Emil's Projects & Reviews

OpenHardware & OpenSource

Unbricking a SEGGER J-Link v9 debug probe 15th May 2019
J-Link Genuine Segger


Case



PCB

Some time ago my SEGGER J-Link v9 stopped working. I wasn't sure what I did but I suspected it was a hardware failure. I've opened it and checked voltages with a multimeter and I couldn't find anything wrong. Then I've noticed it was using a familiar processor (STM32F205RC) and a PCB header which after I've reversed it turned out to be a JTAG connector:

I've soldered wires and connected my STLinkV2 and it was nothing wrong with the CPU, it was just empty! I have then tried to reflash it with an old version which I have found on the net and after programming my J-Link came back to life.

J-Link V9 memory map
TypeAddressLength
IVT0x080000000x200
Bootloader0x080002000x3e00
Signature0x0800b7000x100
Serial Nr0x0800bf004
Licenses0x0800bf200xc0
Config Data0x0800c0000x100
User Licenses0x0800c1000x3f00
FW IVT0x080100000x200
FW Code0x080102000x2fdfe
FW CRC160x0803fffe2
Code in RAM0x200000000x30d0
Data in RAM0x200030d00x10f30

The firmware which I have found had no bootloader so I had to program it at address 0x08010000 but at the same time I had to copy the interrupt vector table (IVT) also to 0x08000000 so that the firmware reset vector points to the main firmware.

When I've tried to use it the software was automatically trying to update it and since it had no bootloader it was failing. 

Connecting to J-Link via USB...Updating firmware:  J-Link V9 compiled Feb 22 2222 22:22:22
Replacing firmware: J-Link V9 compiled May 17 2119 09:50:41
FAILED: Failed to activate bootloader (timeout)

I have later discovered that the software was comparing the version in the J-Link with the latest version available inside the libjlinkarm library. The version string looks like this "J-Link V9 compiled May 17 2019 09:50:41". There are no numbers but instead the date is interpreted and compared. There are two such version strings, one for the bootloader and one for the firmware.

Bootloader version0x8000210
FW version0x8010210

To make the J-Link work without a bootloader all it was needed was to set the date in advance for the FW version and then the software wasn't trying to update it anymore. But I also wanted to have a relatively recent firmware so I've started to investigate where was this firmware stored and how could I extract it from the J-Link software.

It turned out that all the latest firmware versions for the SEGGER products are stored (some compressed, some not) in the libjlinkarm.so library: File: firmwares.txt
[ 0] [0x005400->0x005400] J-Trace ARM Rev.1
[ 1] [0x00f5e6->0x030000] J-Trace ARM CS Rev.1
[ 2] [0x014895->0x03c000] J-Trace Cortex-M Rev.3 
[ 3] [0x039aa9->0x100000] J-Trace PRO V1 Cortex-M 
[ 4] [0x000000->0x100000] J-Trace PRO V2 Cortex  (JTrace_PRO_V2_Cortex.bin)
[ 5] [0x000000->0x100000] J-Trace PRO V2 Cortex-M  (JTrace_PRO_V2_CortexM.bin)
[ 6] [0x000000->0x190000] J-Trace PRO V3 Cortex  (JTrace_PRO_V3_Cortex.bin)
[ 7] [0x000000->0x190000] J-Trace PRO V3 Cortex-M  (JTrace_PRO_V3_CortexM.bin)
[ 8] [0x000000->0x190000] J-Trace PRO V3 RISC-V  (JTrace_PRO_V3_RISCV.bin)
[ 9] [0x00e049->0x03c000] J-Link Ultra Rev.1 
[10] [0x02f5ac->0x070000] J-Link Ultra V4 
[11] [0x000000->0x100000] J-Link Ultra V5  (JLink_ULTRA_V5.bin)
[12] [0x000000->0x190000] J-Link Ultra V5-1  (JLink_ULTRA_V5_1.bin)
[13] [0x000000->0x190000] J-Link Ultra V6  (JLink_ULTRA_V6.bin)
[14] [0x015e28->0x030000] J-Link V9 
[15] [0x02c9cf->0x078000] J-Link V10 
[16] [0x000000->0x078000] J-Link V11  (JLink_V11.bin)
[17] [0x000000->0x078000] J-Link V12  (JLink_V12.bin)
[18] [0x000000->0x018800] J-Link EDU Mini V1  (JLinkEDUMini_V1.bin)
[19] [0x000000->0x078000] J-Link WiFi-V1  (JLink_WiFi_V1.bin)
[20] [0x005400->0x005400] Rev.5
[21] [0x006e00->0x006e00] J-Link ARM V6 
[22] [0x006e00->0x006e00] J-Link ARM V7 
[23] [0x00dc00->0x00dc00] J-Link ARM V8 
[24] [0x00dc00->0x00dc00] J-Link ARM-OB SAM7 
[25] [0x008094->0x00dc00] J-Link OB RX200 V1 
[26] [0x00d89c->0x00dc00] J-Link ARM Lite V8 
[27] [0x0155d0->0x018800] J-Link Lite V9 
[28] [0x00a7d8->0x00dc00] J-Link Lite-Cortex-M V8 
[29] [0x01047c->0x018800] J-Link Lite-Cortex-M V9 
[30] [0x00854c->0x00dc00] J-Link LITE-Cortex-M-5V 
[31] [0x000000->0x019c00] J-Link Lite Synergy  (JLink_Lite_Synergy.bin)
[32] [0x005000->0x005000] J-Link ARM-LPC Rev.1 
[33] [0x018000->0x018000] J-Link ARM-LPC2146 Rev.2 
[34] [0x008980->0x020000] J-Link Lite-XMC4000 Rev.1 
[35] [0x00f6ec->0x020000] J-Link Lite-XMC4200 Rev.1 
[36] [0x00d378->0x018000] J-Link Lite-ADI Rev.1 
[37] [0x010000->0x010000] J-Link Lite-LPC Rev.1 
[38] [0x006000->0x008000] J-Link ARM-STR711
[39] [0x005c00->0x005c00] J-Link ARM-OB STM32 
[40] [0x00b800->0x00b800] J-Link Lite-STM32 Rev.1 
[41] [0x006e00->0x006e00] J-Link CF V1 
[42] [0x00b800->0x00b800] J-Link Lite-FSL V1 
[43] [0x0387c4->0x060000] J-Link / Flasher ATE Mainboard V1 
[44] [0x052b44->0x060000] J-Link / Flasher ATE Module V1 
[45] [0x015b4a->0x000000] J-Link ARM / Flasher ARM V2 
[46] [0x021482->0x000000] J-Link ARM / Flasher ARM V3 
[47] [0x03e568->0x000000] J-Link ARM / Flasher ARM V4 
[48] [0x000000->0x000000] J-Link / Flasher ARM V5  (FlasherARM_V5.bin)
[49] [0x000000->0x000000] J-Link / Flasher ARM V5-1  (FlasherARM_V5_1.bin)
[50] [0x02c516->0x000000] J-Link / Flasher Portable V1 
[51] [0x03b833->0x000000] J-Link / Flasher Portable Plus V1 
[52] [0x000000->0x000000] J-Link / Flasher Portable PLUS V5  (Flasher_Portable_PLUS_V5.bin)
[53] [0x01fa39->0x000000] J-Link RX / Flasher RX V1 
[54] [0x038fc5->0x000000] J-Link RX / Flasher RX V4 
[55] [0x01deff->0x000000] J-Link PPC / Flasher PPC V1 
[56] [0x037383->0x000000] J-Link PPC / Flasher PPC V4 
[57] [0x04483d->0x000000] J-Link PRO / Flasher PRO V4 
[58] [0x000000->0x000000] J-Link / Flasher PRO V5  (FlasherPRO_V5.bin)
[59] [0x000000->0x000000] J-Link / Flasher PRO V5-1  (FlasherPRO_V5_1.bin)
[60] [0x000000->0x000000] J-Link / Flasher Compact V5  (FlasherCompact_V5.bin)
[61] [0x0132ec->0x030000] J-Link ARM-Pro V1.x 
[62] [0x01403b->0x030000] J-Link ARM-Pro V3.x 
[63] [0x02f59f->0x070000] J-Link Pro V4 
[64] [0x000000->0x100000] J-Link Pro V5  (JLink_PRO_V5.bin)
[65] [0x000000->0x190000] J-Link Pro V5-1  (JLink_PRO_V5_1.bin)
[66] [0x000000->0x190000] J-Link Pro V6  (JLink_PRO_V6.bin)
[67] [0x004f30->0x038000] J-Link OB RX6xx V1 
[68] [0x0096c2->0x038000] J-Link OB RX621-ARM-SWD V1 
[69] [0x00488d->0x038000] J-Link OB-RX621-RX1xx V1 
[70] [0x00baad->0x039000] J-Link MCU-Link V1 
[71] [0x000000->0x034000] J-Link OB-Apollo4-CortexM  (JLink_OB_Apollo4_CortexM.bin)
[72] [0x000000->0x018800] J-Link OB-K22-Cortex-A  (JLink_OB_K22_CortexA.bin)
[73] [0x000000->0x018800] J-Link OB-K22-Cortex-M  (JLink_OB_K22_CortexM.bin)
[74] [0x000000->0x018800] J-Link OB-K22-RISCV  (JLink_OB_K22_RISCV.bin)
[75] [0x000000->0x01a000] J-Link OB-K22-NordicSemi  (JLink_OB_K22_NordicSemi.bin)
[76] [0x000000->0x018800] J-Link OB-K22-Qorvo  (JLink_OB_K22_Qorvo.bin)
[77] [0x0179d0->0x018800] J-Link OB-K22-SiFive 
[78] [0x000000->0x0f9000] J-Link OB-nRF5340-NordicSemi  (JLink_OB_nRF5340_NordicSemi.bin)
[79] [0x000000->0x019c00] J-Link OB-S124  (JLink_OB_S124.bin)
[80] [0x000000->0x019c00] J-Link Lite-S124  (JLink_Lite_S124.bin)
[81] [0x000000->0x016e00] J-Link OB-SAM3U128-V2-NordicSemi  (JLink_OB_SAM3U128_V2_NordicSemi.bin)
[82] [0x000000->0x01c000] J-Link OB-SAM3U128 V1  (JLink_OB_SAM3U128_V1.bin)
[83] [0x000000->0x019e00] J-Link OB-SAM3U128 V3  (JLink_OB_SAM3U128_V3.bin)
[84] [0x000000->0x01b800] J-Link OB-STM32F103 V1  (JLink_OB_STM32F103.bin)
[85] [0x008153->0x00b800] J-Link OB-STM32F072-CortexAR 
[86] [0x0080c0->0x00b800] J-Link OB-STM32F072-CortexM 
[87] [0x00c62f->0x01a000] J-Link OB-STM32F072-128KB-CortexM 
[88] [0x009114->0x01c000] J-Link OB-MB9AF312K-Spansion 
[89] [0x00c3e9->0x0f0000] J-Link OB-STM32F4-Arduino V1 
[90] [0x000000->0x036000] J-Link OB-RA4M2  (JLink_OB_RA4M2_Renesas.bin)
[91] [0x000000->0x036000] J-Link OB-RA4M2-CortexM (JLink_OB_RA4M2_CortexM.bin)
[92] [0x000000->0x036000] J-Link OB-RA4M2-RISCV (JLink_OB_RA4M2_RISCV.bin)
[93] [0x000000->0x036000] J-Link OB-RA4M2-Full (JLink_OB_RA4M2_Full.bin)
[94] [0x000000->0x01a000] J-Link OB-CALLIOPE-MINI V2.1  (JLink_OB_Calliope_MINI_V2_1.bin)

Finding the above table in the library was easy but unfortunately some of the firmwares are compressed (seems that the ZIP format is used) and it has headers and tables at various address and it is not easy to decompress and extract the firmware.

Instead I've took advantage of the dlopen function (in Linux) and loaded that library in my software. The library exports the JLINK_GetEmbeddedFWString function which uncompresses the firmware to read the date string. I then intercept the malloc function and simply call that extract function and dump the memory allocated by malloc before the free is called. This allows me to extract any of the stored firmwares.

After version 720 the firmware date code was changed and it only decompresses the first 1 KB of code. My quick solution to this was to restore the previous behaviour and expand the entire firmware. If you follow the JLINK_GetEmbeddedFWString function you will find two calls to malloc, The size parameter of the second call is in r12d (in linux x64 code) and I've restored that value to the actual decompressed size as ilustrated in the assembler code bellow (one assembler instruction is replaced in libjlinkarm.so): File: patch
------------------- Original Code ----------------------------------------------------
8B 78 24	      mov     edi, [rax+24h]
45 8D A6 7F 04 00 00  lea     r12d, [r14+47Fh]
48 8D 35 7E 12 1F 00  lea     rsi, aEmu_firmwareCo ; "EMU_Firmware: Compress workspace"
41 81 E4 00 FC FF FF  and     r12d, 0FFFFFC00h
01 FF		      add     edi, edi
E8 A0 60 0F 00	      call    cc_malloc
48 8D 35 9F 0A 1F 00  lea     rsi, aEmu_firmwareFw ; "EMU_Firmware: FW image buffer"
44 89 E7	      mov     edi, r12d
49 89 C7	      mov     r15, rax
E8 8E 60 0F 00	      call    cc_malloc
49 89 C5	      mov     r13, rax
-------------------- Patched Code (mov r12d) -----------------------------------------
8B 78 24	      mov     edi, [rax+24h]
45 8D A6 7F 04 00 00  lea     r12d, [r14+47Fh]
48 8D 35 7E 12 1F 00  lea     rsi, aEmu_firmwareCo ; "EMU_Firmware: Compress workspace"
44 8B 60 1C	      mov     r12d, [rax+1Ch]  <-------- replaced instruction
90		      nop
90		      nop
90		      nop
01 FF		      add     edi, edi
E8 A0 60 0F 00	      call    cc_malloc
48 8D 35 9F 0A 1F 00  lea     rsi, aEmu_firmwareFw ; "EMU_Firmware: FW image buffer"
44 89 E7	      mov     edi, r12d
49 89 C7	      mov     r15, rax
E8 8E 60 0F 00	      call    cc_malloc
49 89 C5	      mov     r13, rax
-------------------- Example: Differences for JLink_Linux_V784f_x86_64 ---------------
libjlinkarm.so.7.84.6
002f1cf2: 41 44
002f1cf3: 81 8b
002f1cf4: e4 60
002f1cf5: 00 1c
002f1cf6: fc 90
002f1cf7: ff 90
002f1cf8: ff 90
This is automatically done by dump_segger_fw in memory after it loads the libjlinkarm.so (this may break in future versions). Without patching your .dll/.so library the dump_segger_fw program will only be able to extract the plain uncompressed firmwares.

You can get the dump_segger_fw source code and linux executable. This program also prompts for a serial number and builds a complete flash image with the correct CRC16 ready to be programmed (but only for the J-Link v9 probe). If you also have a previously extracted bootloader file jlink_v9_bootloader.bin (more about this later) then the bootloader is included as part of the image, otherwise the IVT copy trick is used. The serial number of a probe can be any 4 bytes number but in practice the decimal version of this serial usually includes the hardware revision of your probe. Example: for hardware revision 9.4 the serial number is in the format 26940xxxx.

J-Link Serial Number

I have used my restored J-Link probe with the date set in advance for a while but then I've seen a colleague using a chinese clone which was updating normally. This intrigued me because that meant the clone had a bootloader, which is not present anywhere in the SEGGER software, it is only programmed once at manufacture time.

J-Link Segger Clones
Case (1)
Case (2)
PCB v9.4
PCB v9.6
PCB v9.7
PCB v9.9

I have found these schematics for the chinese clones: JlinkV93_sch and JlinkV95_sch

I've quickly purchased a clone myself and hooked the STLinkV2 to it. Then surprise, the flash memory was protected. I could stop the processor and dump its RAM (even modify it) but as soon as I was trying to read from the flash memory (either directly or by inserting code in RAM) I was getting CPU exceptions. Dumping the RAM turned up useful because a small part of the flash is expanded and executed from RAM (when upgrading or adding licenses) and also I had a snapshot of the variable values.

My first idea of extracting the bootloader was to overwrite the firmware with my own program which will then dump the bootloader to USB. I've made a project J-Link-Dump-Bootloader which I've tested on my original J-Link which had no valid bootloader just to make sure it was working properly (and it did). Then I've used my dump_segger_fw (compiled with a LIB_OVERLAY define) to overlay my created binary in the libjlinkarm library and let the SEGGER software do the update. Unfortunately this didn't work and I had to manually restore the main firmware back. I have later found out that this was failing because the firmware should have been padded to the full length (0x30000) which I didn't know at the time.

Connecting to J-Link via USB...Updating firmware:  J-Link V9 compiled Feb 22 2222 22:22:22
Replacing firmware: J-Link V9 compiled May 17 2019 09:50:41
FAILED: Communication timed out: Requested 1 bytes, received 0 bytes !
Communication timed out after firmware update
I've then captured the USB transactions during a firmware update: File: USB-Capture_Update_Firmware.html






Type
Title
Device
Endpoint
Direction
Status
Size
Data
Text




Bus state
Reset 1.4 seconds




0






Bus state
Suspended 143.0 milliseconds




0






Bus state
Reset 54.8 milliseconds




0






Bus state
High speed handshake




0






Container
GetDescriptor (Device)
0 (16)
0
In
OK
18
12 01 00 02





Transaction
SETUP
0 (16)
0
Out
ACK
8
80 06 00 01





Transaction
IN
0 (16)
0
In
ACK
18
12 01 00 02





Transaction
OUT
0 (16)
0
Out
ACK
0






Bus state
Reset 54.8 milliseconds




0






Bus state
High speed handshake




0






Container
SetAddress (16)
0 (16)
0
Out
OK
0






Transaction
SETUP
0 (16)
0
Out
ACK
8
00 05 10 00





Transaction
IN
0 (16)
0
In
ACK
0






Container
GetDescriptor (Device)
16
0
In
OK
18
12 01 00 02





Transaction
SETUP
16
0
Out
ACK
8
80 06 00 01





Transaction
IN
16
0
In
ACK
18
12 01 00 02





Transaction
OUT
16
0
Out
ACK
0






Container
GetDescriptor (Device qualifier)
16
0
In
STALLED
0






Transaction
SETUP
16
0
Out
ACK
8
80 06 00 06





Transaction
IN
16
0
In
STALL
0






Container
GetDescriptor (Device qualifier)
16
0
In
STALLED
0






Transaction
SETUP
16
0
Out
ACK
8
80 06 00 06





Transaction
IN
16
0
In
STALL
0






Container
GetDescriptor (Device qualifier)
16
0
In
STALLED
0






Transaction
SETUP
16
0
Out
ACK
8
80 06 00 06





Transaction
IN
16
0
In
STALL
0






Container
GetDescriptor (Configuration)
16
0
In
OK
9
09 02 62 00





Transaction
SETUP
16
0
Out
ACK
8
80 06 00 02





Transaction
IN
16
0
In
ACK
9
09 02 62 00





Transaction
OUT
16
0
Out
ACK
0






Container
GetDescriptor (Configuration)
16
0
In
OK
98
09 02 62 00





Transaction
SETUP
16
0
Out
ACK
8
80 06 00 02





Transaction
IN
16
0
In
ACK
64
09 02 62 00





Transaction
IN
16
0
In
ACK
34
02 40 00 01





Transaction
OUT
16
0
Out
ACK
0






Container
GetDescriptor (String lang IDs)
16
0
In
OK
4
04 03 09 04





Transaction
SETUP
16
0
Out
ACK
8
80 06 00 03





Transaction
IN
16
0
In
ACK
4
04 03 09 04





Transaction
OUT
16
0
Out
ACK
0






Container
GetDescriptor (String iProduct)
16
0
In
OK
14
0E 03 4A 00
J.-.L.i.n.k.




Transaction
SETUP
16
0
Out
ACK
8
80 06 02 03





Transaction
IN
16
0
In
ACK
14
0E 03 4A 00
J.-.L.i.n.k.




Transaction
OUT
16
0
Out
ACK
0






Container
GetDescriptor (String iManufacturer)
16
0
In
OK
14
0E 03 53 00
S.E.G.G.E.R.




Transaction
SETUP
16
0
Out
ACK
8
80 06 01 03





Transaction
IN
16
0
In
ACK
14
0E 03 53 00
S.E.G.G.E.R.




Transaction
OUT
16
0
Out
ACK
0






Container
GetDescriptor (String iSerialNumber)
16
0
In
OK
26
1A 03 30 00
0.0.0.5.8.3.6.4.8.1.2.5.




Transaction
SETUP
16
0
Out
ACK
8
80 06 03 03





Transaction
IN
16
0
In
ACK
26
1A 03 30 00
0.0.0.5.8.3.6.4.8.1.2.5.




Transaction
OUT
16
0
Out
ACK
0






Container
SetConfiguration (1)
16
0
Out
OK
0






Transaction
SETUP
16
0
Out
ACK
8
00 09 01 00





Transaction
IN
16
0
In
ACK
0






Container
GetDescriptor (String iConfiguration)
16
0
In
OK
28
1C 03 43 00
C.o.n.f.i.g.u.r.a.t.i.o.n.




Transaction
SETUP
16
0
Out
ACK
8
80 06 04 03





Transaction
IN
16
0
In
ACK
28
1C 03 43 00
C.o.n.f.i.g.u.r.a.t.i.o.n.




Transaction
OUT
16
0
Out
ACK
0






Container
GetDescriptor (String iInterface)
16
0
In
OK
8
08 03 43 00
C.D.C.




Transaction
SETUP
16
0
Out
ACK
8
80 06 05 03





Transaction
IN
16
0
In
ACK
8
08 03 43 00
C.D.C.




Transaction
OUT
16
0
Out
ACK
0






Container
SetLineCoding
16
0
Out
OK
7
80 25 00 00





Transaction
SETUP
16
0
Out
ACK
8
21 20 00 00





Transaction
OUT
16
0
Out
ACK
7
80 25 00 00





Transaction
IN
16
0
In
ACK
0






Container
GetDescriptor (String iInterface)
16
0
In
OK
38
26 03 43 00
&.C.D.C. .D.A.T.A. .i.n.t.e.r.f.a.c.e.




Transaction
SETUP
16
0
Out
ACK
8
80 06 06 03





Transaction
IN
16
0
In
ACK
38
26 03 43 00
&.C.D.C. .D.A.T.A. .i.n.t.e.r.f.a.c.e.




Transaction
OUT
16
0
Out
ACK
0






Container
GetDescriptor (String iInterface)
16
0
In
OK
30
1E 03 42 00
B.U.L.K. .i.n.t.e.r.f.a.c.e.




Transaction
SETUP
16
0
Out
ACK
8
80 06 07 03





Transaction
IN
16
0
In
ACK
30
1E 03 42 00
B.U.L.K. .i.n.t.e.r.f.a.c.e.




Transaction
OUT
16
0
Out
ACK
0






Container
OUT Bulk transfer
16
3
Out
OK
1
01





Transaction
OUT
16
3
Out
ACK
1
01





Container
IN Bulk transfer
16
3
In
OK
2
70 00





Transaction
IN
16
3
In
ACK
2
70 00





Container
IN Bulk transfer
16
3
In
OK
112
4A 2D 4C 69
J-Link V9 compiled May 17 2019 09:50:41.Copyright 2003-2012 SEGGER: www.segger.com




Transaction
IN
16
3
In
ACK
64
4A 2D 4C 69
J-Link V9 compiled May 17 2019 09:50:41.Copyright 2003-2012 SEGG




Transaction
IN
16
3
In
ACK
48
45 52 3A 20
ER: www.segger.com




Container
OUT Bulk transfer
16
3
Out
OK
1
01





Transaction
OUT
16
3
Out
ACK
1
01





Container
IN Bulk transfer
16
3
In
OK
2
70 00





Transaction
IN
16
3
In
ACK
2
70 00





Container
IN Bulk transfer
16
3
In
OK
112
4A 2D 4C 69
J-Link V9 compiled May 17 2019 09:50:41.Copyright 2003-2012 SEGGER: www.segger.com




Transaction
IN
16
3
In
ACK
64
4A 2D 4C 69
J-Link V9 compiled May 17 2019 09:50:41.Copyright 2003-2012 SEGG




Transaction
IN
16
3
In
ACK
48
45 52 3A 20
ER: www.segger.com




Container
OUT Bulk transfer
16
3
Out
OK
1
01





Transaction
OUT
16
3
Out
ACK
1
01





Container
IN Bulk transfer
16
3
In
OK
2
70 00





Transaction
IN
16
3
In
ACK
2
70 00





Container
IN Bulk transfer
16
3
In
OK
112
4A 2D 4C 69
J-Link V9 compiled May 17 2019 09:50:41.Copyright 2003-2012 SEGGER: www.segger.com




Transaction
IN
16
3
In
ACK
64
4A 2D 4C 69
J-Link V9 compiled May 17 2019 09:50:41.Copyright 2003-2012 SEGG




Transaction
IN
16
3
In
ACK
48
45 52 3A 20
ER: www.segger.com




Container
OUT Bulk transfer
16
3
Out
OK
1
06





Transaction
OUT
16
3
Out
ACK
1
06





Container
IN Bulk transfer
16
3
In
OK
1
01





Transaction
IN
16
3
In
ACK
1
01





Bus state
Reset 70.9 milliseconds




0






Bus state
High speed handshake




0






Bus state
Suspended 145.1 milliseconds




0






Bus state
Reset 54.8 milliseconds




0






Bus state
High speed handshake




0






Container
GetDescriptor (Device)
0 (14)
0
In
OK
18
12 01 00 02





Transaction
SETUP
0 (14)
0
Out
ACK
8
80 06 00 01





Transaction
IN
0 (14)
0
In
ACK
18
12 01 00 02





Transaction
OUT
0 (14)
0
Out
ACK
0






Bus state
Reset 54.8 milliseconds




0






Bus state
High speed handshake




0






Container
SetAddress (14)
0 (14)
0
Out
OK
0






Transaction
SETUP
0 (14)
0
Out
ACK
8
00 05 0E 00





Transaction
IN
0 (14)
0
In
ACK
0






Container
GetDescriptor (Device)
14
0
In
OK
18
12 01 00 02





Transaction
SETUP
14
0
Out
ACK
8
80 06 00 01





Transaction
IN
14
0
In
ACK
18
12 01 00 02





Transaction
OUT
14
0
Out
ACK
0






Container
GetDescriptor (Device qualifier)
14
0
In
STALLED
0






Transaction
SETUP
14
0
Out
ACK
8
80 06 00 06





Transaction
IN
14
0
In
STALL
0






Container
GetDescriptor (Device qualifier)
14
0
In
STALLED
0






Transaction
SETUP
14
0
Out
ACK
8
80 06 00 06





Transaction
IN
14
0
In
STALL
0






Container
GetDescriptor (Device qualifier)
14
0
In
STALLED
0






Transaction
SETUP
14
0
Out
ACK
8
80 06 00 06





Transaction
IN
14
0
In
STALL
0






Container
GetDescriptor (Configuration)
14
0
In
OK
9
09 02 20 00





Transaction
SETUP
14
0
Out
ACK
8
80 06 00 02





Transaction
IN
14
0
In
ACK
9
09 02 20 00





Transaction
OUT
14
0
Out
ACK
0






Container
GetDescriptor (Configuration)
14
0
In
OK
32
09 02 20 00





Transaction
SETUP
14
0
Out
ACK
8
80 06 00 02





Transaction
IN
14
0
In
ACK
32
09 02 20 00





Transaction
OUT
14
0
Out
ACK
0






Container
GetDescriptor (String lang IDs)
14
0
In
OK
4
04 03 09 04





Transaction
SETUP
14
0
Out
ACK
8
80 06 00 03





Transaction
IN
14
0
In
ACK
4
04 03 09 04





Transaction
OUT
14
0
Out
ACK
0






Container
GetDescriptor (String iProduct)
14
0
In
OK
14
0E 03 4A 00
J.-.L.i.n.k.




Transaction
SETUP
14
0
Out
ACK
8
80 06 02 03





Transaction
IN
14
0
In
ACK
14
0E 03 4A 00
J.-.L.i.n.k.




Transaction
OUT
14
0
Out
ACK
0






Container
GetDescriptor (String iManufacturer)
14
0
In
OK
14
0E 03 53 00
S.E.G.G.E.R.




Transaction
SETUP
14
0
Out
ACK
8
80 06 01 03





Transaction
IN
14
0
In
ACK
14
0E 03 53 00
S.E.G.G.E.R.




Transaction
OUT
14
0
Out
ACK
0






Container
GetDescriptor (String iSerialNumber)
14
0
In
OK
26
1A 03 30 00
0.0.0.5.8.3.6.4.8.1.2.5.




Transaction
SETUP
14
0
Out
ACK
8
80 06 03 03





Transaction
IN
14
0
In
ACK
26
1A 03 30 00
0.0.0.5.8.3.6.4.8.1.2.5.




Transaction
OUT
14
0
Out
ACK
0






Container
SetConfiguration (1)
14
0
Out
OK
0






Transaction
SETUP
14
0
Out
ACK
8
00 09 01 00





Transaction
IN
14
0
In
ACK
0






Container
OUT Bulk transfer
14
1
Out
OK
1
01





Transaction
OUT
14
1
Out
ACK
1
01





Container
IN Bulk transfer
14
1
In
OK
2
70 00





Transaction
IN
14
1
In
ACK
2
70 00





Container
IN Bulk transfer
14
1
In
OK
112
4A 2D 4C 69
J-Link V9 compiled Oct 12 2012 BTL     .Copyright 2003-2012 SEGGER: www.segger.com




Transaction
IN
14
1
In
ACK
64
4A 2D 4C 69
J-Link V9 compiled Oct 12 2012 BTL     .Copyright 2003-2012 SEGG




Transaction
IN
14
1
In
ACK
48
45 52 3A 20
ER: www.segger.com




Container
OUT Bulk transfer
14
1
Out
OK
1
06





Transaction
OUT
14
1
Out
ACK
1
06





Container
IN Bulk transfer
14
1
In
OK
1
00





Transaction
IN
14
1
In
ACK
1
00





Container
OUT Bulk transfer
14
1
Out
OK
2
F8 11





Transaction
OUT
14
1
Out
ACK
2
F8 11





Container
OUT Bulk transfer
14
1
Out
OK
4600
00 80 01 20
J-Link V9 compiled Feb 22 2222 22:22:22.Copyright 2003-2012 SEGGER: www.segger.com




Transaction
OUT
14
1
Out
ACK
64
00 80 01 20





Transaction
OUT
14
1
Out
ACK
64
B9 11 01 08





Transaction
OUT
14
1
Out
ACK
64
B9 11 01 08





Transaction
OUT
14
1
Out
ACK
64
B9 11 01 08





Transaction
OUT
14
1
Out
ACK
64
B9 11 01 08





Transaction
OUT
14
1
Out
ACK
64
B9 11 01 08





Transaction
OUT
14
1
Out
ACK
64
B9 11 01 08





Transaction
OUT
14
1
Out
ACK
64
FF FF FF FF





Transaction
OUT
14
1
Out
ACK
64
00 00 00 00
J-Link V9 compiled Feb 22 2222 22:22:22.Copyrigh




Transaction
OUT
14
1
Out
ACK
64
74 20 32 30
t 2003-2012 SEGGER: www.segger.com




Transaction
OUT
14
1
Out
ACK
64
FF FF FF FF





Transaction
OUT
14
1
Out
ACK
64
FF FF FF FF





Transaction
OUT
14
1
Out
ACK
64
03 48 04 4B





Transaction
OUT
14
1
Out
ACK
64
10 B5 06 4C





Transaction
OUT
14
1
Out
ACK
64
08 00 00 20





Transaction
OUT
14
1
Out
ACK
64
EC 11 01 08





Transaction
OUT
14
1
Out
ACK
64
2D E9 F0 47





Transaction
OUT
14
1
Out
ACK
64
08 F9 21 0C





Transaction
OUT
14
1
Out
ACK
64
80 F0 07 81





Transaction
OUT
14
1
Out
ACK
64
83 F7 00 2F





Transaction
OUT
14
1
Out
ACK
64
F8 FE 08 FB





Transaction
OUT
14
1
Out
ACK
64
00 F1 FF 33





Transaction
OUT
14
1
Out
ACK
64
09 FB 08 FA





Transaction
OUT
14
1
Out
ACK
64
89 B2 41 EA





Transaction
OUT
14
1
Out
ACK
64
22 FA 07 F3





Transaction
OUT
14
1
Out
ACK
64
02 F4 07 D9





Transaction
OUT
14
1
Out
ACK
64
0E 01 40 EA





Transaction
OUT
14
1
Out
ACK
64
02 0E 2B 44





Transaction
OUT
14
1
Out
ACK
64
CD E9 02 44





Transaction
OUT
14
1
Out
ACK
64
CD E9 06 44





Transaction
OUT
14
1
Out
ACK
64
18 63 18 6B





Transaction
OUT
14
1
Out
ACK
64
CD E9 05 35





Transaction
OUT
14
1
Out
ACK
64
00 F0 7A FB





Transaction
OUT
14
1
Out
ACK
64
01 22 4F F4





Transaction
OUT
14
1
Out
ACK
64
70 47 00 BF





Transaction
OUT
14
1
Out
ACK
64
70 47 00 BF





Transaction
OUT
14
1
Out
ACK
64
1A 60 1A 68





Transaction
OUT
14
1
Out
ACK
64
20 00 00 20





Transaction
OUT
14
1
Out
ACK
64
0C 02 04 2A





Transaction
OUT
14
1
Out
ACK
64
9F 07 39 D4





Transaction
OUT
14
1
Out
ACK
64
01 F0 0C 01





Transaction
OUT
14
1
Out
ACK
64
29 D0 91 68





Transaction
OUT
14
1
Out
ACK
64
23 69 21 F0





Transaction
OUT
14
1
Out
ACK
64
52 D8 6B 6F





Transaction
OUT
14
1
Out
ACK
64
D0 E7 00 23





Transaction
OUT
14
1
Out
ACK
64
22 7A 1A 70





Transaction
OUT
14
1
Out
ACK
64
F8 00 8A 40





Transaction
OUT
14
1
Out
ACK
64
7F F5 1A AF





Transaction
OUT
14
1
Out
ACK
64
B2 D8 2B 68





Transaction
OUT
14
1
Out
ACK
64
01 3A 43 EA





Transaction
OUT
14
1
Out
ACK
64
8B 68 03 F0





Transaction
OUT
14
1
Out
ACK
64
08 BD 08 48





Transaction
OUT
14
1
Out
ACK
64
8B 42 01 D0





Transaction
OUT
14
1
Out
ACK
64
0D 46 20 D5





Transaction
OUT
14
1
Out
ACK
64
B3 EB 82 0F





Transaction
OUT
14
1
Out
ACK
64
5D FF 14 4B





Transaction
OUT
14
1
Out
ACK
64
9E 03 A8 D4





Transaction
OUT
14
1
Out
ACK
64
00 ED 00 E0





Transaction
OUT
14
1
Out
ACK
64
D2 B2 0A DB





Transaction
OUT
14
1
Out
ACK
64
70 47 00 BF





Transaction
OUT
14
1
Out
ACK
64
00 25 D1 F8





Transaction
OUT
14
1
Out
ACK
64
02 EA 0A 0A





Transaction
OUT
14
1
Out
ACK
64
03 F1 80 43





Transaction
OUT
14
1
Out
ACK
64
00 F0 83 80





Transaction
OUT
14
1
Out
ACK
64
04 30 A7 03





Transaction
OUT
14
1
Out
ACK
64
6F 00 BA 40





Transaction
OUT
14
1
Out
ACK
64
46 EA 0C 06





Transaction
OUT
14
1
Out
ACK
64
03 27 07 FA
www.segg




Transaction
OUT
14
1
Out
ACK
64
65 72 2E 63
er.com.Copyright (c) 2003 - 2012 SEGGER Microcontroller. May be




Transaction
OUT
14
1
Out
ACK
64
75 73 65 64
used in original J-Links and products manufactured under license




Transaction
OUT
14
1
Out
ACK
64
20 6F 6E 6C
only




Transaction
OUT
14
1
Out
ACK
56
F8 BC 08 BC





Container
ClearFeature (Endpoint 1 OUT, Halt)
14
0
Out
OK
0






Transaction
SETUP
14
0
Out
ACK
8
02 01 00 00





Transaction
IN
14
0
In
ACK
0

You can see that the device is enumerated as "J-Link Plus" then command "01" is send to retrieve the version string. If there is a newer version available then command "06" is sent. This resets the device and executes the bootloader which now enumerates as "J-Link ARM". The entire firmware is then transmitted and the bootloader takes care to flash it to the proper address.

VID:PIDCompanyDevice
1366:0105SEGGERJ-Link_J-Link V9.3 Plus
1366:0101SEGGERJ-Link ARM

At this point I've turned to disassembly. I've built myself an ELF file from the extracted firmware and the dumped RAM and I've loaded it into IDA. The J-Link is driven by a 1 byte command list:

File: command_list.txt
0x801173C byte_801173C  DCB 'I', 'D', 'S', 'E', 'G', 'G', 'E', 'R'
0x8011744 dword_8011744 DCD 0xB9FF7BBF       
0x8011748 usb_commands  DCD cmd_unsupported
0x801174C               DCD cmd_01_version
0x8011750               DCD cmd_02_reset_trst
0x8011754               DCD cmd_03_reset_target
0x8011758               DCD cmd_04_get_info
0x801175C               DCD cmd_05_set_speed
0x8011760               DCD cmd_06_update_firmware
0x8011764               DCD cmd_07_get_state
0x8011768               DCD cmd_08_set_ks_power
0x801176C               DCD cmd_09_register_unreg
0x8011770               DCD cmd_0a_indicators
0x8011774               DCD cmd_0b_permit
0x8011778               DCD cmd_0c_pcode
0x801177C               DCD cmd_0d_prot_version
0x8011780               DCD cmd_0e_set_emu_option
0x8011784               DCD cmd_unsupported
0x8011788               DCD cmd_unsupported
0x801178C               DCD cmd_11_merge_commands
0x8011790               DCD cmd_12_update_config_c000
0x8011794               DCD cmd_13_update_config_bf00
0x8011798               DCD cmd_unsupported
0x801179C               DCD cmd_15_spi
0x80117A0               DCD cmd_16_update_config_data
0x80117A4               DCD cmd_17_handle_c2
0x80117A8               DCD cmd_18_verify_signature
0x80117AC               DCD cmd_19
0x80117B0               DCD cmd_1a
0x80117B4               DCD cmd_unsupported
0x80117B8               DCD cmd_1c
0x80117BC               DCD cmd_unsupported
0x80117C0               DCD cmd_unsupported
0x80117C4               DCD cmd_unsupported
0x80117C8               DCD cmd_unsupported
0x80117CC               DCD cmd_unsupported
0x80117D0               DCD cmd_unsupported
0x80117D4               DCD cmd_c0_get_speeds
0x80117D8               DCD cmd_c1_get_hw_info
0x80117DC               DCD cmd_c2_get_counters
0x80117E0               DCD cmd_c3_test_net_speed
0x80117E4               DCD cmd_c4_cpu2_set_config
0x80117E8               DCD cmd_c5_cpu2_exec_cmd
0x80117EC               DCD cmd_c6_get_cpu2_caps
0x80117F0               DCD cmd_c7_select_if
0x80117F4               DCD cmd_c8_hw_clock
0x80117F8               DCD cmd_c9_hw_tms0
0x80117FC               DCD cmd_ca_hw_tms1
0x8011800               DCD cmd_cb_hw_data0
0x8011804               DCD cmd_cc_hw_data1
0x8011808               DCD cmd_cd_hw_jtag
0x801180C               DCD cmd_ce_hw_jtag2
0x8011810               DCD cmd_cf_hw_jtag3
0x8011814               DCD cmd_d0_hw_release_reset_stop_ex
0x8011818               DCD cmd_d1_hw_release_reset_stop_timed
0x801181C               DCD cmd_unsupported
0x8011820               DCD cmd_unsupported
0x8011824               DCD cmd_d4_get_max_mem_block
0x8011828               DCD cmd_d5_hw_jtag_write
0x801182C               DCD cmd_d6_hw_jtag_get_result
0x8011830               DCD cmd_unsupported
0x8011834               DCD cmd_unsupported
0x8011838               DCD cmd_unsupported
0x801183C               DCD cmd_da_hw_tck0
0x8011840               DCD cmd_db_hw_tck1
0x8011844               DCD cmd_dc_hw_reset0
0x8011848               DCD cmd_dd_hw_reset1
0x801184C               DCD cmd_de_hw_trst0
0x8011850               DCD cmd_df_hw_trst1
0x8011854               DCD cmd_e0_fine_write_read
0x8011858               DCD cmd_e1_cdc_exec
0x801185C               DCD cmd_unsupported
0x8011860               DCD cmd_unsupported
0x8011864               DCD cmd_unsupported
0x8011868               DCD cmd_e5_get_cpu2_caps_dll_version
0x801186C               DCD cmd_e6_read_config_bf00
0x8011870               DCD cmd_e7_sync_ks_power_from_config_data
0x8011874               DCD cmd_e8_get_caps
0x8011878               DCD cmd_e9_get_cpu_caps
0x801187C               DCD cmd_ea_exec_cpu_cmd
0x8011880               DCD cmd_eb_swo
0x8011884               DCD cmd_unsupported
0x8011888               DCD cmd_ed_get_caps_ex
0x801188C               DCD cmd_unsupported
0x8011890               DCD cmd_unsupported
0x8011894               DCD cmd_f0_get_hw_version
0x8011898               DCD cmd_f1_write_dcc
0x801189C               DCD cmd_f2_read_config_c000
0x80118A0               DCD cmd_f3_write_config_dummy
0x80118A4               DCD cmd_f4_write_mem
0x80118A8               DCD cmd_f5_read_mem
0x80118AC               DCD cmd_f6_measure_rtck_react
0x80118B0               DCD cmd_f7_write_mem_arm79
0x80118B4               DCD cmd_f8_read_mem_arm79
0x80118B8               DCD cmd_unsupported
0x80118BC               DCD cmd_fa_read_dcc
0x80118C0               DCD cmd_fb_write_dcc_ex
0x80118C4               DCD cmd_unsupported
0x80118C8               DCD cmd_unsupported
0x80118CC               DCD cmd_fe_read_emu_mem
0x80118D0               DCD cmd_unsupported

What I've discovered was that the user licenses (software licenses like to ones used by EMStudio) are stored in clear at address 0x0800c100, config licenses at 0x0800bf20, the serial number at 0x0800bf00 and there is one (256 byte) RSA digital signature at 0x0800b700. The signature is derived from the hardware ID of your microcontroller using 65537 as the public key and a 2048 bit modulus which is stored in the firmware. There is no way to calculate mathematically the digital signature without the private key which only SEGGER has. If SEGGER really wants to, it can always check this digital signature and detect a non genuine product. If this happens the only option is to patch the firmware (the code or the modulus). Fortunately, so far (up to software version V692), the only time the digital signature is used is when the licenses or serial number are updated.

The SEGGER software does some other checks to dissuade the use of clones:

Particularly the last "RDDI" check was introduced sometime is autumn of 2020 and the effect is that the software comes (a few seconds later) with a message saying that your probe is defective.

Analyzing the firmware further I have found a function (0xfe) which could be used to read any part of the probe memory (in 0x100 chuncks). When I've tried to use it all I was getting was timeout. Looking closer I've seen that a seed value was used and the function was working only when the seed was not zero. The seed is used to xor each returned word and then is advanced with another xor operation. To set this seed another (obscure) function must be used (0x0e) which sets various emu options and the subfunction 0x182 sets the value of this seed. All is left is to apply the xor in reverse to retrieve the dumped data.

I've written a utility usb_segger_fw_dump source code and linux executable which can retieve the memory content from any address. I've used this to dump the entire memory of J-Link V9, V10 and J-Link EDU Mini. I presume it is working with all of the J-Link probes.

Now I have to resist buying a (high speed USB) V10 which uses a LPC4322 CPU with a dual Cortex-M4/Cortex-M0 core.

This page does not contain any proprietary code. Don't ask me for firmware dumps because you won't get any. Here you can find all the tools to extract your own.

Tags: bootloader, firmware, j-link, segger.

Comments On This Entry

anotherandrew Submitted at 19:16:57 on 1 January 2021
Thank you for this interesting look under the hood of the Segger probes. It looks like the "set emu" subfunction 0x182 is not present on the V8 probes (I have a V8-EDU that fails with this software, but my V10 works). V8-EDU uses the AT91SAM7S64 which should be able to dump flash at 0x00100000, but fails at the "set seed" function.
Emil Submitted at 04:38:55 on 2 January 2021
You are right, the V8 doesn't support the firmware dump. I didn't look closely at V8 because its support is very limited and I am not using it anymore.

Apparently it works with V11 too: electronix.ru forum
ThaDr Submitted at 09:06:01 on 12 January 2021
Great article!! Source and executable links at the bottom aren't working unfortunately. I'd be very interested to have a look at them.
Emil Submitted at 17:18:40 on 12 January 2021
Links work fine. It's a problem on your side.
Franck Submitted at 10:33:03 on 28 January 2021
Newer versions of libjlinkarm.so don't provide the _init symbol so dump_segger_fw doesn't work.
Emil Submitted at 15:40:19 on 28 January 2021
After Rolf Segger reading my article and commenting on Hackaday you should expect some countermeasures. I don't plan to keep up with the firmware extraction, I've achieved my goal of extracting the bootloader and these are not changed often (if at all). Just use V692 (the latest one I've checked it was working).

If someone wants a newer firmware there will always be ways to get it. It just won't be as easy as running dump_segger_fw.
Franck Submitted at 16:14:32 on 28 January 2021
No problem. I understand. I just wanted to let you know.
Thanks for your work.
Emil Submitted at 23:23:44 on 28 January 2021
Fixed now, I'm not relying on the _init symbol anymore.
Shahar Hadas Submitted at 14:33:04 on 29 January 2021
Hi,
Out of curiosity purchased the same as one of your clones (the V9.6 one - PCB (1) one)
Managed to connect the SWD interface, and was indeed locked... so I erased the chip and then I was able to re-program the clone.
I have the same issue right now (with no boot loader) - but the firmware itself does run (and the jlink clone is usable).
One interesting thing is that I can't seem to communicate with the STM32 on the clone via SWD interface any more.
It simply notify me there's no such chip (tried with Segger J-Link and ST-Link/V2)
So I'm blocked in trying to re-program the clone in any way...
Do you have any idea as to why?
Emil Submitted at 19:39:56 on 29 January 2021
The SwD interface is always enabled but the reset line is not available on the clone connector. Try to solder a small wire on CPU pin 7 and connect it to your STLinkV2.
Shahar Hadas Submitted at 13:50:57 on 30 January 2021
That was my assumption ... but instead of soldering I ordered some micro IC clamps from AliExpress (your blog doesn't allow links) and waiting for them to arrive.

But to fully understand my situation, if I wanted to recover the boot loader for the clone, I need to order another clone and dump its bootloader using the J-Link-Dump-Bootloader ?
Emil Submitted at 17:14:40 on 30 January 2021
There is no clamp capable of 0.5 mm pitch. Your only option is to solder one wire on pin 7. Also you can use your probe with only the main firmware and no bootloader. My program ' 'dump_segger_fw' does this automatically if it cannot find a pre-saved bootloader. The drawback is that the probe won't update automatically.
Shahar Hadas Submitted at 21:06:54 on 14 February 2021
I can't paste links here, but look for 4000307558588 on AliExpress. This is what I ordered (package seems to taking its time...)

According to the photos and the reviews, seems to be able to work with the 0.5mm - or I actually wasted my money?
Emil Submitted at 00:28:39 on 15 February 2021
The pitch is 0.5mm but the pin width is 0.22mm. Good luck fitting your probe clamps through a 0.28mm space without touching the neighboring pins.

My advice is (if you don't want to destroy your ARM chip) to use magnet wire and a soldering iron. It's just one pin, it can't be that hard to solder even for a beginner.
Bulba Submitted at 19:42:38 on 28 February 2021
Thank you for this article. I have a question about calculating the firmware checksum. How is it implemented? Which firmware blocks are included in the calculation?
Emil Submitted at 22:05:32 on 28 February 2021
It is CRC16 with 0x8408 generator polynom calculated over the entire firmware including the gap at the end. For Jlink V9 it covers 0x2fffe in length.
Bulba Submitted at 11:13:48 on 1 March 2021
Thank you for your answer. I found firmware for v9 on the internet. I don't know what I'm doing wrong. I'm using HxD hex editor. After selecting the block from the address 0x08010000 with the length 0x2fffe, HxD calculates CRC-16 equal to 72e9. Firmware at the address 0x0803fffe contains the value e445. Can you help me, because I understand that saving FW with wrong checksum will damage j-link?
Emil Submitted at 16:44:02 on 1 March 2021
The CRC only affects the firmware, it won't "damage" anything while the bootloader is still there. For the CRC calculation see the source of my dump_segger_fw program.
Shahar Hadas Submitted at 22:24:13 on 9 March 2021
So ... got another "2nd clone". downloaded the bootloader.bin ... and burned it on the "1st clone".

Opened JLink config ... it auto-detected it needs a firmware - and just flashed the latest.

Interesting part was the issue wasn't the NRST pin after all, didn't tried it until I got the 2nd clone - but I was using ST-Link / Segger J-Link EDU - with 4Khz for SWD (like I did in the initial erase ...). And that was the issue. once I used 2000Hz - everything worked!

So now I ended up with 2 clones, 2 Segger EDUs and 3 ST-Link V2 - way more than I need :)
Mike Submitted at 16:37:50 on 22 March 2021
Do you have J-link V10 schematic?
Shahar Hadas Submitted at 20:20:44 on 17 April 2021
Trying to figure out the serial number.
On the "clone" I erased it's flash completely I now have a serial number of "-1".

I was wondering what are my options here in setting a non-blocked serial number.
I thought about erasing it again, writing the serial number in the correct location in the flash and then putting the bootloader.bin again (which will lock the flash again I assume?)
Emil Submitted at 02:15:02 on 18 April 2021
Any number is good if it's not in that list but original numbers tend to incorporate the hardware version in the decimal serial number as described above.
Also the flash doesn't get locked automatically.
Bart Submitted at 11:31:47 on 13 February 2022
FYI I tried to dump the firmware on a V10. The functionality was disabled in newer FW versions. I was able to dump it using firmware from V6.30 (2018 Jan 29 15:41). Obviously the addresses are different.
Emil Submitted at 20:19:32 on 13 February 2022
From the probe you only need the bootloader and that never changes. The firmware can be extracted from the libjlinkarm with my 'dump_segger_fw' program. It's true that recent versions prevented firmware extraction from libjlinkarm but if you read above you can see that I've solved this problem with a few bytes patch (the example is for linux).
Toto Submitted at 09:33:41 on 17 February 2022
Great job, Emil!
I have an original EDU v9.4 and a chinese clone without bootloader.
Using your usb_segger_fw_dump I successfully dumped the EDU, extracted the bootloader only, removed the RSA key and flashed it to the clone. After that segger software successfully flashed the latest FW to the clone.

Then I started to play with the EDU to try to make it a PLUS.
Here is part of the original config (I masked the SN):
0000bf00: XXXX XXXX ba78 3466 ffff ffff ffff ffff .....x4f........
0000bf10: 5345 4747 4552 2d45 4455 00ff ffff ffff SEGGER-EDU......
0000bf20: 466c 6173 6842 5000 ffff ffff ffff ffff FlashBP.........
0000bf30: 4744 4200 ffff ffff ffff ffff ffff ffff GDB.............
0000bf40: ffff ffff ffff ffff ffff ffff ffff ffff ................

Replacing the string SEGGER-EDU with 0xFF, effectively disables the EDU nag screen on each connect. Great!
Next I tried to add more licenses e.g. JFlash.
It works with no problem on J-link SW < 7.00. It also works with >7.00, but it shows a warning dialog saying that the probe is probably a clone (which is not). When I remove the added license everything is back to normal. I also noticed that it things it is clone if I modify the just after the SN word at 0000bf04. This led me to think that it might be some checksum that the licenses are checked against. I tried different regions but could not make the CRC32 to match.

So how do you think we could add licenses to the EDU without getting the clone warning? Do you know all the config fields?
Emil Submitted at 17:43:30 on 18 February 2022
The licenses I am using are: "GDB" "RDI" "FlashBP" "FlashDL" "JFlash"

The entire area bf00-c000 is digitally signed and the signature is at b700-b800. You can fill that with FFs
Ralf Submitted at 21:41:18 on 19 November 2022
First of all: Amazing work, Emil!

Nevertheless I'm finding myself in the same situation like you were, having one V9 (semi-) bricked and the other one working flawlessly. So I tried dumping the working one, but I cannot manage. All I get is:

00000000 01 57 45 4f a4 f2 e0 ea 01 57 45 4f a4 f2 e0 ea |.WEO.....WEO....|
00000010 01 57 45 4f a4 f2 e0 ea 01 57 45 4f a4 f2 e0 ea |.WEO.....WEO....|
...
0003fff0 01 57 45 4f a4 f2 e0 ea 01 57 45 4f a4 f2 e0 ea |.WEO.....WEO....|

Looking into your handy little tool it looked pretty much like the seed that you've been choosing and I got suspicious. Looking at the USB transfers with Wireshark I can see that the bulk-transfers sent by the JLink are filled with zeroes completely when trying to dump the firmware. Of course after "deciphering" it looks like the dump above. All other bulk-tranksfers like firmware version or licenses are working perfectly fine. Reading the comments I thought that just my firmware was too new already, so I downloaded an old version V6.30 (and a few more between 5.00 and 7.82) from the original website, but the probe behaves exactly like before no matter what firmware from their website I had flashed before. Fiddling around with your tool, changing or not even setting the seed value at all didn't change anything, eventhough not setting the seed should have resulted in timeouts as you said. It did not. Trying to rule out my host: I was trying different kernel versions betwenn 4.4.x and 6.0.x, various distributions/releases, as well as 64 and 32bit x86 architectures. Still always the same result.

Now I'm running out of ideas. I'm assuming that nowadays even "old" firmware versions maybe have been revised silently and don't allow creating a dump anymore.
Emil Submitted at 19:28:01 on 29 November 2022
First I've just tried 'usb_segger_fw_dump' on my up-to-date JLinkV9-782d and it works just fine, it dumps all its memory.

Secondly you don't need to dump anything to have a functional V9 probe. The firmware (all the ones that are not plain in the Firmwares directory) are in the libjlinkarm.so.7.82.4 file and you don't need the bootloader to use your probe. Patch the .so file as described above, then use 'dump_segger_fw -9' to create your firmware image. This will work even without a bootloader. The only drawback is that when a new firwmare is available you'll be nagged and you'll have to program it manually again (or you can set a date in the future if you don't want to update). The firmware in V9 hasn't been updated since May 2021 anyways.
Ralf Submitted at 10:34:15 on 6 December 2022
Thanks for your answer, Emil!
You are absolutely right with what you wrote. That's the way to revive an empty V9, especially as there don't seem to be any further firmwares coming up.

Nevertheless the cheap Chinese knock-off sparked my interest as it acted so weirdly. First of all: No, Segger did not patch the old firmware versions. By chance I found an old download on my NAS and it was still exactly the same binary that I can download today.

So why wasn't I able to dump the flash, not matter how old or new the running firmware was? It always did exactly the same, eventhough I could see the firmware's timestamp change. So I decided to use your cdc-acm firmware for dumping the flash by overlaying the lib, it flashed without any problems and even the new timestamp "22.2.2222" was visible...but no acm-device came up. Funnily it was still working as a JLink-device like it did before despite having a completely different firmware (without any JLink-stuff) now. Connecting to the device using openocd and reading the IDR gave me the correct APID, yet the mcu idcode didn't match. (More specificly: one bit didn't match.) After patching openocd to accept specifically this idcode as well, and a cortex m4 was successfully detected. Yay! Wait...M4? Poking around a bit I got access to the sram, but no chance to access the flash or even just to unlock/erase the mcu. Okay...one last idea: Maybe the mcu has a dfu bootloader in rom...it says it's an M4, right? So I pulled up boot0, plugged usb in and it identifies as "Nationstech DFU" (0x19f5:0x4537). Checking their website nationstech.com revealed that indeed they're only selling "N32F0x" and "4x" knock-offs, which is pretty consistent with what I found out before. At this time I simply stopped as all datasheets were in chinese and I was too lazy putting them in a translator.

My assumption is, that this device is running a custom firmware. When reading or writing the required flash sections using the dedicated commands, it acts accordingly. Even when "entering the bootloader" (who knows what it really does?) and flashing a new firmware, it only seems to pick very little and very specific information from that new image and stores it in flash (like the firmware timestamp), yet the manufacturer's firmware stays in place and keeps working as before.

Sorry for this long comment, but this whole thing is kinda crazy. I mean having a knock-off mcu on the board is pretty common nowadays, but putting an mcu with a different core and firmware mimicking the original in a way that (now) incompatible operations are just emulated dummies got me stunned.

Nevertheless: Thanks for your help and happy debugging everybody!
Emil Submitted at 18:24:01 on 7 December 2022
Were you surprised that a clone with a different micro-controller than the original doesn't behave the same way when running the official firmware?
The IC shortage seems to have bite even the clone makers ;-)
Ralf Submitted at 08:40:12 on 8 December 2022
Well, the MCU is labelled as an original stm32f2x, so I was assuming that they've instead been putting a fake copy of _that_ mcu at least. Turns out I'm pretty naive. ;-)
jefflynn Submitted at 17:33:03 on 14 November 2023
Hi, thanks for your work, I was able to recover two bricked jlinks using this information, but I have a weird problem. When I turn on the vcom port, the debugger dies. From that point on when I connect to USB, the virtual com port comes on, but it cannot work as a debugger. It is used to work before they got bricked, I clearly remember that. Any help appreciated.
Fang Submitted at 02:02:59 on 1 January 2024
I wonder if J-Link /Hardware ver 9.60 / clone firmware can be updated automatically? Thank you.
Emil Submitted at 16:08:59 on 19 January 2024
Latest firmware for Jlink V9 is dated "May 7 2021" and I doubt it will be updated again. With so many V9 clones I think Segger has dropped support for V9
Cyberschlumpf Submitted at 20:50:35 on 25 January 2024
I'd like to try to dump the whole firmware including bootloader on my EDU Mini with your tool. The dump is successfull but looks broken. As it's written in the commands, the feature has probably been disabled in the current version. I then downgraded the FW to v6.30 as Bart has written above. Running your tool just prints "xchg error" a 100 times and the dump is empty. Also tried with v6.30k which has the same release date as Bart's. Same effect. Which FW version can I use to dump the bootloader on my EDU Mini v1? Thanks
Cyberschlumpf Submitted at 07:56:32 on 26 January 2024
Need to correct myself after further tests: The dump with the current JLink FW versions looks like Ralf described it. All empty. But my EDU mini is a legit one of course. Also tried with the version you mentioned JLinkV9-782d - same effect.
Cyberschlumpf Submitted at 09:18:09 on 26 January 2024
Trying to dump the FW with dump_segger_fw also doesn't look right for the EDU Mini v1.: There are no strings in it apart from the header version and the entropy is still very high (> 7.8) Also it doesn't properly disassemble in IDA. In contrast the V9 works fine. What I noticed is that while listing it gives lots of entries with 0x00000->0x00000.. Is this correct?
Emil Submitted at 15:59:23 on 26 January 2024
I've just installed the latest JLink V794g, patched the lib as described above and then dumped all firmwares (105 of them) just fine.
49 of those are in clear in the Firmwares directory (not embedded in libjlinkarm.so anymore) including your JLinkEDUMini_V1.bin
It is possible that the ones stored in clear have some kind of scrambling/compression which is handled by the bootloader;
I haven't inverstigated any of that. I've only disassembled the V9 probe and that firmware had no strings beside the date and copyright.
I've sent the full dump of my EDUMini v1 to you via mail if you need to restore yours.
Cyberschlumpf Submitted at 17:27:10 on 27 January 2024
I noticed that many of the FW files seem to be externalized now. Pretty sure the external firmwares are also compressed/scrambled in addition, judging by the high entropy. Also in a "struct fw_entry" there now seem to be 3 more QWORDS per entry? Strange that I could not fully dump the whole firmware (including bootloader) neither from my EDU Mini v1 nor the various OB JLinks from my Nordic boards. I always only get 0x0000 payload...

Add A Comment

Your Name
Your EMail
Your Comment

Your submission will be ignored if any field is left blank or if you include clickable links (URLs without the "http://" start are fine). English only please. Your email address will not be displayed.