Robotdyn STM32 Black Pill not recognised when connected to ST-Link v2 (SOLVED)

[JustinSB]

I have 4 STM32 boards. Two very cheap Blue Pill boards (from two different suppliers), and two RobotDyn Black Pill boards (from another two completely different suppliers). I also have two ST-Link v2 clone type USB adapters - one with the original firmware that it shipped with (V2.J24.S4) and one that was updated to the latest ST firmware (V2.J33.S7) using the ST Utility. When I plug either of my Blue Pill boards into either of the ST-Links, the ST Utility can "see" them and I can use my Arduino IDE to program them. However, when I plug either of my RobotDyn Black Pill boards into either one of the ST-Link adapters, neither the ST-Link Utility nor the Arduino IDE can recognise them. the ST-Link Utility says that it cannot connect to target and the Arduino IDE says "No target connected". I'm sure that I'm missing something silly or blindingly obvious here, but I just can't work out what. The Robotdyn boards are supposed to be far better built than the standard Blue Pill boards, but it's the Black Pill boards that I can't get working, & the Blue Pill boards worked straight away. What am I doing wrong please?

[MikeDB]

I only use Blue Pills but my guessese are

1. Is the Black Pills may have different bootloaders loaded that expect you to load the program via a CH340 USB to USART1 convertor only ? Or something along those lines ?
2. Are you providing 3.3v to the Black Pill ? It doesn't accept 5V at all
3. Some Black Pills don't even come with a bootloader and you need to burn it first - see https://wiki.stm32duino.com/index.php?title=Burning_the_bootloader#Flashing_the_bootloader_onto_the_Black_Pill_via_UART_using_a_Windows_machine
4. You have a Black Pill with the GD32F103 clone. If so best bet is to put it in the bin :)

[JustinSB]

I'm using RobotDyn Black Pill STM32F103C8T6 boards.

I connect them only using the ST-Link, using 3.3v, GND, SWDIO & SWCLK pins (I never use 5v)

I will have a good look at that URL & see if that fixes me. Thanks.

[Tesla DeLorean]

If the ST-LINK can't connect it suggests issues with the power, the pins you're using or the device reconfiguring pins used for debugging.

You perhaps want to connect NRST so you can "connect under reset" from the tools.

Try pulling BOOT0 High so that the ROM runs, and not whatever is currently in FLASH.

Check the voltages, check the state of NRST normally.

[S.Ma]

https://www.stm32duino.com/viewtopic.php?t=2900

[JustinSB]

Thank you all for the info. I have now managed to resolve all of my problems. The Black Pill boards that I got appear to have come without bootloaders, whereas the one that my friend got in Japan (who I have been comparing things with, but didn't mention in my original post) came with a bootloader pre-loaded. I followed the info given by @MikeDB​, @Community member​ and @S.Ma​  above & flashed one of Roger Clark's bootloaders, after which I was able to get everything to work. The most important thing was to set my Boot0 jumper High in order to flash the bootloader. That was the gap in my knowledge. Thanks all, much appreciated.