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MSP-FET will not blow fuse using SBW

Ryan Walmsley
Prodigy 170 points
Other Parts Discussed in Thread: MSP-FET, MSP430G2553

Hi,

I have since got the MSP-FET programming chips and am now trying to blow the JTAG fuse.

I first tried using the programming setup that I found worked fine and it would not blow. Here's the wiring for that

I then done some more Googling and found that for fuse blow support the TCK pin must be connected through a 330Ohm resistor and TEST (Pin 8) needed to be connected to the chip after the resistor. I found that the device allowed programming and debugging via the 330Ohm but after connecting Test I was prevented from doing any programming or debugging. In both cases the fuse blow did still not work either.

Here's the wiring for that.

I also tried putting a 47k Pull up resistor for reset with no change. Capacitors between VCC and Ground (100NF non polarised) and no difference at all. So any ideas on why it won't blow the fuse?

Thanks -

Ryan Walmsley

  • 0
    TI__Guru 56685 points

    Hell Ryan,

    Please see our HW User Guide (located here) for proper connections for your SBW connections, specifically Figure 2-2 will be of use to you. Please also note for proper SBW communication, the cap C1 in the figure cannot exceed 2.2nF.

    Regards,

    JH

  • 0 in reply to Jace H
    Prodigy 170 points

    So are you meant to add the capacitor? From what I could tell on many diagrams it said it was the maximum theoretical limit and should not be added and that it shouldn't be added unless required? But what is it required for?

  • 0 in reply to Ryan Walmsley
    Guru 227245 points

    “unless required” means, when you have a power supply that raises only slowly (few V/ms), the MSP could be released from brownout reset and start to run while the supply is still too low for operation (or even drops a bit again due to the rising load). This could crash the MSP and prevent it form starting. Adding a capacitor (and a pull-up) makes RST follow VCC with a delay, as long as VCC is still rising. This keeps the MSP in reset until VCC doesn’t rise anymore.
    If SBW isn’t used (but 4-wire JTAG), then 100nF and a 47k-100k pull-up are a good combo for almost every situation.

  • 0 in reply to Ryan Walmsley
    Prodigy 120 points

    Ryan,

    Have you been able to blow the JTAG Fuse using SBW? I have CCS 6.0.1, the MSP-FET and the MSP-TS430PW28A board and I can compile code on my msp430g2553 and I am trying to figure out how to blow the fuse. What code did you use to blow the fuse? I read on slau322 that the reference fonction for sbw blow is BlowFuse_sbw but cannot find it anywhere.

    Thanks in advance for the help.

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