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   <div id="projectbrief">CMSIS-Core support for Cortex-M processor-based devices</div>
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<div class="title">System Configuration Files system_&lt;device&gt;.c and system_&lt;device&gt;.h </div>  </div>
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<div class="textblock"><p>The <a class="el" href="system_c_pg.html">System Configuration Files system_&lt;device&gt;.c and system_&lt;device&gt;.h</a> provides as a minimum the functions described under <a class="el" href="group__system__init__gr.html">System and Clock Configuration</a>. These functions are device specific and need adaptations. In addition, the file might have configuration settings for the device such as XTAL frequency or PLL prescaler settings.</p>
<p>For devices with external memory BUS the system_&lt;device&gt;.c also configures the BUS system.</p>
<p>The silicon vendor might expose other functions (i.e. for power configuration) in the system_&lt;device&gt;.c file. In case of additional features the function prototypes need to be added to the system_&lt;device&gt;.h header file.</p>
<h1><a class="anchor" id="system_Device_sec"></a>
system_Device.c Template File</h1>
<p>The <a class="el" href="system_c_pg.html#system_Device_sec">system_Device.c Template File</a> for the Cortex-M3 is shown below.</p>
<pre class="fragment">/**************************************************************************//**
 * @file     system_&lt;Device&gt;.c
 * @brief    CMSIS Cortex-M# Device Peripheral Access Layer Source File for
 *           Device &lt;Device&gt;
 * @version  V5.00
 * @date     10. January 2018
 ******************************************************************************/
/*
 * Copyright (c) 2009-2018 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 &lt;stdint.h&gt;
#include "&lt;Device&gt;.h"


/*----------------------------------------------------------------------------
  Define clocks
 *----------------------------------------------------------------------------*/
/* ToDo: add here your necessary defines for device initialization
         following is an example for different system frequencies */
#define XTAL            (12000000U)       /* Oscillator frequency             */

#define SYSTEM_CLOCK    (5 * XTAL)


/*----------------------------------------------------------------------------
  System Core Clock Variable
 *----------------------------------------------------------------------------*/
/* ToDo: initialize SystemCoreClock with the system core clock frequency value
         achieved after system intitialization.
         This means system core clock frequency after call to SystemInit() */
uint32_t SystemCoreClock = SYSTEM_CLOCK;  /* System Clock Frequency (Core Clock)*/


/*----------------------------------------------------------------------------
  Clock functions
 *----------------------------------------------------------------------------*/

void SystemCoreClockUpdate (void)            /* Get Core Clock Frequency      */
{
/* ToDo: add code to calculate the system frequency based upon the current
         register settings.
         This function can be used to retrieve the system core clock frequeny
         after user changed register sittings. */
  SystemCoreClock = SYSTEM_CLOCK;
}

void SystemInit (void)
{
/* ToDo: add code to initialize the system
         do not use global variables because this function is called before
         reaching pre-main. RW section maybe overwritten afterwards. */
  SystemCoreClock = SYSTEM_CLOCK;
}
</pre><h1><a class="anchor" id="system_Device_h_sec"></a>
system_Device.h Template File</h1>
<p>The system_&lt;device&gt;.h header file contains prototypes to access the public functions in the system_&lt;device&gt;.c file. The <a class="el" href="system_c_pg.html#system_Device_h_sec">system_Device.h Template File</a> is shown below.</p>
<pre class="fragment">/**************************************************************************//**
 * @file     system_&lt;Device&gt;.h
 * @brief    CMSIS Cortex-M# Device Peripheral Access Layer Header File for
 *           Device &lt;Device&gt;
 * @version  V5.00
 * @date     10. January 2018
 ******************************************************************************/
/*
 * Copyright (c) 2009-2018 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.
 */

#ifndef SYSTEM_&lt;Device&gt;_H   /* ToDo: replace '&lt;Device&gt;' with your device name */
#define SYSTEM_&lt;Device&gt;_H

#ifdef __cplusplus
extern "C" {
#endif

#include &lt;stdint.h&gt;

extern uint32_t SystemCoreClock;     /*!&lt; System Clock Frequency (Core Clock)  */


/**
  \brief Setup the microcontroller system.

   Initialize the System and update the SystemCoreClock variable.
 */
extern void SystemInit (void);


/**
  \brief  Update SystemCoreClock variable.

   Updates the SystemCoreClock with current core Clock retrieved from cpu registers.
 */
extern void SystemCoreClockUpdate (void);


#ifdef __cplusplus
}
#endif

#endif /* SYSTEM_&lt;Device&gt;_H */
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