I am new to MBED though I have used CMSIS-RTOS-RTX on a project back in the day when MBED was just getting started. I am using Mbed Studio v 1.0 downloaded in the last few days.
I have a new NRF51-DK board that I have updated the DAPLink firmware to version 0253 using the process described here, without apparent issue.
The MBED OS 5 version of the mbed-os-example-blinky program builds for without issue and I can download it to the target cpu on the NRF51-DK using the button (having the play icon) in Mbed Studio. This works fine and I can change the LED flash rate by setting BLINKING_RATE_MS to different values in main.cpp and seeing the results.
My problem arises when I try to debug the program (still in , obviously). The program builds and compiles OK and attaches to the debugger but I get the following error
05028:INFO:gdbserver:RTX5 loaded successfully
Attached to debugger on port 50000
0005170:WARNING:flash_builder:Chip erase used when flash address 0x1b000 is not the same as flash start 0x0
0007739:INFO:loader:Erased chip, programmed 67584 bytes (66 pages), skipped 0 bytes (0 pages) at 25.17 kB/s
Image loaded: c:\Users\Mike-remote\Mbed Programs\mbed-os-example-blinky-5-v2\BUILD\NRF51_DK\GCC_ARM\mbed-os-example-blinky-5-v2.elf
Note: automatically using hardware breakpoints for read-only addresses.
[New Thread 2]
[New Thread 536887008]
[New Thread 536886672]
[New Thread 536886940]
2 “Handler mode” received signal SIGSEGV, Segmentation fault.
[Switching to Thread 2]
0xfffffffe in ?? ()
Can anyone give me any ideas what is going wrong here and what I need to do to fix the problem ? The exact same .hex output file runs OK when I download it to the target by copying to the DAPLINK disk in Windows.