This document provide steps required to manually trigger an exception in Mbed-OS and see the exception working and steps to analyze the crash dump.
From the command-line, import the example:
mbed import mbed-os-example-fault-handler
cd mbed-os-example-fault-handler
Invoke mbed compile, and specify the name of your platform and your favorite toolchain (GCC_ARM, ARM, IAR). For example, for the ARM Compiler 5:
mbed compile -m K64F -t ARM
Your PC may take a few minutes to compile your code. At the end, you see the following result:
[snip]
+----------------------------+-------+-------+------+
| Module | .text | .data | .bss |
+----------------------------+-------+-------+------+
| Misc | 13939 | 24 | 1372 |
| core/hal | 16993 | 96 | 296 |
| core/rtos | 7384 | 92 | 4204 |
| features/FEATURE_IPV4 | 80 | 0 | 176 |
| frameworks/greentea-client | 1830 | 60 | 44 |
| frameworks/utest | 2392 | 512 | 292 |
| Subtotals | 42618 | 784 | 6384 |
+----------------------------+-------+-------+------+
Allocated Heap: unknown
Allocated Stack: unknown
Total Static RAM memory (data + bss): 7168 bytes
Total RAM memory (data + bss + heap + stack): 7168 bytes
Total Flash memory (text + data + misc): 43402 bytes
Image: .\.build\K64F\ARM\mbed-os-example-fault-handler.bin
- Connect your mbed device to the computer over USB.
- Copy the binary file(mbed-os-example-fault-handler.bin) to the mbed device.
- Press the reset button to start the program.
An exception will be triggered and you will see following crash information in STDOUT. The crash information contains register context at the time exception and current threads in the system. The information printed out to STDOUT will be similar to below. Registers captured depends on specific Cortex-M core you are using. For example, if your target is using Cortex-M0, some registers like MMFSR, BFSR, UFSR may not be available and will not appear in the crash log.
Mbed-OS exception handler test
Forcing exception: 3
++ MbedOS Fault Handler ++
FaultType: HardFault
Context:
R0 : 0000AAA3
R1 : 00000208
R2 : 00004B8C
R3 : 00004D69
R4 : 20000840
R5 : 00000003
R6 : 00000000
R7 : 00000000
R8 : 00000000
R9 : 00000000
R10 : 00000000
R11 : 00000000
R12 : 000084A9
SP : 20001F10
LR : 00002C59
PC : 00004B4E
xPSR : 81000000
PSP : 20001EA8
MSP : 2002FFD8
CPUID: 410FC241
HFSR : 40000000
MMFSR: 00000000
BFSR : 00000000
UFSR : 00000100
DFSR : 00000008
AFSR : 00000000
Mode : Thread
Priv : Privileged
Stack: PSP
-- MbedOS Fault Handler --
++ MbedOS Error Info ++
Error Status: 0x80FF013D Code: 317 Module: 255
Error Message: Fault exception
Location: 0x5DEB
Error Value: 0x4B4E
Current Thread: main Id: 0x20001F28 Entry: 0x6321 StackSize: 0x1000 StackMem: 0x20000F28 SP: 0x2002FF70
For more info, visit: https://armmbed.github.io/mbedos-error/?error=0x80FF013D
-- MbedOS Error Info -
== The system has been rebooted due to a fatal error. ==
Rebooted and Halted...test completed
To investigate more on this hardfault copy and save this crash information to a text file and run the crash_log_parser.py tool as below.
crash_log_parser.py <Path to Elf/Axf file of the build> For example: crashlogparser.py crash.log C:\MyProject\BUILD\k64f\arm\mbed-os-hf-handler.elf C:\MyProject\BUILD\k64f\arm\mbed-os-hf-handler.map
An example output from running crash_log_parser is shown below.
Parsed Crash Info:
Crash location = zero_div_test() [0000693E]
Caller location = $Super$$main [00009E99]
Stack Pointer at the time of crash = [20001CC0]
Target/Fault Info:
Processor Arch: ARM-V7M or above
Processor Variant: C24
Forced exception, a fault with configurable priority has been escalated to HardFault
Divide by zero error has occurred
Done parsing...
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