper isolated) cable.

    EDIT: Don't know to what this SBW 200 kHz is related, because min Fftg for 2xx flash devices is 257 kHz.

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