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

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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\$ @duskwuff - looks like it is not a case with my clone. And, I think other problem is that my clone is made with STM32F101, meanwhile ST-Link from Nucleo is made with STM32F103 \$\endgroup\$ – Yehor Feb 27 at 21:12
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    \$\begingroup\$ @YehorPererva Using a STM32F101 instead of a '103 is a common "hack" in cheap ST-Link devices. The silicon in the two parts is identical, and the USB transceiver usually works. \$\endgroup\$ – duskwuff Feb 27 at 21:13
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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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