For programming my STM32s, I’ve been using almost solely those 3-dollar USB dongles from China, which are basically ST-LINK/V2 clones. They do their basic task – programming and debugging STM32s – just fine. But they are missing two very handy features: 1. they do not have the SWO pins routed out (though it is possible to modify those dongles and replace one of the pins with the SWO) 2. they do not feature the VCP (Virtual Com Port), which basically enables your ST-Link to act as an USB-serial converter; ST introduced this on the ST-Link V2.1 (and then retrospectively on the V2A and B) 3. (also, the 2.1 has the MSD, or Mass Storage Device, functionality, which enables the ST-Link to act as an USB thumb drive and any bin files you copy into this “storage” get uploaded to any connected MCUs). Theoretically, I could modify the hardware of my existing dongles, but since it would involve a lot of tedious work and I needed to get more programmers, I decided to instead roll a batch of my own ST-Link V2.1s.