NRF52 – Not hitting breakpoints

[grindstaffp]

I have a project (c++) using the NRF52832 with BSP 14.2 under Visual Studio 2017 and VisualGDB 5.4 preview 3 (have tried under the latest 5.3 as well). I am attempting to interface with an I2C sensor and am having touble debugging within the library.

In the program main function, if I set a breakpoint before runtime on a function call to my sensor’s library, the program will bypass this breakpoint and continue to the main loop. Likewise, if a breakpoint is set on a library function call in the loop, the program runs without breaking. It is not until I remove and again place a breakpoint on the function call in the loop that the debugger hits the breakpoint. At this point I am able to step through the code as expected but not through the function I am aiming to step through.

Per other threads, I have compiler optimizations disabled and have –ggdb set. Being new to working on embedded devices at this level I am likely doing something wrong or misunderstand how this is supposed to work so any insight is appreciated. Attached is the GDBServer output as well as an image of my breakpoints.

 

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[support]

Hi,

Stepping through code on Nordic devices could be tricky due to the built-in watchdog that would reset the CPU each time it is stopped for a non-trivial amount of time, although it should not lead to the behavior you are describing.

From a quick look at the log file you attached, it looks that the Segger gdb stub fails to read the CPU registers shortly after the reset command:

Received monitor command: reset
Resetting target
Connected to 127.0.0.1
Read 2 bytes @ address 0x000003B4 (Data = 0xF107)
Read 2 bytes @ address 0x000003E2 (Data = 0x1D3B)
Read 4 bytes @ address 0x2000DFFC (Data = 0x4B642F0A)
Downloading 4 bytes @ address 0x2000DFFC
Reading all registers
ERROR: Can not read register 0 (R0) while CPU is running
ERROR: Can not read register 1 (R1) while CPU is running
ERROR: Can not read register 2 (R2) while CPU is running
ERROR: Can not read register 3 (R3) while CPU is running

This might affect the initial breakpoints or could cause other weird behavior.

Please try updating the Segger J-Link software and/or try adding delays (e.g. mon sleep 1000) before and after the reset command under VisualGDB Project Properties -> Debug Settings -> Advanced Settings.

[Author]

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