I know the crystal is enormous but I quite like the look of it there. The connector and the processor are taken straight off the discovery board as is the crystal. It is easily populated with 0805 size components. Once assembled I don’t much care what it says. I left the silkscreen too small but that is OK. I sent the board files off to Seeed Studios and waited – impatiently – over Christmas for the boards to arrive. There would be no extra bells and whistles – just a simple SWD programmer/debugger. It must replicate the functionality of the original ST-LINK/V2, take power from the USB connection and provide the three programming connections that I needed. I wanted something as small as I could manage but still reasonably easy to build. It didn’t take long to extract the relevant circuit details from the discovery documents and turn that into a small PCB. After that I would still have a full discovery board and a spare prototyping board. It would be easy to extract the processor from ST-LINK portion of the discovery board. And it comes with a handy prototyping board.Ī blank chip from the same source would be £4. The cheapest of them seemed to be the STM32F0Discovery – available at Farnell for about £8. They are cheap and the processor on them is already full of the right code. Then it occurred to me that there is a ST-LINK/V2 on all the recent crop of ST Discovery boards. But I didn’t want to faff about extracting firmware and programming up bare devices or putting ST code to dodgy use. With that in mind, I decided to build my own SWD-only programmer based on the ST-LINK/V2. That meant that I could get away with just three wires going to my target board so long as I was confident that the programmer and target voltages were the same.Įlsewhere, there is information on how to extract the ST-LINK/V2 firmware from the upgrade package and program your own device. The VCC line seems only to be needed to power level converters in the ST-LINK/V2. I have more details in this previous post. They supply SWDIO, SWDCK, GND and VCC for use with SWD programming and debugging.

I had previously determined that I needed only four wires from this to my target board. I didn’t really need all that functionality and, while not very big, it was clumsy to carry about. It is not too expensive ( about £22 from Farnell). This is a handy little device that can do a lot of jobs. One of the most commonly available and widely supported commercial programmers is the ST-LINK/V2. One minor annoyance is the question of a programmer. They are easy to use, powerful and cheap and there are lots of options for developing code. I enjoy working with the STM32 processors.

St link v2 driver download