Giga M1 + ST-Link v3. Always have to use BOOT0

[cbroadbo]

I have an Arduino Giga R1 that functions fine. I can run various sketches on it via USB with no issues.

But I want to get my ST-Link V3 connected to it and use it for debugging. I am able to do so with one of the cables. It has a connector that is too long but all the pins line at the one end line up correctly. However, the only way I can get a connection to it is to restart the Giga by unplugging from USB and then plug in while holding down the BOOT0 button. Once I do that, I can connect to it and debug just fine with Arduino IDE. I'm also able to use the same process to connect to it with STM32CubeProgrammer. Once connected with STM32CubeProgrammer, I can erase the whole chip or change the option bytes, and flash images, refresh the Arduino Bootloader, etc.

I'm hoping that someone can tell me what I may need to change so that I can connect to it without having to restart it each time while holding the BOOT0 button.

I have many STM32 boards(nucleos, discos, etc.) and never have to resort to using BOOT0 with any of those during normal programming activity.

Any thoughts?

Thanks,
Craig

[cbroadbo]

A general issue that can cause this issue of not being able to connect to the MCU with the programmer is not having the programming lines/pins(JTAG or SWD) configured in your firmware. That likely leaves them floating which is a problem. I've run into this from time to time on other boards. That's easy, just configure them. However, the STM32H747 being dual core MCU seems to have some other things going on.