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My original ST-LINK/V2 has been broken. There was the Short circuit between VDD and GND pins. I changed the MCU(STM32F103C8T6) and the voltage regulator(LD3985M33R) with new ones. Short Circuit problem gone, but when I plugged ST-LINK to USB port, the indicator LED is on very lightly. USB Device not recognized window shown at PC screen. I measured VDD pin as 3.29V. Power is OK. ST-LINK/V2 is not open source and I couldnt reach its schematic. What should I do to fix the issue? Thanks your helps...

enter image description here

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    \$\begingroup\$ Did you reprogram the firmware to the MCU? These are also very cheap items, are you sure buying components and putting time to repair it is worth it? \$\endgroup\$
    – Justme
    Commented Jan 21, 2020 at 6:50
  • \$\begingroup\$ You can buy a replacement ST Link V2 on ebay for about £4/$5 including shipping. That's cheaper than buying the STM32F103C8T6 on its own! \$\endgroup\$
    – ChrisD91
    Commented Jan 21, 2020 at 9:49
  • \$\begingroup\$ Hi Justme & Chistopher, I couldn't reprogram the MCU because of not recognising from USB port. Maybe there is another way to flash firmware to the MCU. I have already had the MCU and the regulator. So I want to repair my st-link as it is possible. \$\endgroup\$
    – OzkulA
    Commented Jan 22, 2020 at 6:09

3 Answers 3

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You need to upload ST Link firmware onto the MCU. It might be possible with some soldering/desoldering involved.

I am not sure if the original firmware is available freely, but there is STSW-LINK007 firmware update package on ST site and I suspect it contains entire firmware ready to upload.

The first problem is that the MCU must be in DFU mode for this. It is done by selecting system memory boot mode (boot0 = 1, boot1 = 0). So, you have to find a way to temporarily connect boot0 pin to VCC and then power reset. Preferably without making another short on board.

The second problem is that STSW-LINK007 requires USB DFU bootloader, and there is a chance the one installed on your MCU uses UART protocol. See AN2606 for details. If this is the case you'd have to connect USB-Serial adapter board to UART port pins and install USB bootloader first, then try firmware update again.

But frankly, I agree with the comments left on your question - unless you are doing this for fun and education, it is not worth the time spent.

Finally, it might be a bad photo angle, but it seems you have a lot of bridging on the MCU chip. You might want to check that out first.

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  • \$\begingroup\$ Hi Maple, thank you for your information and help. You are right. It doesnt seem worth the effort but I want to try if there is any solution of it. As you said, I try to find USB bootloader and flash it to the MCU via UART while the MCU is in DFU mode. Then, try to flash the firmware with STlink Utility. Thanx. \$\endgroup\$
    – OzkulA
    Commented Jan 22, 2020 at 6:44
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Considering that you changed the MCU with an empty part and the original MCU contains the software required for that whole thing it's now probably finally gone. You'll need to get a new one.

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At last, I solved the issue in the help of Maple's advises. The steps I followed below:

  • Pull the BOOT0 pin up to VDD in order to flash bootloader firmware (R1 desoldered and connected the BOOT0 side of R1 to VDD).
  • Soldered CN1 headers and connected the SWDIO,SWCLK,GND and VDD pins.

image

  • Flashed the STLinkV2.J16.S4.hex file with another ST-Link programmer.(while flashing the firmware, the st-link should powered on by USB. )
  • Resoldered R1. Now it is ready.:)

  • Update the firmware with STLink Utility to latest version.

thanks to everyone who left a comment..

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  • \$\begingroup\$ Did you check what the other 2 pins of CN1 are? Can R1 be just a pull-down and one of the CN1 pins is connected to BOOT0 to provide VDD? Then no soldering might be necessary. \$\endgroup\$ Commented Jan 23, 2020 at 13:14
  • \$\begingroup\$ @thebusybee, I checked them, but there are not connection with MCU's pins directly or indirectly. \$\endgroup\$
    – OzkulA
    Commented Jan 27, 2020 at 5:37

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