When using the ST-LINK Utility, it doesn't connect to the Discovery card.

[Dan in WY]

I'm using True Studio to compile a sample PWM program and using ST-LINK to program the device. It worked for the first 20 or so iterations but now it won't connect. It gives me this message:

OK I go to settings and there is no where to select "Connect Under Reset" nor is there anywhere to select a lower SWD Frequency. I had changed the ABH prescaler in clock configuration of MXCube from /1 to /16 going by the PWM example I found, but when I tried to change it to / 64 it quit working.

[Dan in WY]

I guess I wiped out the on-board ST-LINK since I was connected via the USB port. But I have a ST-LINK V2 programmer so I probably just need to connected it to the (4) SWD pins on the board.

[Dan in WY]

Assuming pin 1 of the SWD port is near the usb end of the card I connected according to the table 2 on page 24 of the manual:

1) VDD

2) SWCLK

3) GND

4) SWDIO

[Dan in WY]

Nope, that didn't work. I think there's a way to reflash it using the serial port...

[Dan in WY]

OK, you have to hold down the reset button for at least 1 second and then try to connect, then release the reset button.

[Tesla DeLorean]

So perhaps your code is reconfiguring the SWD/JTAG pins, or going into a low power mode. The other alternative is to strap BOOT0 HIGH, or select "Connect Under Reset" type options, which requires you also wire up NRST

[S.Ma]

Which STM32 part number and is it custom board ? If yes, which signals are connected between STM32 and STLinkV2?

[Dan in WY]

It's the STM32F100RB. I was using VCC (3v3), gnd, SWDIO and SWCLK. It works fine now connected to the USB port after I hit reset just after trying to connect with the ST-LINK utility. I had the same problem with an STM32F103C8T (Blue Pill) for a while and I'm wondering if it caused another problem I asked about in one of my other posts.

[Dan in WY]

https://community.st.com/s/feed/0D50X0000AhOHAY

I had a problem with the Blue Pill's outputs not working. The only pins that work are A0->A3, A9, A10 & B12.