STLink and target Supply Power

[erussell]

I am working with a STM32L0538 discovery board and am ready to move to my own target board. According to the documentation I can use the STLink/V2-1 portion of the discovery board as the debugging interface for my target board using the CN5 connector. My question is: are there restrictions as to the supply power of my target board? I am planning to run the target on 2.8V, not 3.3V. Another question relates to the new STLink V3. The documentation says that for SWD the STLinkV3 is 3.3V compatible. Does this mean that the target board must run on 3.3V as well?

[Uwe Bonnes]

It seems the STLINKV3 has no level transaltion buffers and so V Target is expected to be 3.3V. If target is 3.3v tolerant, probably down to V Target = 2.5 Volt will work and V Target = 5 Volt is allowed as STLINKv3 pins a 5-Volt tolerant. So it depends if your target JTAG/SWD pins are 3.3 Volt tolerant.