abouts ST-link V2 VAPP

[miwa]

I would like to ask about the VAPP specifications.

Until now, the connection was made via JTAG as shown below.
There was no problem in writing.

1. VAPP
2. TMS_SWDIO
3. TCK_SWCLK
4. NRST
5. GND

Can I replace VAPP with VDD (pin 19) and feed power from ST-LINK?
If I do, should I short-circuit VDD and VAPP?

[raptorhal2]

Your connection is actually SWD.

VAPP is the MCU generated VDD to tell the ST-Link what signal level to use for the programming pins, it is not a supply to the MCU.

Similarly, GND is not sourced by the ST-Link.

[miwa]

If that is the case, do I need VAPP when wiring power from ST-LINK VDD?

[raptorhal2]

I haven't tried that. ST-LINK Pin 19 VDD is 3.3 V with no load, the User Manual says No Connection.

If Pin 19 has adequate power, the worst that can happen with no VAPP is  a failure to connect, in which case you can connect VAPP to VDD.

Note: other brand programmers may have Pin 19 connected to ground.