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LM3S5749: JTAG programmer LM3S5B91

Part Number: LM3S5749
Other Parts Discussed in Thread: SEGGER

We have PCBs using LM3S5B91 that need firmware fixes. Since this part

is obsolete, please note the part number on the title is different.

The manual configuration setting in the JTAG LM flash programmer works to program the PCB

most times. Some times uploading flash contents to a file and erasing the flash is needed

to start programming the board. After programming the board few times, suddenly it says

unable to initialize the MCU. Giving hardware reset, power cycling the board, restarting the

computer makes no difference, seems like the MCU is locked up.

Is there anything else that can be done to program this MCU?

Thanks,

Priya

  • Hello,

    Our small tech group has found that (both) past "LM3S, LX4F" &  present TM4C" devices which "fail to program" may be "recovered" via:

    • Use of the vendor's "MCU Unlock/Recovery" mechanism.    (integrated w/in "LM Flash Programmer" - it is believed.)
    • Use of the Segger "J-Link" employing "SWD" (2-wire) rather than JTAG.   (Providing that the "Target MCU's SWD pins" may be directly (and uniquely) accessed!)    (i.e. any prior "board ICDI device" - connecting to the Target MCU -  has its "competing connections" removed!)

    Not a 100% guaranteed solution - yet has worked where "normal" vendor Unlock/Recovery methods have repeatedly failed.

  • Try the steps for "Recovering a Locked Microcontroller". You can use LM Flash Programmer or follow these steps from the datasheet.