I recently started studying STM32 microcontrollers (BluePill STM32F103 dev board + ST-link V2 clone). I was wondering if it is possible to add serial communication to ST-Link clone?

From what I understood, those clones are copied form ST-link schematic of official Nucleo boards. The ST-link on Nucleo boards is build with STM32F103CBT6 and pins 12 and 13 (PA_2 and PA_3) are used as TX and RX for serial communication with target microcontroller (and connects to PA_2 and PA_3 pins of targer). See page 65 of official Nucleo documentation

Meanwhile, on ST-link clones those pins are floating and not connected to anything

St-Link clone which I have

If I solder 2 wires to pins 12 and 13 of STM32 microcontroller on ST-link clone, would I be able to use those for serial communication with target microcontroller on BluePill board (PA_10 and PA_9 or PA_2 and PA_3)?


Looks like specifically this ST-link clone is made based on schematics of ST-link on old Discovery boards like this: ST-Link on Discovery boards In this "configuration" in can't be converted into ST-Link with Serial port feature, since this feature (as Virtual Com port) was added in ST-Link V2.1 on Nucleo boards and has another schematic: enter image description here

  • \$\begingroup\$ What this link is used for? In any case. these "clones" are not necessarily having the same firmware as the original. So it might be the case that there is no support for it in the firmware (whatever this support is for..). \$\endgroup\$ – Eugene Sh. Feb 27 at 20:13
  • \$\begingroup\$ ST-link is programming/debugging tool for STM32 microcontrollers. And they are compatible with official firmware for original ST-Link from STMicroelectronics. \$\endgroup\$ – Yehor Feb 27 at 20:21
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    \$\begingroup\$ @YehorPererva I know what ST-Link is. But I don't think the serial TX/RX are playing any role in programming. \$\endgroup\$ – Eugene Sh. Feb 27 at 20:22
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    \$\begingroup\$ electronics.stackexchange.com/a/321455/64158 says no, ST Link v2 doesn't have a USB-UART port \$\endgroup\$ – Marcus Müller Feb 27 at 20:23
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    \$\begingroup\$ @YehorPererva - no, that pin merely control the USB enumeration resistor to let the upgrade bootloader etc work (vs tying it permanently). It is not a mode pin for the STLINK firmware to have or not have the VCP port. That is rather determined by the firmware variant loaded. \$\endgroup\$ – Chris Stratton Feb 27 at 22:18

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