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problem in jtag connectivity

amrr hema
Prodigy 30 points
Other Parts Discussed in Thread: LM3S811, LM3S608

Hi All,


i am using lm3s811 ARM cortex m3 and i have problem in jtag connection

the problem is that CCS V5.5 told me that "error connecting to the target"

i have searched alot for this problem and no solution work well with me

i used LM flash also

i use simple code

int main(void) {

return 0;

}

when i use digital oscilloscope , there are data in Tclk ,Tdin and TMS but no data appears in TDO so processor can't see the Jtag 

i checked also the main oscillator

anyone could help me please

thanks in advance

  • 0
    Guru 47900 points

    You report use of LM3S811 yet schematic reveals LM3S608!   Might that confuse your helpers?

    Your "test code" is far shorter and substantially less comforting than code which blinks an Led/responds to a gpio input.  You may wish to force your code to remain w/in main(), as well.

    Some report of your board's history would be useful - did it ever work?  If the latter is true - might your last (inevitably SW change/improvement) have caused/contributed to your present plight?

    Usual suspect is your deliberate or unintentioned, "Repurpose of PC0-PC3" from their JTAG default.  And - should that be the case - "Houston - we/ve got a problem!"  (that line - not much older than your MCU)

    Your MCU (be it 811 or 608 {or any LM3Sxxx} was classed Sandstorm - and those early parts did not provide easy recovery from, "lost JTAG!"   (now he tells me!)  Note that "Sandstorm" is not an option w/in Utility/Recovery...

    If you provide more detail - others or I may be able to describe a, "not quite ready for prime time" recovery "struggle."

    Or - you can toss that board - acquire Launchpad - and wreck JTAG to your heart's content - as those parts are recoverable...

  • 0 in reply to cb1
    Prodigy 30 points

    the two mcu the same but i use lm3s811

    my code worked well with other processors like tive and lm3s9d92 but in lm3s811 no

  • 0 in reply to amrr hema
    Guru 117855 points

    amrr hema said:
    the two mcu the same

    If you say so!  Reality may intrude - suggest that 811 has larger Flash, SRAM and there may be some pinout/peripheral variations.  These early devices set records for number of power (Vdd, Vss) pins per device - have you insured that each/every such pin was well routed and that adequate (i.e. many), "bypass caps" are emplaced?

    "Code worked well w/other MCUs" does not (at all) answer, "Did this particular 811 board ever work?" 

    Your "test code" (past presented) is minimal in the extreme.  How would you know that it failed w/811?

    Unless you have large 811 stock it may make more sense to switch to the newer MCUs and boards!   All the gremlins (possible/likely) - as listed above - have been resolved - and the required detail/focus/effort demanded by board trouble-shooting is avoided...

    "Housebreaking a dead/dying Dinosaur" may not best serve your long-term, tech interests...

  • 0 in reply to cb1_mobile
    Prodigy 30 points

    i am using lm3s811 and set all its  requirement (error in schematic but actually lm3s811 was used)

    my code work well in lm3s811 previously but suddenly this error appeared to me in another word my circuit work well and suddenly didn't work

    i tried alot of codes and no one can work , i see that the problem that mcu can't see the jtag because there  is no Tdo