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MSP430F423A SD16 control register fault

Other Parts Discussed in Thread: MSP-TS430PM64

I'm trying to evalute the '423A SD16 using theMSP-FET430UIF debug interface and the MSP-TS430PM64 target board.  Everything on the chip works except a write to the SD16 control register SD16CTL at address 0x0100.  Writing a zero works.  Trying to write 0x0084 to the control register causes the debugger to float off into space and I frequently have to power cycle the UIF interface.

I've used mov.w and bis.w instructions using absolute, symbolic, indexed, or indirect addressing modes.  It fails in the same way using the IAR and CCS tools, using two different UIF debug modules, and using two different lot codes of '423A.  The only thing I haven't changed is the 64-pin target board, and I have one on order.

To recreate the problem all I have to do is fire up the chip with a reset routine that turns interrupts and the wdt off and then issue "mov.w  #0084h, &SD16CTL" and the debugger is dead.

Please, somebody tell me there's something stupid I don't know about.

Thanks, Mike Cushing


  • This has become more like a Keystone Cops movie than a chip evaluation - the fault has become worse.

    I did find that the fault occurs only when trying to turn Vref or Vmid on in the SD16CTL register, but it took 24 hours, because after executing the write several times, the debugger totally fails to download to chip, complaining "Error connecting to target: Unknown device."  Killing CCS5 and doing a full power cycle on the PC and the UIF multiple times didn't fix it.

    That happened yesterday.  This morning, it worked fine, failing to write to the control register but still working, about three times.  Then it stopped downloading again.

    At this point, I think this is just for your amusement.  The "Unknown device" failure occurs both with CCS5 running under Windows 7 and IAR5 running under XP.

    - Mike Cushing

  • RESOLVED:

    The only remaining component that I had not changed was the 64-pin target board (MSP-TS430PM64), which clearly can't effect the debugger, but...

    The replacement target board arrived today, I plugged the "Unknown device" '423A in, and it runs perfectly.  I suspect there's a pattern-sensitive JTAG problem on the original target board.

    Mike Cushing

  • Michael Cushing said:
    I suspect there's a pattern-sensitive JTAG problem on the original target board.

    It's possible that on the defective board, the trace between the connector and the MSP is broken. Or there is a bad solder point on the socket/MSP.
    High-frequency signals like the JTAG pulses may skip a small gap by capacitive coupling, but not reliably. So you're right, some patterns will go through fine, and some will be problematic. Temperature changes may further influence the severity of the distortion.

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