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MSP430F6734A: The Debug Interface to the device has been secured

Part Number: MSP430F6734A


A few days ago I was playing with the security options of MSP430F6734A in IAR.

I have added below pragma code in IAR, and Project Options->Debugger->FET Debugger->Download->"Allow erase/write access to BSL Flash Memory" and programmed the MSP properly.

After that program, I commented pragma code below and continue developing my application without any restriction. During that time I reprogram MSP430 maybe 10 times and never faced an issue.

#pragma location = 0x17FC
__root const uint8_t JTAG_password[] = {0x11, 0x22, 0x33, 0x44}; // -> 0x22114433

Today, I guess first time of power cycle of the device (power off and on), JTAG interface started giving following error:

"The Debug Interface to the device has been secured"

The part that we use MSP430F6734A, it has Device Descriptors in range 1A00h - 1AFFh that contain some ADC calibration parameters.

I don't want to erase BSL or Device Descriptors sections of the device.

I know the jtag password but still can't access. JTAG password editbox in IAR options is disabled, I don't know why.

I have tried MSP430Flasher like below but no chance:

MSP430Flasher.exe -w "USB_PRE.txt" -p 0x22114433 -v -g -z [VCC]

# Exit: 16

# ERROR: The Debug Interface to the device has been secured

How can I bring it back to unsecured position without losing BSL or Device Descriptor sections?


  • Device descriptor (TLV) with factory data is read only, and can't be changed.

    JTAG can be unlocked, by writing zeros to BSL area at fuse address by BSL.Than original BSL can be restored (FFh fuse values) by JTAG. Here is example with 5510...

  • I don't want to erase anything. I already know the 4 byte Jtag password hold at address 0x17FC for MSP430F6734A.
    Why does I still need to erase whole device?

    Issue here, MSP430Flasher -p 0x22114433 doesn't do its job.
  • I don't know how this is handle by IAR. For example, if you define JTAG password as 0x12345678, and than change it later (without POR) to 0x11223344. One way is that IAR erase BSL and write it back with new JTAG password. Other option is that IAR just overwrite old password with new one, without erasing BSL. You can read by BSL two words from 0x17FC to be sure about password contest.

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