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MCU dead due to bad code?

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  • flare_theculture
    Hi everybody! I have some trouble with the OKI 675001: I m using this part now for about 3 month, debugging and programming an extern Flash (AM29LV320) via
    Message 1 of 3 , May 22, 2006
      Hi everybody!
      I have some trouble with the OKI 675001: I'm using this part now for
      about 3 month, debugging and programming an extern Flash (AM29LV320)
      via JTAG. Never had any problems. Now after changing the code and
      burning it as usual into the FlashROM the MCU is no longer responding
      to JTAG. Furthermore no activity on the MCU bus. OK, i thought that
      some ESD distroyed the MPU and took a new part. But the same happend
      again :(.
      Here the proceeding in detail:
      - via JTAG initialization- and flash program loaded into internal RAM
      - initialization of SDRAM with that code -> breakpoint
      - via JTAG flash data loaded into SDRAM
      - flash program started -> breakpoint
      - everything still works
      - hardware reset -> MCU dead
      (I'm using the Amontec Chameleon with the "Raven 8MHz witout Reset"
      configuration.)

      How can code destroy/disable the MCU? Can i somehow resurrect it?
      Any help appreciated, Tom
    • kendwyer
      Hi Tom, Your Flash code must be doing something to cause this..... After Flashing the part, disconnect the JTAG and then power on reset, does this help? When
      Message 2 of 3 , May 23, 2006
        Hi Tom,

        Your Flash code must be doing something to cause this.....
        After Flashing the part, disconnect the JTAG and then power on reset,
        does this help?
        When you connect JTAG after Flash boot, where is the PC pointing too?
        What is the value of the ROMAC and BWC resigters?

        Ken



        --- In OKI-ARM-mcus@yahoogroups.com, "flare_theculture" <th@...> wrote:
        >
        > Hi everybody!
        > I have some trouble with the OKI 675001: I'm using this part now for
        > about 3 month, debugging and programming an extern Flash (AM29LV320)
        > via JTAG. Never had any problems. Now after changing the code and
        > burning it as usual into the FlashROM the MCU is no longer responding
        > to JTAG. Furthermore no activity on the MCU bus. OK, i thought that
        > some ESD distroyed the MPU and took a new part. But the same happend
        > again :(.
        > Here the proceeding in detail:
        > - via JTAG initialization- and flash program loaded into internal RAM
        > - initialization of SDRAM with that code -> breakpoint
        > - via JTAG flash data loaded into SDRAM
        > - flash program started -> breakpoint
        > - everything still works
        > - hardware reset -> MCU dead
        > (I'm using the Amontec Chameleon with the "Raven 8MHz witout Reset"
        > configuration.)
        >
        > How can code destroy/disable the MCU? Can i somehow resurrect it?
        > Any help appreciated, Tom
        >
      • flaretom
        Hi! The problem is solved! In my code the RMPCON register is set to 9 switching the DRAM bank to zero address. But at this point the SDRAM controller isn t
        Message 3 of 3 , May 31, 2006
          Hi!

          The problem is solved!
          In my code the RMPCON register is set to 9 switching the DRAM bank to
          zero address. But at this point the SDRAM controller isn't initialized
          yet. This seams to disturb the MCU and even the JTAG interface gets
          locked.
          By activating the internal BootROM (BSEL1=0) the malicious code is
          disabled and it's possible to connect via JTAG.
          I tried that approach before, but somewho it didnt't worked. I can
          only guess that the connection of BSEL1 to GND was not right.
          OKI Germany was very helpfully and actually they found the solution.
          After checking the BSEL1 setting i was able to reactivate all my
          "toasted" boards :)).

          Thanks to all who tried to help!

          --- In OKI-ARM-mcus@yahoogroups.com, "kendwyer" <kendwyer@...> wrote:
          >
          > Hi Tom,
          >
          > Your Flash code must be doing something to cause this.....
          > After Flashing the part, disconnect the JTAG and then power on reset,
          > does this help?
          > When you connect JTAG after Flash boot, where is the PC pointing too?
          > What is the value of the ROMAC and BWC resigters?
          >
          > Ken
          >
          >
          >
          > --- In OKI-ARM-mcus@yahoogroups.com, "flare_theculture" <th@> wrote:
          > >
          > > Hi everybody!
          > > I have some trouble with the OKI 675001: I'm using this part now for
          > > about 3 month, debugging and programming an extern Flash (AM29LV320)
          > > via JTAG. Never had any problems. Now after changing the code and
          > > burning it as usual into the FlashROM the MCU is no longer responding
          > > to JTAG. Furthermore no activity on the MCU bus. OK, i thought that
          > > some ESD distroyed the MPU and took a new part. But the same happend
          > > again :(.
          > > Here the proceeding in detail:
          > > - via JTAG initialization- and flash program loaded into internal RAM
          > > - initialization of SDRAM with that code -> breakpoint
          > > - via JTAG flash data loaded into SDRAM
          > > - flash program started -> breakpoint
          > > - everything still works
          > > - hardware reset -> MCU dead
          > > (I'm using the Amontec Chameleon with the "Raven 8MHz witout Reset"
          > > configuration.)
          > >
          > > How can code destroy/disable the MCU? Can i somehow resurrect it?
          > > Any help appreciated, Tom
          > >
          >
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