SLAA685 December   2015 CC430F6125 , CC430F6125 , CC430F6126 , CC430F6126 , CC430F6127 , CC430F6127 , CC430F6135 , CC430F6135 , CC430F6137 , CC430F6137 , CC430F6147 , CC430F6147 , MSP430AFE221 , MSP430AFE221 , MSP430AFE222 , MSP430AFE222 , MSP430AFE223 , MSP430AFE223 , MSP430AFE231 , MSP430AFE231 , MSP430AFE232 , MSP430AFE232 , MSP430AFE233 , MSP430AFE233 , MSP430AFE251 , MSP430AFE251 , MSP430AFE252 , MSP430AFE252 , MSP430AFE253 , MSP430AFE253 , MSP430BT5190 , MSP430BT5190 , MSP430F1101 , MSP430F1101 , MSP430F1101A , MSP430F1101A , MSP430F1111A , MSP430F1111A , MSP430F112 , MSP430F112 , MSP430F1121 , MSP430F1121 , MSP430F1121A , MSP430F1121A , MSP430F1122 , MSP430F1122 , MSP430F1132 , MSP430F1132 , MSP430F122 , MSP430F122 , MSP430F1222 , MSP430F1222 , MSP430F123 , MSP430F123 , MSP430F1232 , MSP430F1232 , MSP430F133 , MSP430F133 , MSP430F135 , MSP430F135 , MSP430F147 , MSP430F147 , MSP430F1471 , MSP430F1471 , MSP430F148 , MSP430F148 , MSP430F1481 , MSP430F1481 , MSP430F149 , MSP430F149 , MSP430F1491 , MSP430F1491 , MSP430F155 , MSP430F155 , MSP430F156 , MSP430F156 , MSP430F157 , MSP430F157 , MSP430F1610 , MSP430F1610 , MSP430F1611 , MSP430F1611 , MSP430F1612 , MSP430F1612 , MSP430F167 , MSP430F167 , MSP430F168 , MSP430F168 , MSP430F169 , MSP430F169 , MSP430F2001 , MSP430F2001 , MSP430F2002 , MSP430F2002 , MSP430F2003 , MSP430F2003 , MSP430F2011 , MSP430F2011 , MSP430F2012 , MSP430F2012 , MSP430F2013 , MSP430F2013 , MSP430F2013-EP , MSP430F2013-EP , MSP430F2101 , MSP430F2101 , MSP430F2111 , MSP430F2111 , MSP430F2112 , MSP430F2112 , MSP430F2121 , MSP430F2121 , MSP430F2122 , MSP430F2122 , MSP430F2131 , MSP430F2131 , MSP430F2132 , MSP430F2132 , MSP430F2232 , MSP430F2232 , MSP430F2234 , MSP430F2234 , MSP430F2252 , MSP430F2252 , MSP430F2254 , MSP430F2254 , MSP430F2272 , MSP430F2272 , MSP430F2274 , MSP430F2274 , MSP430F233 , MSP430F233 , MSP430F2330 , MSP430F2330 , MSP430F235 , MSP430F235 , MSP430F2350 , MSP430F2350 , MSP430F2370 , MSP430F2370 , MSP430F2410 , MSP430F2410 , MSP430F2416 , MSP430F2416 , MSP430F2417 , MSP430F2417 , MSP430F2418 , MSP430F2418 , MSP430F2419 , MSP430F2419 , MSP430F247 , MSP430F247 , MSP430F2471 , MSP430F2471 , MSP430F248 , MSP430F248 , MSP430F2481 , MSP430F2481 , MSP430F249 , MSP430F249 , MSP430F2491 , MSP430F2491 , MSP430F2616 , MSP430F2616 , MSP430F2617 , MSP430F2617 , MSP430F2618 , MSP430F2618 , MSP430F2619 , MSP430F2619 , MSP430F412 , MSP430F412 , MSP430F413 , MSP430F413 , MSP430F4132 , MSP430F4132 , MSP430F415 , MSP430F415 , MSP430F4152 , MSP430F4152 , MSP430F417 , MSP430F417 , MSP430F423 , MSP430F423 , MSP430F423A , MSP430F423A , MSP430F425 , MSP430F425 , MSP430F4250 , MSP430F4250 , MSP430F425A , MSP430F425A , MSP430F4260 , MSP430F4260 , MSP430F427 , MSP430F427 , MSP430F4270 , MSP430F4270 , MSP430F427A , MSP430F427A , MSP430F435 , MSP430F435 , MSP430F4351 , MSP430F4351 , MSP430F436 , MSP430F436 , MSP430F4361 , MSP430F4361 , MSP430F437 , MSP430F437 , MSP430F4371 , MSP430F4371 , MSP430F438 , MSP430F438 , MSP430F439 , MSP430F439 , MSP430F447 , MSP430F447 , MSP430F448 , MSP430F448 , MSP430F4481 , MSP430F4481 , MSP430F449 , MSP430F449 , MSP430F4491 , MSP430F4491 , MSP430F4616 , MSP430F4616 , MSP430F46161 , MSP430F46161 , MSP430F4617 , MSP430F4617 , MSP430F46171 , MSP430F46171 , MSP430F4618 , MSP430F4618 , MSP430F46181 , MSP430F46181 , MSP430F4619 , MSP430F4619 , MSP430F46191 , MSP430F46191 , MSP430F47126 , MSP430F47126 , MSP430F47127 , MSP430F47127 , MSP430F47163 , MSP430F47163 , MSP430F47166 , MSP430F47166 , MSP430F47167 , MSP430F47167 , MSP430F47173 , MSP430F47173 , MSP430F47176 , MSP430F47176 , MSP430F47177 , MSP430F47177 , MSP430F47183 , MSP430F47183 , MSP430F47186 , MSP430F47186 , MSP430F47187 , MSP430F47187 , MSP430F47193 , MSP430F47193 , MSP430F47196 , MSP430F47196 , MSP430F47197 , MSP430F47197 , MSP430F477 , MSP430F477 , MSP430F478 , MSP430F478 , MSP430F4783 , MSP430F4783 , MSP430F4784 , MSP430F4784 , MSP430F479 , MSP430F479 , MSP430F4793 , MSP430F4793 , MSP430F4794 , MSP430F4794 , MSP430F5212 , MSP430F5212 , MSP430F5214 , MSP430F5214 , MSP430F5217 , MSP430F5217 , MSP430F5219 , MSP430F5219 , MSP430F5222 , MSP430F5222 , MSP430F5224 , MSP430F5224 , MSP430F5229 , MSP430F5229 , MSP430F5232 , MSP430F5232 , MSP430F5234 , MSP430F5234 , MSP430F5237 , MSP430F5237 , MSP430F5239 , MSP430F5239 , MSP430F5242 , MSP430F5242 , MSP430F5244 , MSP430F5244 , MSP430F5247 , MSP430F5247 , MSP430F5249 , MSP430F5249 , MSP430F5252 , MSP430F5252 , MSP430F5253 , MSP430F5253 , MSP430F5254 , MSP430F5254 , MSP430F5255 , MSP430F5255 , MSP430F5256 , MSP430F5256 , MSP430F5257 , MSP430F5257 , MSP430F5258 , MSP430F5258 , MSP430F5259 , MSP430F5259 , MSP430F5304 , MSP430F5304 , MSP430F5308 , MSP430F5308 , MSP430F5309 , MSP430F5309 , MSP430F5310 , MSP430F5310 , MSP430F5324 , MSP430F5324 , MSP430F5325 , MSP430F5325 , MSP430F5326 , MSP430F5326 , MSP430F5327 , MSP430F5327 , MSP430F5328 , MSP430F5328 , MSP430F5329 , MSP430F5329 , MSP430F5333 , MSP430F5333 , MSP430F5335 , MSP430F5335 , MSP430F5336 , MSP430F5336 , MSP430F5338 , MSP430F5338 , MSP430F5340 , MSP430F5340 , MSP430F5341 , MSP430F5341 , MSP430F5342 , MSP430F5342 , MSP430F5358 , MSP430F5358 , MSP430F5359 , MSP430F5359 , MSP430F5418 , MSP430F5418 , MSP430F5418A , MSP430F5418A , MSP430F5419 , MSP430F5419 , MSP430F5419A , MSP430F5419A , MSP430F5435 , MSP430F5435 , MSP430F5435A , MSP430F5435A , MSP430F5436 , MSP430F5436 , MSP430F5436A , MSP430F5436A , MSP430F5437 , MSP430F5437 , MSP430F5437A , MSP430F5437A , MSP430F5438 , MSP430F5438 , MSP430F5438A , MSP430F5438A , MSP430F5500 , MSP430F5500 , MSP430F5501 , MSP430F5501 , MSP430F5502 , MSP430F5502 , MSP430F5503 , MSP430F5503 , MSP430F5504 , MSP430F5504 , MSP430F5505 , MSP430F5505 , MSP430F5506 , MSP430F5506 , MSP430F5507 , MSP430F5507 , MSP430F5508 , MSP430F5508 , MSP430F5509 , MSP430F5509 , MSP430F5510 , MSP430F5510 , MSP430F5513 , MSP430F5513 , MSP430F5514 , MSP430F5514 , MSP430F5515 , MSP430F5515 , MSP430F5517 , MSP430F5517 , MSP430F5519 , MSP430F5519 , MSP430F5521 , MSP430F5521 , MSP430F5522 , MSP430F5522 , MSP430F5524 , MSP430F5524 , MSP430F5525 , MSP430F5525 , MSP430F5526 , MSP430F5526 , MSP430F5527 , MSP430F5527 , MSP430F5528 , MSP430F5528 , MSP430F5529 , MSP430F5529 , MSP430F5630 , MSP430F5630 , MSP430F5631 , MSP430F5631 , MSP430F5632 , MSP430F5632 , MSP430F5633 , MSP430F5633 , MSP430F5634 , MSP430F5634 , MSP430F5635 , MSP430F5635 , MSP430F5636 , MSP430F5636 , MSP430F5637 , MSP430F5637 , MSP430F5638 , MSP430F5638 , MSP430F5658 , MSP430F5658 , MSP430F5659 , MSP430F5659 , MSP430F6433 , MSP430F6433 , MSP430F6435 , MSP430F6435 , MSP430F6436 , MSP430F6436 , MSP430F6438 , MSP430F6438 , MSP430F6458 , MSP430F6458 , MSP430F6459 , MSP430F6459 , MSP430F6630 , MSP430F6630 , MSP430F6631 , MSP430F6631 , MSP430F6632 , MSP430F6632 , MSP430F6633 , MSP430F6633 , MSP430F6634 , MSP430F6634 , MSP430F6635 , MSP430F6635 , MSP430F6636 , MSP430F6636 , MSP430F6637 , MSP430F6637 , MSP430F6638 , MSP430F6638 , MSP430F6658 , MSP430F6658 , MSP430F6659 , MSP430F6659 , MSP430F6745 , MSP430F6745 , MSP430F67451 , MSP430F67451 , MSP430F67451A , MSP430F67451A , MSP430F6745A , MSP430F6745A , MSP430F6746 , MSP430F6746 , MSP430F67461 , MSP430F67461 , MSP430F67461A , MSP430F67461A , MSP430F6746A , MSP430F6746A , MSP430F6747 , MSP430F6747 , MSP430F67471 , MSP430F67471 , MSP430F67471A , MSP430F67471A , MSP430F6747A , MSP430F6747A , MSP430F6748 , MSP430F6748 , MSP430F67481 , MSP430F67481 , MSP430F67481A , MSP430F67481A , MSP430F6748A , MSP430F6748A , MSP430F6749 , MSP430F6749 , MSP430F67491 , MSP430F67491 , MSP430F67491A , MSP430F67491A , MSP430F6749A , MSP430F6749A , MSP430F67621 , MSP430F67621 , MSP430F67621A , MSP430F67621A , MSP430F67641 , MSP430F67641 , MSP430F67641A , MSP430F67641A , MSP430F6765 , MSP430F6765 , MSP430F67651 , MSP430F67651 , MSP430F67651A , MSP430F67651A , MSP430F6765A , MSP430F6765A , MSP430F6766 , MSP430F6766 , MSP430F67661 , MSP430F67661 , MSP430F67661A , MSP430F67661A , MSP430F6766A , MSP430F6766A , MSP430F6767 , MSP430F6767 , MSP430F67671 , MSP430F67671 , MSP430F67671A , MSP430F67671A , MSP430F6767A , MSP430F6767A , MSP430F6768 , MSP430F6768 , MSP430F67681 , MSP430F67681 , MSP430F67681A , MSP430F67681A , MSP430F6768A , MSP430F6768A , MSP430F6769 , MSP430F6769 , MSP430F67691 , MSP430F67691 , MSP430F67691A , MSP430F67691A , MSP430F6769A , MSP430F6769A , MSP430F6775 , MSP430F6775 , MSP430F67751 , MSP430F67751 , MSP430F67751A , MSP430F67751A , MSP430F6775A , MSP430F6775A , MSP430F6776 , MSP430F6776 , MSP430F67761 , MSP430F67761 , MSP430F67761A , MSP430F67761A , MSP430F6776A , MSP430F6776A , MSP430F6777 , MSP430F6777 , MSP430F67771 , MSP430F67771 , MSP430F67771A , MSP430F67771A , MSP430F6777A , MSP430F6777A , MSP430F6778 , MSP430F6778 , MSP430F67781 , MSP430F67781 , MSP430F67781A , MSP430F67781A , MSP430F6778A , MSP430F6778A , MSP430F6779 , MSP430F6779 , MSP430F67791 , MSP430F67791 , MSP430F67791A , MSP430F67791A , MSP430F6779A , MSP430F6779A , MSP430FE423 , MSP430FE423 , MSP430FE4232 , MSP430FE4232 , MSP430FE423A , MSP430FE423A , MSP430FE4242 , MSP430FE4242 , MSP430FE425 , MSP430FE425 , MSP430FE4252 , MSP430FE4252 , MSP430FE425A , MSP430FE425A , MSP430FE427 , MSP430FE427 , MSP430FE4272 , MSP430FE4272 , MSP430FE427A , MSP430FE427A , MSP430FG4250 , MSP430FG4250 , MSP430FG4260 , MSP430FG4260 , MSP430FG4270 , MSP430FG4270 , MSP430FG437 , MSP430FG437 , MSP430FG438 , MSP430FG438 , MSP430FG439 , MSP430FG439 , MSP430FG4616 , MSP430FG4616 , MSP430FG4617 , MSP430FG4617 , MSP430FG4618 , MSP430FG4618 , MSP430FG4619 , MSP430FG4619 , MSP430FG477 , MSP430FG477 , MSP430FG478 , MSP430FG478 , MSP430FG479 , MSP430FG479 , MSP430FR2032 , MSP430FR2032 , MSP430FR2033 , MSP430FR2033 , MSP430FR2110 , MSP430FR2110 , MSP430FR2111 , MSP430FR2111 , MSP430FR2311 , MSP430FR2311 , MSP430FR2433 , MSP430FR2433 , MSP430FR2532 , MSP430FR2532 , MSP430FR2533 , MSP430FR2533 , MSP430FR2632 , MSP430FR2632 , MSP430FR2633 , MSP430FR2633 , MSP430FR4131 , MSP430FR4131 , MSP430FR4132 , MSP430FR4132 , MSP430FR5720 , MSP430FR5720 , MSP430FR5721 , MSP430FR5721 , MSP430FR5722 , MSP430FR5722 , MSP430FR5723 , MSP430FR5723 , MSP430FR5724 , MSP430FR5724 , MSP430FR5725 , MSP430FR5725 , MSP430FR5726 , MSP430FR5726 , MSP430FR5727 , MSP430FR5727 , MSP430FR5728 , MSP430FR5728 , MSP430FR5729 , MSP430FR5729 , MSP430FR5730 , MSP430FR5730 , MSP430FR5731 , MSP430FR5731 , MSP430FR5732 , MSP430FR5732 , MSP430FR5733 , MSP430FR5733 , MSP430FR5734 , MSP430FR5734 , MSP430FR5735 , MSP430FR5735 , MSP430FR5736 , MSP430FR5736 , MSP430FR5737 , MSP430FR5737 , MSP430FR5738 , MSP430FR5738 , MSP430FR5739 , MSP430FR5739 , MSP430FR5847 , MSP430FR5847 , MSP430FR58471 , MSP430FR58471 , MSP430FR5848 , MSP430FR5848 , MSP430FR5849 , MSP430FR5849 , MSP430FR5857 , MSP430FR5857 , MSP430FR5858 , MSP430FR5858 , MSP430FR5859 , MSP430FR5859 , MSP430FR5867 , MSP430FR5867 , MSP430FR58671 , MSP430FR58671 , MSP430FR5868 , MSP430FR5868 , MSP430FR5869 , MSP430FR5869 , MSP430FR5870 , MSP430FR5870 , MSP430FR5872 , MSP430FR5872 , MSP430FR58721 , MSP430FR58721 , MSP430FR5887 , MSP430FR5887 , MSP430FR5888 , MSP430FR5888 , MSP430FR5889 , MSP430FR5889 , MSP430FR58891 , MSP430FR58891 , MSP430FR5922 , MSP430FR5922 , MSP430FR59221 , MSP430FR59221 , MSP430FR5947 , MSP430FR5947 , MSP430FR59471 , MSP430FR59471 , MSP430FR5948 , MSP430FR5948 , MSP430FR5949 , MSP430FR5949 , MSP430FR5957 , MSP430FR5957 , MSP430FR5958 , MSP430FR5958 , MSP430FR5959 , MSP430FR5959 , MSP430FR5967 , MSP430FR5967 , MSP430FR5968 , MSP430FR5968 , MSP430FR5969 , MSP430FR5969 , MSP430FR5969-SP , MSP430FR5969-SP , MSP430FR59691 , MSP430FR59691 , MSP430FR5970 , MSP430FR5970 , MSP430FR5972 , MSP430FR5972 , MSP430FR59721 , MSP430FR59721 , MSP430FR5986 , MSP430FR5986 , MSP430FR5987 , MSP430FR5987 , MSP430FR5988 , MSP430FR5988 , MSP430FR5989 , MSP430FR5989 , MSP430FR5989-EP , MSP430FR5989-EP , MSP430FR59891 , MSP430FR59891 , MSP430FR5994 , MSP430FR5994 , MSP430FR6820 , MSP430FR6820 , MSP430FR6822 , MSP430FR6822 , MSP430FR68221 , MSP430FR68221 , MSP430FR6870 , MSP430FR6870 , MSP430FR6872 , MSP430FR6872 , MSP430FR68721 , MSP430FR68721 , MSP430FR6877 , MSP430FR6877 , MSP430FR6879 , MSP430FR6879 , MSP430FR68791 , MSP430FR68791 , MSP430FR6887 , MSP430FR6887 , MSP430FR6888 , MSP430FR6888 , MSP430FR6889 , MSP430FR6889 , MSP430FR68891 , MSP430FR68891 , MSP430FR6920 , MSP430FR6920 , MSP430FR6922 , MSP430FR6922 , MSP430FR69221 , MSP430FR69221 , MSP430FR6927 , MSP430FR6927 , MSP430FR69271 , MSP430FR69271 , MSP430FR6928 , MSP430FR6928 , MSP430FR6970 , MSP430FR6970 , MSP430FR6972 , MSP430FR6972 , MSP430FR69721 , MSP430FR69721 , MSP430FR6977 , MSP430FR6977 , MSP430FR6979 , MSP430FR6979 , MSP430FR69791 , MSP430FR69791 , MSP430FR6987 , MSP430FR6987 , MSP430FR6988 , MSP430FR6988 , MSP430FR6989 , MSP430FR6989 , MSP430FR69891 , MSP430FR69891 , MSP430FW423 , MSP430FW423 , MSP430FW425 , MSP430FW425 , MSP430FW427 , MSP430FW427 , MSP430FW428 , MSP430FW428 , MSP430FW429 , MSP430FW429 , MSP430G2001 , MSP430G2001 , MSP430G2101 , MSP430G2101 , MSP430G2102 , MSP430G2102 , MSP430G2111 , MSP430G2111 , MSP430G2112 , MSP430G2112 , MSP430G2121 , MSP430G2121 , MSP430G2131 , MSP430G2131 , MSP430G2132 , MSP430G2132 , MSP430G2152 , MSP430G2152 , MSP430G2153 , MSP430G2153 , MSP430G2201 , MSP430G2201 , MSP430G2202 , MSP430G2202 , MSP430G2203 , MSP430G2203 , MSP430G2210 , MSP430G2210 , MSP430G2211 , MSP430G2211 , MSP430G2212 , MSP430G2212 , MSP430G2213 , MSP430G2213 , MSP430G2221 , MSP430G2221 , MSP430G2230 , MSP430G2230 , MSP430G2231 , MSP430G2231 , MSP430G2232 , MSP430G2232 , MSP430G2233 , MSP430G2233 , MSP430G2252 , MSP430G2252 , MSP430G2253 , MSP430G2253 , MSP430G2302 , MSP430G2302 , MSP430G2303 , MSP430G2303 , MSP430G2312 , MSP430G2312 , MSP430G2313 , MSP430G2313 , MSP430G2332 , MSP430G2332 , MSP430G2333 , MSP430G2333 , MSP430G2352 , MSP430G2352 , MSP430G2353 , MSP430G2353 , MSP430G2402 , MSP430G2402 , MSP430G2403 , MSP430G2403 , MSP430G2412 , MSP430G2412 , MSP430G2413 , MSP430G2413 , MSP430G2432 , MSP430G2432 , MSP430G2433 , MSP430G2433 , MSP430G2444 , MSP430G2444 , MSP430G2452 , MSP430G2452 , MSP430G2453 , MSP430G2453 , MSP430G2513 , MSP430G2513 , MSP430G2533 , MSP430G2533 , MSP430G2544 , MSP430G2544 , MSP430G2553 , MSP430G2553 , MSP430G2744 , MSP430G2744 , MSP430G2755 , MSP430G2755 , MSP430G2855 , MSP430G2855 , MSP430G2955 , MSP430G2955 , MSP430L092 , MSP430L092 , MSP430TCH5E , MSP430TCH5E , MSP430V294 , MSP430V294

 

  1.   MSP Code Protection Features
    1.     Trademarks
    2. 1 Introduction
    3. 2 Locking JTAG Across Different MSP Families
      1. 2.1 Physical JTAG Fuse (F1xx/F2xx/F4xx)
      2. 2.2 Electronic Fuse or Lock Without Password
        1. 2.2.1 F5xx/F6xx Electronic Fuse Implementation
        2. 2.2.2 FR5xx/FR6xx Electronic Fuse Implementation (Lock without password)
        3. 2.2.3 FR2xx/FR4xx Electronic Fuse Implementation
        4. 2.2.4 MSP430i2xx Electronic Fuse Implementation – Start-Up Code (SUC)
      3. 2.3 JTAG Lock With Password (FR5xx/FR6xx)
        1. 2.3.1 Using JTAG Lock With Password in CCS
        2. 2.3.2 Using JTAG Lock With Password in IAR
    4. 3 IP Encapsulation (IPE)
      1. 3.1 IP Encapsulation Using the IPE Tool in CCS
        1. 3.1.1 CCS Linker File Features for IPE
        2. 3.1.2 Placing Code and Data in the IPE Sections in CCS
        3. 3.1.3 Enabling IPE in CCS Project Options
        4. 3.1.4 Viewing the Compiler-Selected IPE partitioning in CCS
        5. 3.1.5 Running and Testing IPE Code in CCS
          1. 3.1.5.1 Debug Settings With IPE in CCS
          2. 3.1.5.2 Testing IPE in CCS
      2. 3.2 IP Encapsulation Using the IPE Tool in IAR
        1. 3.2.1 IAR Linker File Features for IPE
        2. 3.2.2 Placing Code and Data in the IPE Sections in IAR
        3. 3.2.3 Enabling IPE in IAR Project Options
        4. 3.2.4 Viewing the Compiler-Selected IPE Partitioning in IAR
        5. 3.2.5 Running and Testing IPE Code in IAR
          1. 3.2.5.1 Debug Settings With IPE in IAR
          2. 3.2.5.2 Testing IPE in IAR
    5. 4 Bootloader (BSL) Security Features
      1. 4.1 Password Protection
      2. 4.2 Mass Erase on Incorrect Password
      3. 4.3 Disabling Bootloader (BSL)
    6. 5 References

2.1 Physical JTAG Fuse (F1xx/F2xx/F4xx)

MSP430F1xx, F2xx, and F4xx family devices JTAG can be secured through a physical JTAG security fuse. The fuse is blown by the programming tool after JTAG or SBW programming. The tool applies a fuse blowing voltage (6.5 V ±0.5 V) on the TEST pin (on devices with a TEST pin) or TDI pin (on devices without a TEST pin) [see MSP430 Programming Via the JTAG Interface (SLAU320)] for more details. Blowing the fuse completely disables the JTAG port and is not reversible, and further JTAG or SBW access is not possible. After the physical fuse is blown, the device is accessible only through the password-protected bootloader, if supported and enabled.