SPRAD28 October   2022 AM2431 , AM2432 , AM2434 , AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , AM26C31 , AM26C31-EP , AM26C31C , AM26C31I , AM26C31M , AM26C32 , AM26C32-EP , AM26C32C , AM26C32M , AM26LS31 , AM26LS31M , AM26LS32A , AM26LS32AC , AM26LS32AM , AM26LS33A , AM26LS33A-SP , AM26LS33AM , AM26LV31 , AM26LV31E , AM26LV31E-EP , AM26LV32 , AM26LV32E , AM26LV32E-EP , AM26S10 , AM2732 , AM2732-Q1

 

  1.   Abstract
  2.   Trademarks
  3. 1 Building for Debug
    1. 1.1 Disable Code Optimization
    2. 1.2 Using the Debug SDK Libraries
  4. 2 Code Composer Studio Stop-Mode Debugging
    1. 2.1 Configuring the Debugger
    2. 2.2 Breakpoints and Watchpoints
      1. 2.2.1 Software Breakpoints
      2. 2.2.2 Hardware Breakpoints
      3. 2.2.3 Watchpoints
    3. 2.3 Inspecting Device Registers
    4. 2.4 Inspecting Disassembly
  5. 3 Debug Logging
    1. 3.1 Logging Methods
    2. 3.2 Log Zones
    3. 3.3 Asserts
    4. 3.4 Example Usage
  6. 4 Multi-Core Debug
    1. 4.1 Grouping Cores
      1. 4.1.1 Fixed Group
      2. 4.1.2 Hiding Cores
    2. 4.2 Using Multiple Workbench Windows
    3. 4.3 Global Breakpoints
  7. 5 Debugging Arm Cortex-R5 Exceptions
    1. 5.1 Exception Priority Order
    2. 5.2 Aborts
      1. 5.2.1 Data Aborts
        1. 5.2.1.1 Alignment
        2. 5.2.1.2 Background Aborts
        3. 5.2.1.3 Permission
        4. 5.2.1.4 Synchronous/Asynchronous External
        5. 5.2.1.5 Synchronous/Asynchronous ECC
      2. 5.2.2 Synchronous/Asynchronous Aborts
        1. 5.2.2.1 Changing an Asynchronous Abort to a Synchronous Abort
        2. 5.2.2.2 Synchronous Abort
        3. 5.2.2.3 Asynchronous Abort
        4. 5.2.2.4 Debugging Asynchronous Abort
      3. 5.2.3 Prefetch Abort
        1. 5.2.3.1 Possible Reasons for Prefetch Abort
        2. 5.2.3.2 Handling Prefetch Abort Exception
      4. 5.2.4 Undefined Instruction
        1. 5.2.4.1 Possible Reasons for Undefined Instruction Exception
        2. 5.2.4.2 Handling Undefined Instruction Exception
    3. 5.3 Fetching Core Registers Inside an Abort Handler
  8. 6 Debugging Arm Cortex-M4 Exceptions
    1. 6.1 Exception Entry and Exit Sequence
      1. 6.1.1 Entry Sequence
      2. 6.1.2 Exception Exit Sequence
      3. 6.1.3 Decoding EXC_RETURN Value
    2. 6.2 Faults Handling
      1. 6.2.1 There are 15 System Exceptions by Arm Cortex M Processors
        1. 6.2.1.1 Causes of Faults
      2. 6.2.2 HardFault Exception
        1. 6.2.2.1 Causes of HardFault Exception
      3. 6.2.3 Configurable Fault Exceptions
        1. 6.2.3.1 Mem Manage Fault Exception
        2. 6.2.3.2 BusFault Exception
        3. 6.2.3.3 Usage Fault Exception
      4. 6.2.4 Control Registers
        1. 6.2.4.1 SHP - System Handler Priority Register
      5. 6.2.5 Status Registers
        1. 6.2.5.1 Undefined Instruction Handling Example
        2. 6.2.5.2 Invalid State Handling Example
      6. 6.2.6 Printing the Stack Frame
  9. 7 Debugging Memory
    1. 7.1 Viewing Device Memory
    2. 7.2 Linker Command File (linker.cmd)
      1. 7.2.1 The Memory Directive
      2. 7.2.2 The Sections Directive
    3. 7.3 Stack Overflow
      1. 7.3.1 -fstack-protector
      2. 7.3.2 -fstack-protector-strong
      3. 7.3.3 -fstack-protector-all
      4. 7.3.4 Enabling Stack Smashing Detection
      5. 7.3.5 Enabling Stack Smashing Detection
    4. 7.4 Variables and Expressions View in CCS
    5. 7.5 Understanding Your Application's Memory Allocation
    6. 7.6 FreeRTOS ROV
  10. 8 Debugging Boot
    1. 8.1 ROM Boot
    2. 8.2 SBL Boot
    3. 8.3 GEL Files
      1. 8.3.1 Debugging Init Code
        1. 8.3.1.1 Disable Auto-Run to Main
  11. 9 Debugging Real-Time Control Loops
    1. 9.1 Trace
      1. 9.1.1 Processor / Core Trace
      2. 9.1.2 How to Use CCS to Capture Trace Data on an AM243x
    2. 9.2 Code Profile / Coverage
      1. 9.2.1 CCS Count Event
    3. 9.3 Real-Time UART Monitor
      1. 9.3.1 Confirm CCS Features
      2. 9.3.2 Create Target Configuration File
      3. 9.3.3 Add Serial Command Monitor Software
      4. 9.3.4 Launch Real Time Debug
  12. 10E2E Support Forums

6.2.5.2 Invalid State Handling Example

You can also simulate a different UsageFault exception of invalid state (UFSR = 0x2). This fault means that the processor has attempted to execute an instruction that makes illegal use of the Execution Program Status Register (EPSR).

When the INVSTATE bit of the UFSR is set, the PC value stacked for the exception return points to the instruction that attempted the illegal use of the EPSR. Potential reasons:

  • Loading a branch target address to PC with LSB=0
  • Stacked PSR corrupted during exception or interrupt handling
  • Vector table contains a vector address with LSB=0

The LSB of the address is loaded to the 'T' bit of the EPSR. If this bit is set, it means that the processor is in Thumb mode, if this bit is cleared, it means that the processor is in Arm mode. Since Arm Cortex M Series support only Thumb ISA, then this bit must be set during execution. This is something that is done by the compiler, but if you assign an address manually to the PC, then you need to take care of this bit by ourselves.

The code below causes the processor to halt in the UsageFault handler, but this time with UFSR = 0x2 (Invalid State):

void empty_main(void *args)
{
    /* Open drivers to open the UART driver for console */
    Drivers_open();
    Board_driversOpen();

    //Enable all configurable exceptions:

    uint32_t *pSHCSR = (uint32_t*)0xE000ED24;
    *pSHCSR |= ( 1<< 16); //Memory Manage Fault
    *pSHCSR |= ( 1<< 17); //Bus Fault
    *pSHCSR |= ( 1<< 18); //Usage Fault

    //Address LSB = 0
    uint32_t* pADDR = (uint32_t*)0x00030000;
    *pADDR = 0xFFFFFFFF;
    void (*temp_address) (void);
    temp_address = pADDR;
    temp_address();

    while(1);

    Board_driversClose();
    Drivers_close();
}
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