main.c

/*********************************************************************
*               (c) SEGGER Microcontroller GmbH & Co. KG             *
*                        The Embedded Experts                        *
*                           www.segger.com                           *
**********************************************************************

-------------------------- END-OF-HEADER -----------------------------

File    : Main.c
Purpose : Main application to demonstrate monitor mode debugging with J-Link,
          while keeping certain interrupts firing when main application is halted.
*/

#define MAIN_C

/*********************************************************************
*
*       Defines, fixed
*
**********************************************************************
*/

#define SYSTICK ((SYSTICK_REGS*)0xE000E010)
#define SCS     ((SCS_REGS*)0xE000ED00)

/*********************************************************************
*
*       Types, local
*
**********************************************************************
*/

typedef struct {
  volatile unsigned int CSR;
  volatile unsigned int RVR;
  volatile unsigned int CVR;
  volatile unsigned int CALIB;
} SYSTICK_REGS;

typedef struct {
  volatile unsigned int CPUID;       // CPUID Base Register
  volatile unsigned int ICSR;        // Interrupt Control and State Register
  volatile unsigned int VTOR;        // Vector Table Offset Register
  volatile unsigned int AIRCR;       // Application Interrupt and Reset Control Register
  volatile unsigned int SCR;         // System Control Register
  volatile unsigned int CCR;         // Configuration and Control Register
  volatile unsigned int SHPR1;       // System Handler Priority Register 1
  volatile unsigned int SHPR2;       // System Handler Priority Register 2
  volatile unsigned int SHPR3;       // System Handler Priority Register 3
  volatile unsigned int SHCSR;       // System Handler Control and State Register
  volatile unsigned int CFSR;        // Configurable Fault Status Register
  volatile unsigned int HFSR;        // HardFault Status Register
  volatile unsigned int DFSR;        // Debug Fault Status Register
  volatile unsigned int MMFAR;       // MemManage Fault Address Register
  volatile unsigned int BFAR;        // BusFault Address Register
  volatile unsigned int AFSR;        // Auxiliary Fault Status Register
  volatile unsigned int aDummy0[4];  // 0x40-0x4C Reserved
  volatile unsigned int aDummy1[4];  // 0x50-0x5C Reserved
  volatile unsigned int aDummy2[4];  // 0x60-0x6C Reserved
  volatile unsigned int aDummy3[4];  // 0x70-0x7C Reserved
  volatile unsigned int aDummy4[2];  // 0x80-0x87 - - - Reserved.
  volatile unsigned int CPACR;       // Coprocessor Access Control Register
} SCS_REGS;

/*********************************************************************
*
*       Global data
*
**********************************************************************
*/

volatile int MAIN_AppCnt;   // Incremented by user application
volatile int MAIN_TckCnt;   // Incremented by user application

/*********************************************************************
*
*       Global functions
*
**********************************************************************
*/

/*********************************************************************
*
*       SysTick_Handler()
*
*  Function description
*    Interrupt service routine called by SysTick interrupt.
*
*  Notes
*    (1) As it is configured in main() with a higher priority than the debug monitor, this routine cannot be debugged in monitor mode
*/
void SysTick_Handler(void);
void SysTick_Handler(void) {
  MAIN_TckCnt++;
}

/*********************************************************************
*
*       main
*/
void main(void) {
  unsigned int v;
  //
  // Increment MAIN_AppCnt while user application is running
  // Increment MAIN_MonCnt while application is halted and monitor is running
  // Always increment MAIN_TckCnt (no matter if in monitor or not)
  //
  //
  // Configure SysTick and debug monitor interrupt priorities
  // Low value means high priority
  // A maximum of 8 priority bits and a minimum of 3 bits is implemented per interrupt.
  // How many bits are implemented depends on the actual CPU being used
  // If less than 8 bits are supported, the lower bits of the priority byte are RAZ.
  // In order to make sure that priority of monitor and SysTick always differ, please make sure that the difference is visible in the highest 3 bits
  //
  v = SCS->SHPR3;
  v |= (0xFF << 0);       // Set priority of debug monitor to lowest priority so all interrupts keep firing while application is halted
  v &= ~(0xFFuL << 24);   // Highest prio for SysTick
//  v |= (0x80uL << 24);    // Set higher priority for SysTick than for debug monitor
  SCS->SHPR3 = v;
  //
  // Configure SysTick interrupt
  //
  SYSTICK->RVR = 0xFFFF;    // set reload
  SYSTICK->CVR = 0x00;      // set counter
  SYSTICK->CSR = 0x07;      // enable systick
  //
  // Main application
  //
  do {
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
    MAIN_AppCnt++;
  } while(1);
}