STLink V3 troubleshooting

[DOCon.1]

STM32CubeProgammer detects the ST link, and I successfully updated its firmware. But it doesn't detect the MCU. A StLinkV2 dongle on the same board works. I'm using the (SWDIO, SWCLK, RST pins). What troubleshooting steps would you take? Do you perhaps need more pins connected for V3? Thank you.

[Tesla DeLorean]

Connecting it to What?

Need a ground.

Perhaps back off the connection speed, the V3 runs up to 24 MHz, in my experience CM0(+) won't connect that fast. Try 1 MHz

[DOCon.1]

Thank you. I don't have those wired up - perhaps that would do it. Although it doesn't seem to be required for V2. I did try different speeds.

What about SWO? Is that also needed? Thank you.

[TDK]

Ground is always required. SWO is optional.

[Tesla DeLorean]

SWO can help in CM3, CM4, CM7 to provide a serial debug output, like a UART without using peripheral resources.