Ah right. I guess we need to look at the Blackpill circuit diagram and 411 datasheet to answer that one

Well done, thanks for that.
I'll compare that with the modified CAL file, not sure when I'll next get some time to do that. But at least you now have a functional work around.

Yes, but my version will let me know where it stops.
Can you run it and tell me what the LED does?
E.g. LED on, LED off. LED on permanently

I've modified your program a little to give us more information with the LED flash. Can you try this and let me know what the LED does? Please ensure you use the STARM_CAL_RTC.c from the "STM32F QUESTIONS" thread... https://www.flowcode.co.uk/forums/viewtopic.php?p=18918#p18918 Into direct...

No, I didn't change any settings.
Have you tried a power cycle of the board after the updated build is transferred?

If it still locks up, maybe my working version is due to some previously run code?
I think all the C code I've tried/run is posted on that previous post/thread

but it doesn't work unless I have to reload STARM_CAL_RTC.c

.. does this mean your Flowcode update reverts to the earlier original version?

Update... Ah, my previous post might not be true.. The Full Update doesn't seem to check all files. I'm running on the STARM_CAL_RTC.c from the "STM32F QUESTIONS" thread. Even if I delete it, Flowcode doesn't seem to detect this and update it, so I can't check what's in the Matrix repo. Be...

Hi, I just done a full update (V10), the CAL file is up to date, and includes the RTC enable code. I've successfully compiled your test program and it runs fine on my Blackpill, LED flash, no lockup and UART output OK. I also added a read and output of RTC seconds, which do increment. Hope that helps.

Matrix staff will no doubt sort it out.. probably next week
Meanwhile try the C file attached to Alan's post, to go into
C:\ProgramData\MatrixTSL\FlowcodeV11\CAL\STARM

It looks like the Matrix repo might be out of sync, my CAL file looks to be older.
See this post .. https://www.flowcode.co.uk/forums/viewt ... 794#p21794