CMSIS-Core (Cortex-M): Startup File startup_<device>.c

| CMSIS-Core (Cortex-M) Version 5.4.0 CMSIS-Core support for Cortex-M processor-based devices

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Startup File startup_<device>.c

The Startup File startup_<device>.c contains:

- The reset handler which is executed after CPU reset and typically calls the SystemInit function.
- The setup values for the Main Stack Pointer (MSP).
- Exception vectors of the Cortex-M Processor with weak functions that implement default routines.
- Interrupt vectors that are device specific with weak functions that implement default routines.

The file exists for each supported toolchain and is the only tool-chain specific CMSIS file.

To adapt the file to a new device only the interrupt vector table needs to be extended with the device-specific interrupt handlers. The naming convention for the interrupt handler names are <interrupt_name>_IRQHandler. This table needs to be consistent with IRQn_Type that defines all the IRQ numbers for each interrupt.

Example:

The following example shows the extension of the interrupt vector table for the LPC1100 device family.

/*----------------------------------------------------------------------------
Exception / Interrupt Handler
*----------------------------------------------------------------------------*/
/* Exceptions */
void WAKEUP0_IRQHandler (void) __attribute__ ((weak, alias("Default_Handler")));
void WAKEUP1_IRQHandler (void) __attribute__ ((weak, alias("Default_Handler")));
void WAKEUP2_IRQHandler (void) __attribute__ ((weak, alias("Default_Handler")));
// :
// :
void EINT1_IRQHandler (void) __attribute__ ((weak, alias("Default_Handler")));
void EINT2_IRQHandler (void) __attribute__ ((weak, alias("Default_Handler")));
// :
// :
/*----------------------------------------------------------------------------
Exception / Interrupt Vector table
*----------------------------------------------------------------------------*/
extern const pFunc __VECTOR_TABLE[240];
const pFunc __VECTOR_TABLE[240] __VECTOR_TABLE_ATTRIBUTE = {
(pFunc)(&__INITIAL_SP), /* Initial Stack Pointer */
Reset_Handler, /* Reset Handler */
NMI_Handler, /* -14 NMI Handler */
HardFault_Handler, /* -13 Hard Fault Handler */
MemManage_Handler, /* -12 MPU Fault Handler */
BusFault_Handler, /* -11 Bus Fault Handler */
UsageFault_Handler, /* -10 Usage Fault Handler */
0, /* Reserved */
0, /* Reserved */
0, /* Reserved */
0, /* Reserved */
SVC_Handler, /* -5 SVCall Handler */
DebugMon_Handler, /* -4 Debug Monitor Handler */
0, /* Reserved */
PendSV_Handler, /* -2 PendSV Handler */
SysTick_Handler, /* -1 SysTick Handler */
/* Interrupts */
WAKEUP0_IRQHandler, /* 0 Wakeup PIO0.0 */
WAKEUP1_IRQHandler, /* 1 Wakeup PIO0.1 */
WAKEUP2_IRQHandler, /* 2 Wakeup PIO0.2 */
// :
// :
EINT1_IRQHandler, /* 30 PIO INT1 */
EINT2_IRQHandler, /* 31 PIO INT2 */
// :
// :
};

# startup_Device.c Template File

A compiler agnostic startup_Device.c Template File for an Armv7-M processor like Cortex-M3 is shown below. The C startup file relys on certain compiler specific preprocessor defines specified in CMSIS compiler headers:

- __INITIAL_SP
- __STACK_LIMIT
- __PROGRAM_START
- __VECTOR_TABLE
- __VECTOR_TABLE_ATTRIBUTE

    /******************************************************************************
     * @file     startup_Device.c
     * @brief    CMSIS-Core(M) Device Startup File for <Device>
     * @version  V2.0.0
     * @date     20. May 2019
     ******************************************************************************/
    /*
     * Copyright (c) 2009-2019 Arm Limited. All rights reserved.
     *
     * SPDX-License-Identifier: Apache-2.0
     *
     * Licensed under the Apache License, Version 2.0 (the License); you may
     * not use this file except in compliance with the License.
     * You may obtain a copy of the License at
     *
     * www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an AS IS BASIS, WITHOUT
     * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */

    #include "<Device>.h"

    /*----------------------------------------------------------------------------
      Exception / Interrupt Handler Function Prototype
     *----------------------------------------------------------------------------*/
    typedef void( *pFunc )( void );

    /*----------------------------------------------------------------------------
      External References
     *----------------------------------------------------------------------------*/
    extern uint32_t __INITIAL_SP;

    extern __NO_RETURN void __PROGRAM_START(void);

    /*----------------------------------------------------------------------------
      Internal References
     *----------------------------------------------------------------------------*/
    void __NO_RETURN Default_Handler(void);
    void __NO_RETURN Reset_Handler  (void);

    /*----------------------------------------------------------------------------
      Exception / Interrupt Handler
     *----------------------------------------------------------------------------*/
    /* Exceptions */
    void NMI_Handler            (void) __attribute__ ((weak, alias("Default_Handler")));
    void HardFault_Handler      (void) __attribute__ ((weak, alias("Default_Handler")));
    void MemManage_Handler      (void) __attribute__ ((weak, alias("Default_Handler")));
    void BusFault_Handler       (void) __attribute__ ((weak, alias("Default_Handler")));
    void UsageFault_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void SVC_Handler            (void) __attribute__ ((weak, alias("Default_Handler")));
    void DebugMon_Handler       (void) __attribute__ ((weak, alias("Default_Handler")));
    void PendSV_Handler         (void) __attribute__ ((weak, alias("Default_Handler")));
    void SysTick_Handler        (void) __attribute__ ((weak, alias("Default_Handler")));

    void Interrupt0_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt1_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt2_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt3_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt4_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt5_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt6_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt7_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt8_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));
    void Interrupt9_Handler     (void) __attribute__ ((weak, alias("Default_Handler")));

    /*----------------------------------------------------------------------------
      Exception / Interrupt Vector table
     *----------------------------------------------------------------------------*/
    extern const pFunc __VECTOR_TABLE[240];
           const pFunc __VECTOR_TABLE[240] __VECTOR_TABLE_ATTRIBUTE = {
      (pFunc)(&__INITIAL_SP),                   /*     Initial Stack Pointer */
      Reset_Handler,                            /*     Reset Handler */
      NMI_Handler,                              /* -14 NMI Handler */
      HardFault_Handler,                        /* -13 Hard Fault Handler */
      MemManage_Handler,                        /* -12 MPU Fault Handler */
      BusFault_Handler,                         /* -11 Bus Fault Handler */
      UsageFault_Handler,                       /* -10 Usage Fault Handler */
      0,                                        /*     Reserved */
      0,                                        /*     Reserved */
      0,                                        /*     Reserved */
      0,                                        /*     Reserved */
      SVC_Handler,                              /*  -5 SVCall Handler */
      DebugMon_Handler,                         /*  -4 Debug Monitor Handler */
      0,                                        /*     Reserved */
      PendSV_Handler,                           /*  -2 PendSV Handler */
      SysTick_Handler,                          /*  -1 SysTick Handler */

      /* Interrupts */
      Interrupt0_Handler,                       /*   0 Interrupt 0 */
      Interrupt1_Handler,                       /*   1 Interrupt 1 */
      Interrupt2_Handler,                       /*   2 Interrupt 2 */
      Interrupt3_Handler,                       /*   3 Interrupt 3 */
      Interrupt4_Handler,                       /*   4 Interrupt 4 */
      Interrupt5_Handler,                       /*   5 Interrupt 5 */
      Interrupt6_Handler,                       /*   6 Interrupt 6 */
      Interrupt7_Handler,                       /*   7 Interrupt 7 */
      Interrupt8_Handler,                       /*   8 Interrupt 8 */
      Interrupt9_Handler                        /*   9 Interrupt 9 */
                                                /* Interrupts 10 .. 223 are left out */
    };

    /*----------------------------------------------------------------------------
      Reset Handler called on controller reset
     *----------------------------------------------------------------------------*/
    void Reset_Handler(void)
    {
      SystemInit();                             /* CMSIS System Initialization */
      __PROGRAM_START();                        /* Enter PreMain (C library entry point) */
    }

    /*----------------------------------------------------------------------------
      Default Handler for Exceptions / Interrupts
     *----------------------------------------------------------------------------*/
    void Default_Handler(void)
    {
      while(1);
    }