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<body>
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<h1>Cortex Microcontroller Software Interface Standard</h1>
60
 
61
<p align="center">This file describes the Cortex Microcontroller Software Interface Standard (CMSIS).</p>
62
<p align="center">Version: 1.30 - 30. October 2009</p>
63
 
64
<p class="TinyT">Information in this file, the accompany manuals, and software is<br>
65
                 Copyright © ARM Ltd.<br>All rights reserved.
66
</p>
67
 
68
<hr>
69
 
70
<p><span style="FONT-WEIGHT: bold">Revision History</span></p>
71
<ul>
72
        <li>Version 1.00: initial release. </li>
73
        <li>Version 1.01: added __LDREX<em>x</em>, __STREX<em>x</em>, and __CLREX.</li>
74
        <li>Version 1.02: added Cortex-M0. </li>
75
        <li>Version 1.10: second review. </li>
76
        <li>Version 1.20: third review. </li>
77
        <li>Version 1.30 PRE-RELEASE: reworked Startup Concept, additional Debug Functionality.</li>
78
        <li>Version 1.30 2nd PRE-RELEASE: changed folder structure, added doxyGen comments, added Bit definitions.</li>
79
        <li>Version 1.30: updated Device Support Packages.</li>
80
</ul>
81
 
82
<hr>
83
 
84
<h2>Contents</h2>
85
 
86
<ol>
87
  <li class="LI2"><a href="#1">About</a></li>
88
  <li class="LI2"><a href="#2">Coding Rules and Conventions</a></li>
89
  <li class="LI2"><a href="#3">CMSIS Files</a></li>
90
  <li class="LI2"><a href="#4">Core Peripheral Access Layer</a></li>
91
  <li class="LI2"><a href="#5">CMSIS Example</a></li>
92
</ol>
93
 
94
<h2><a name="1"></a>About</h2>
95
 
96
<p>
97
  The <strong>Cortex Microcontroller Software Interface Standard (CMSIS)</strong> answers the challenges
98
  that are faced when software components are deployed to physical microcontroller devices based on a
99
  Cortex-M0 or Cortex-M3 processor. The CMSIS will be also expanded to future Cortex-M
100
  processor cores (the term Cortex-M is used to indicate that). The CMSIS is defined in close co-operation
101
  with various silicon and software vendors and provides a common approach to interface to peripherals,
102
  real-time operating systems, and middleware components.
103
</p>
104
 
105
<p>ARM provides as part of the CMSIS the following software layers that are
106
available for various compiler implementations:</p>
107
<ul>
108
  <li><strong>Core Peripheral Access Layer</strong>: contains name definitions,
109
    address definitions and helper functions to
110
    access core registers and peripherals. It defines also a device
111
    independent interface for RTOS Kernels that includes debug channel
112
    definitions.</li>
113
</ul>
114
 
115
<p>These software layers are expanded by Silicon partners with:</p>
116
<ul>
117
  <li><strong>Device Peripheral Access Layer</strong>: provides definitions
118
    for all device peripherals</li>
119
  <li><strong>Access Functions for Peripherals (optional)</strong>: provides
120
    additional helper functions for peripherals</li>
121
</ul>
122
 
123
<p>CMSIS defines for a Cortex-M Microcontroller System:</p>
124
<ul>
125
  <li style="text-align: left;">A common way to access peripheral registers
126
    and a common way to define exception vectors.</li>
127
  <li style="text-align: left;">The register names of the <strong>Core
128
    Peripherals</strong> and<strong> </strong>the names of the <strong>Core
129
    Exception Vectors</strong>.</li>
130
  <li>An device independent interface for RTOS Kernels including a debug
131
    channel.</li>
132
</ul>
133
 
134
<p>
135
  By using CMSIS compliant software components, the user can easier re-use template code.
136
  CMSIS is intended to enable the combination of software components from multiple middleware vendors.
137
</p>
138
 
139
<h2><a name="2"></a>Coding Rules and Conventions</h2>
140
 
141
<p>
142
  The following section describes the coding rules and conventions used in the CMSIS
143
  implementation. It contains also information about data types and version number information.
144
</p>
145
 
146
<h3>Essentials</h3>
147
<ul>
148
  <li>The CMSIS C code conforms to MISRA 2004 rules. In case of MISRA violations,
149
      there are disable and enable sequences for PC-LINT inserted.</li>
150
  <li>ANSI standard data types defined in the ANSI C header file
151
    <strong>&lt;stdint.h&gt;</strong> are used.</li>
152
  <li>#define constants that include expressions must be enclosed by
153
    parenthesis.</li>
154
  <li>Variables and parameters have a complete data type.</li>
155
  <li>All functions in the <strong>Core Peripheral Access Layer</strong> are
156
    re-entrant.</li>
157
  <li>The <strong>Core Peripheral Access Layer</strong> has no blocking code
158
    (which means that wait/query loops are done at other software layers).</li>
159
  <li>For each exception/interrupt there is definition for:
160
  <ul>
161
    <li>an exception/interrupt handler with the postfix <strong>_Handler </strong>
162
        (for exceptions) or <strong>_IRQHandler</strong> (for interrupts).</li>
163
    <li>a default exception/interrupt handler (weak definition) that contains an endless loop.</li>
164
    <li>a #define of the interrupt number with the postfix <strong>_IRQn</strong>.</li>
165
  </ul></li>
166
</ul>
167
 
168
<h3>Recommendations</h3>
169
 
170
<p>The CMSIS recommends the following conventions for identifiers.</p>
171
<ul>
172
  <li><strong>CAPITAL</strong> names to identify Core Registers, Peripheral Registers, and CPU Instructions.</li>
173
  <li><strong>CamelCase</strong> names to identify peripherals access functions and interrupts.</li>
174
  <li><strong>PERIPHERAL_</strong> prefix to identify functions that belong to specify peripherals.</li>
175
  <li><strong>Doxygen</strong> comments for all functions are included as described under <strong>Function Comments</strong> below.</li>
176
</ul>
177
 
178
<b>Comments</b>
179
 
180
<ul>
181
  <li>Comments use the ANSI C90 style (<em>/* comment */</em>) or C++ style
182
  (<em>// comment</em>). It is assumed that the programming tools support today
183
        consistently the C++ comment style.</li>
184
  <li><strong>Function Comments</strong> provide for each function the following information:
185
  <ul>
186
    <li>one-line brief function overview.</li>
187
    <li>detailed parameter explanation.</li>
188
    <li>detailed information about return values.</li>
189
    <li>detailed description of the actual function.</li>
190
  </ul>
191
  <p><b>Doxygen Example:</b></p>
192
  <pre>
193
/**
194
 * @brief  Enable Interrupt in NVIC Interrupt Controller
195
 * @param  IRQn  interrupt number that specifies the interrupt
196
 * @return none.
197
 * Enable the specified interrupt in the NVIC Interrupt Controller.
198
 * Other settings of the interrupt such as priority are not affected.
199
 */</pre>
200
  </li>
201
</ul>
202
 
203
<h3>Data Types and IO Type Qualifiers</h3>
204
 
205
<p>
206
  The <strong>Cortex-M HAL</strong> uses the standard types from the standard ANSI C header file
207
  <strong>&lt;stdint.h&gt;</strong>. <strong>IO Type Qualifiers</strong> are used to specify the access
208
  to peripheral variables. IO Type Qualifiers are indented to be used for automatic generation of
209
  debug information of peripheral registers.
210
</p>
211
 
212
<table class="kt" border="0" cellpadding="0" cellspacing="0">
213
  <tbody>
214
    <tr>
215
      <th class="kt" nowrap="nowrap">IO Type Qualifier</th>
216
      <th class="kt">#define</th>
217
      <th class="kt">Description</th>
218
    </tr>
219
    <tr>
220
      <td class="kt" nowrap="nowrap">__I</td>
221
      <td class="kt">volatile const</td>
222
      <td class="kt">Read access only</td>
223
    </tr>
224
    <tr>
225
      <td class="kt" nowrap="nowrap">__O</td>
226
      <td class="kt">volatile</td>
227
      <td class="kt">Write access only</td>
228
    </tr>
229
    <tr>
230
      <td class="kt" nowrap="nowrap">__IO</td>
231
      <td class="kt">volatile</td>
232
      <td class="kt">Read and write access</td>
233
    </tr>
234
  </tbody>
235
</table>
236
 
237
<h3>CMSIS Version Number</h3>
238
<p>
239
  File <strong>core_cm3.h</strong> contains the version number of the CMSIS with the following define:
240
</p>
241
 
242
<pre>
243
#define __CM3_CMSIS_VERSION_MAIN  (0x01)      /* [31:16] main version       */
244
#define __CM3_CMSIS_VERSION_SUB   (0x30)      /* [15:0]  sub version        */
245
#define __CM3_CMSIS_VERSION       ((__CM3_CMSIS_VERSION_MAIN &lt;&lt; 16) | __CM3_CMSIS_VERSION_SUB)</pre>
246
 
247
<p>
248
  File <strong>core_cm0.h</strong> contains the version number of the CMSIS with the following define:
249
</p>
250
 
251
<pre>
252
#define __CM0_CMSIS_VERSION_MAIN  (0x01)      /* [31:16] main version       */
253
#define __CM0_CMSIS_VERSION_SUB   (0x30)      /* [15:0]  sub version        */
254
#define __CM0_CMSIS_VERSION       ((__CM0_CMSIS_VERSION_MAIN &lt;&lt; 16) | __CM0_CMSIS_VERSION_SUB)</pre>
255
 
256
 
257
<h3>CMSIS Cortex Core</h3>
258
<p>
259
  File <strong>core_cm3.h</strong> contains the type of the CMSIS Cortex-M with the following define:
260
</p>
261
 
262
<pre>
263
#define __CORTEX_M                (0x03)</pre>
264
 
265
<p>
266
  File <strong>core_cm0.h</strong> contains the type of the CMSIS Cortex-M with the following define:
267
</p>
268
 
269
<pre>
270
#define __CORTEX_M                (0x00)</pre>
271
 
272
 
273
<h2><a name="3"></a>CMSIS Files</h2>
274
<p>
275
  This section describes the Files provided in context with the CMSIS to access the Cortex-M
276
  hardware and peripherals.
277
</p>
278
 
279
<table class="kt" border="0" cellpadding="0" cellspacing="0">
280
  <tbody>
281
    <tr>
282
      <th class="kt" nowrap="nowrap">File</th>
283
      <th class="kt">Provider</th>
284
      <th class="kt">Description</th>
285
    </tr>
286
    <tr>
287
      <td class="kt" nowrap="nowrap"><i>device.h</i></td>
288
      <td class="kt">Device specific (provided by silicon partner)</td>
289
      <td class="kt">Defines the peripherals for the actual device. The file may use
290
        several other include files to define the peripherals of the actual device.</td>
291
    </tr>
292
    <tr>
293
      <td class="kt" nowrap="nowrap">core_cm0.h</td>
294
      <td class="kt">ARM (for RealView ARMCC, IAR, and GNU GCC)</td>
295
      <td class="kt">Defines the core peripherals for the Cortex-M0 CPU and core peripherals.</td>
296
    </tr>
297
    <tr>
298
      <td class="kt" nowrap="nowrap">core_cm3.h</td>
299
      <td class="kt">ARM (for RealView ARMCC, IAR, and GNU GCC)</td>
300
      <td class="kt">Defines the core peripherals for the Cortex-M3 CPU and core peripherals.</td>
301
    </tr>
302
    <tr>
303
      <td class="kt" nowrap="nowrap">core_cm0.c</td>
304
      <td class="kt">ARM (for RealView ARMCC, IAR, and GNU GCC)</td>
305
      <td class="kt">Provides helper functions that access core registers.</td>
306
    </tr>
307
    <tr>
308
      <td class="kt" nowrap="nowrap">core_cm3.c</td>
309
      <td class="kt">ARM (for RealView ARMCC, IAR, and GNU GCC)</td>
310
      <td class="kt">Provides helper functions that access core registers.</td>
311
    </tr>
312
    <tr>
313
      <td class="kt" nowrap="nowrap">startup<i>_device</i></td>
314
      <td class="kt">ARM (adapted by compiler partner / silicon partner)</td>
315
      <td class="kt">Provides the Cortex-M startup code and the complete (device specific) Interrupt Vector Table</td>
316
    </tr>
317
    <tr>
318
      <td class="kt" nowrap="nowrap">system<i>_device</i></td>
319
      <td class="kt">ARM (adapted by silicon partner)</td>
320
      <td class="kt">Provides a device specific configuration file for the device. It configures the device initializes
321
        typically the oscillator (PLL) that is part of the microcontroller device</td>
322
    </tr>
323
  </tbody>
324
</table>
325
 
326
<h3><em>device.h</em></h3>
327
 
328
<p>
329
  The file <em><strong>device.h</strong></em> is provided by the silicon vendor and is the
330
  <u><strong>central include file</strong></u> that the application programmer is using in
331
  the C source code. This file contains:
332
</p>
333
<ul>
334
  <li>
335
        <p><strong>Interrupt Number Definition</strong>: provides interrupt numbers
336
        (IRQn) for all core and device specific exceptions and interrupts.</p>
337
        </li>
338
        <li>
339
        <p><strong>Configuration for core_cm0.h / core_cm3.h</strong>: reflects the
340
        actual configuration of the Cortex-M processor that is part of the actual
341
        device. As such the file <strong>core_cm0.h / core_cm3.h</strong> is included that
342
        implements access to processor registers and core peripherals. </p>
343
        </li>
344
        <li>
345
        <p><strong>Device Peripheral Access Layer</strong>: provides definitions
346
    for all device peripherals. It contains all data structures and the address
347
        mapping for the device specific peripherals. </p>
348
        </li>
349
  <li><strong>Access Functions for Peripherals (optional)</strong>: provides
350
    additional helper functions for peripherals that are useful for programming
351
        of these peripherals. Access Functions may be provided as inline functions
352
        or can be extern references to a device specific library provided by the
353
        silicon vendor.</li>
354
</ul>
355
 
356
 
357
<h4><strong>Interrupt Number Definition</strong></h4>
358
 
359
<p>To access the device specific interrupts the device.h file defines IRQn
360
numbers for the complete device using a enum typedef as shown below:</p>
361
<pre>
362
typedef enum IRQn
363
{
364
/******  Cortex-M3 Processor Exceptions/Interrupt Numbers ************************************************/
365
  NonMaskableInt_IRQn             = -14,      /*!&lt; 2 Non Maskable Interrupt                              */
366
  HardFault_IRQn                  = -13,      /*!&lt; 3 Cortex-M3 Hard Fault Interrupt                      */
367
  MemoryManagement_IRQn           = -12,      /*!&lt; 4 Cortex-M3 Memory Management Interrupt               */
368
  BusFault_IRQn                   = -11,      /*!&lt; 5 Cortex-M3 Bus Fault Interrupt                       */
369
  UsageFault_IRQn                 = -10,      /*!&lt; 6 Cortex-M3 Usage Fault Interrupt                     */
370
  SVCall_IRQn                     = -5,       /*!&lt; 11 Cortex-M3 SV Call Interrupt                        */
371
  DebugMonitor_IRQn               = -4,       /*!&lt; 12 Cortex-M3 Debug Monitor Interrupt                  */
372
  PendSV_IRQn                     = -2,       /*!&lt; 14 Cortex-M3 Pend SV Interrupt                        */
373
  SysTick_IRQn                    = -1,       /*!&lt; 15 Cortex-M3 System Tick Interrupt                    */
374
/******  STM32 specific Interrupt Numbers ****************************************************************/
375
  WWDG_STM_IRQn                   = 0,        /*!&lt; Window WatchDog Interrupt                             */
376
  PVD_STM_IRQn                    = 1,        /*!&lt; PVD through EXTI Line detection Interrupt             */
377
  :
378
  :
379
  } IRQn_Type;</pre>
380
 
381
 
382
<h4>Configuration for core_cm0.h / core_cm3.h</h4>
383
<p>
384
  The Cortex-M core configuration options which are defined for each device implementation. Some
385
  configuration options are reflected in the CMSIS layer using the #define settings described below.
386
</p>
387
<p>
388
  To access core peripherals file <em><strong>device.h</strong></em> includes file <b>core_cm0.h / core_cm3.h</b>.
389
  Several features in <strong>core_cm0.h / core_cm3.h</strong> are configured by the following defines that must be
390
  defined before <strong>#include &lt;core_cm0.h&gt;</strong> / <strong>#include &lt;core_cm3.h&gt;</strong>
391
  preprocessor command.
392
</p>
393
 
394
<table class="kt" border="0" cellpadding="0" cellspacing="0">
395
  <tbody>
396
    <tr>
397
      <th class="kt" nowrap="nowrap">#define</th>
398
      <th class="kt" nowrap="nowrap">File</th>
399
      <th class="kt" nowrap="nowrap">Value</th>
400
      <th class="kt">Description</th>
401
    </tr>
402
    <tr>
403
      <td class="kt" nowrap="nowrap">__NVIC_PRIO_BITS</td>
404
      <td class="kt">core_cm0.h</td>
405
      <td class="kt" nowrap="nowrap">(2)</td>
406
      <td class="kt">Number of priority bits implemented in the NVIC (device specific)</td>
407
    </tr>
408
    <tr>
409
      <td class="kt" nowrap="nowrap">__NVIC_PRIO_BITS</td>
410
      <td class="kt">core_cm3.h</td>
411
      <td class="kt" nowrap="nowrap">(2 ... 8)</td>
412
      <td class="kt">Number of priority bits implemented in the NVIC (device specific)</td>
413
    </tr>
414
    <tr>
415
      <td class="kt" nowrap="nowrap">__MPU_PRESENT</td>
416
      <td class="kt">core_cm0.h, core_cm3.h</td>
417
      <td class="kt" nowrap="nowrap">(0, 1)</td>
418
      <td class="kt">Defines if an MPU is present or not</td>
419
    </tr>
420
    <tr>
421
      <td class="kt" nowrap="nowrap">__Vendor_SysTickConfig</td>
422
      <td class="kt">core_cm0.h, core_cm3.h</td>
423
      <td class="kt" nowrap="nowrap">(1)</td>
424
      <td class="kt">When this define is setup to 1, the <strong>SysTickConfig</strong> function
425
                in <strong>core_cm3.h</strong> is excluded. In this case the <em><strong>device.h</strong></em>
426
                file must contain a vendor specific implementation of this function.</td>
427
    </tr>
428
  </tbody>
429
</table>
430
 
431
 
432
<h4>Device Peripheral Access Layer</h4>
433
<p>
434
  Each peripheral uses a prefix which consists of <strong>&lt;device abbreviation&gt;_</strong>
435
  and <strong>&lt;peripheral name&gt;_</strong> to identify peripheral registers that access this
436
  specific peripheral. The intention of this is to avoid name collisions caused
437
  due to short names. If more than one peripheral of the same type exists,
438
  identifiers have a postfix (digit or letter). For example:
439
</p>
440
<ul>
441
        <li>&lt;device abbreviation&gt;_UART_Type: defines the generic register layout for all UART channels in a device.
442
      <pre>
443
typedef struct
444
{
445
  union {
446
  __I  uint8_t  RBR;                     /*!< Offset: 0x000   Receiver Buffer Register    */
447
  __O  uint8_t  THR;                     /*!< Offset: 0x000   Transmit Holding Register   */
448
  __IO uint8_t  DLL;                     /*!< Offset: 0x000   Divisor Latch LSB           */
449
       uint32_t RESERVED0;
450
  };
451
  union {
452
  __IO uint8_t  DLM;                     /*!< Offset: 0x004   Divisor Latch MSB           */
453
  __IO uint32_t IER;                     /*!< Offset: 0x004   Interrupt Enable Register   */
454
  };
455
  union {
456
  __I  uint32_t IIR;                     /*!< Offset: 0x008   Interrupt ID Register       */
457
  __O  uint8_t  FCR;                     /*!< Offset: 0x008   FIFO Control Register       */
458
  };
459
  __IO uint8_t  LCR;                     /*!< Offset: 0x00C   Line Control Register       */
460
       uint8_t  RESERVED1[7];
461
  __I  uint8_t  LSR;                     /*!< Offset: 0x014   Line Status Register        */
462
       uint8_t  RESERVED2[7];
463
  __IO uint8_t  SCR;                     /*!< Offset: 0x01C   Scratch Pad Register        */
464
       uint8_t  RESERVED3[3];
465
  __IO uint32_t ACR;                     /*!< Offset: 0x020   Autobaud Control Register   */
466
  __IO uint8_t  ICR;                     /*!< Offset: 0x024   IrDA Control Register       */
467
       uint8_t  RESERVED4[3];
468
  __IO uint8_t  FDR;                     /*!< Offset: 0x028   Fractional Divider Register */
469
       uint8_t  RESERVED5[7];
470
  __IO uint8_t  TER;                     /*!< Offset: 0x030   Transmit Enable Register    */
471
       uint8_t  RESERVED6[39];
472
  __I  uint8_t  FIFOLVL;                 /*!< Offset: 0x058   FIFO Level Register         */
473
} LPC_UART_TypeDef;</pre>
474
  </li>
475
        <li>&lt;device abbreviation&gt;_UART1: is a pointer to a register structure that refers to a specific UART.
476
      For example UART1-&gt;DR is the data register of UART1.
477
      <pre>
478
#define LPC_UART2             ((LPC_UART_TypeDef      *) LPC_UART2_BASE    )
479
#define LPC_UART3             ((LPC_UART_TypeDef      *) LPC_UART3_BASE    )</pre>
480
  </li>
481
</ul>
482
 
483
<h5>Minimal Requiements</h5>
484
<p>
485
  To access the peripheral registers and related function in a device the files <strong><em>device.h</em></strong>
486
  and <strong>core_cm0.h</strong> / <strong>core_cm3.h</strong> defines as a minimum:
487
</p>
488
<ul>
489
  <li>The <strong>Register Layout Typedef</strong> for each peripheral that defines all register names.
490
      Names that start with RESERVE are used to introduce space into the structure to adjust the addresses of
491
      the peripheral registers. For example:
492
      <pre>
493
typedef struct {
494
  __IO uint32_t CTRL;      /* SysTick Control and Status Register */
495
  __IO uint32_t LOAD;      /* SysTick Reload Value Register       */
496
  __IO uint32_t VAL;       /* SysTick Current Value Register      */
497
  __I  uint32_t CALIB;     /* SysTick Calibration Register        */
498
  } SysTick_Type;</pre>
499
  </li>
500
 
501
  <li>
502
    <strong>Base Address</strong> for each peripheral (in case of multiple peripherals
503
    that use the same <strong>register layout typedef</strong> multiple base addresses are defined). For example:
504
    <pre>
505
#define SysTick_BASE (SCS_BASE + 0x0010)            /* SysTick Base Address */</pre>
506
  </li>
507
 
508
  <li>
509
    <strong>Access Definition</strong> for each peripheral (in case of multiple peripherals that use
510
    the same <strong>register layout typedef</strong> multiple access definitions exist, i.e. LPC_UART0,
511
    LPC_UART2). For Example:
512
    <pre>
513
#define SysTick ((SysTick_Type *) SysTick_BASE)     /* SysTick access definition */</pre>
514
  </li>
515
</ul>
516
 
517
<p>
518
  These definitions allow to access the peripheral registers from user code with simple assignments like:
519
</p>
520
<pre>SysTick-&gt;CTRL = 0;</pre>
521
 
522
<h5>Optional Features</h5>
523
<p>In addition the <em> <strong>device.h </strong></em>file may define:</p>
524
<ul>
525
        <li>
526
    #define constants that simplify access to the peripheral registers.
527
          These constant define bit-positions or other specific patterns are that required for the
528
    programming of the peripheral registers. The identifiers used start with
529
    <strong>&lt;device abbreviation&gt;_</strong> and <strong>&lt;peripheral name&gt;_</strong>.
530
    It is recommended to use CAPITAL letters for such #define constants.
531
  </li>
532
        <li>
533
    Functions that perform more complex functions with the peripheral (i.e. status query before
534
    a sending register is accessed). Again these function start with
535
    <strong>&lt;device abbreviation&gt;_</strong> and <strong>&lt;peripheral name&gt;_</strong>.
536
  </li>
537
</ul>
538
 
539
<h3>core_cm0.h and core_cm0.c</h3>
540
<p>
541
  File <b>core_cm0.h</b> describes the data structures for the Cortex-M0 core peripherals and does
542
  the address mapping of this structures. It also provides basic access to the Cortex-M0 core registers
543
  and core peripherals with efficient functions (defined as <strong>static inline</strong>).
544
</p>
545
<p>
546
  File <b>core_cm0.c</b> defines several helper functions that access processor registers.
547
</p>
548
<p>Together these files implement the <a href="#4">Core Peripheral Access Layer</a> for a Cortex-M0.</p>
549
 
550
<h3>core_cm3.h and core_cm3.c</h3>
551
<p>
552
  File <b>core_cm3.h</b> describes the data structures for the Cortex-M3 core peripherals and does
553
  the address mapping of this structures. It also provides basic access to the Cortex-M3 core registers
554
  and core peripherals with efficient functions (defined as <strong>static inline</strong>).
555
</p>
556
<p>
557
  File <b>core_cm3.c</b> defines several helper functions that access processor registers.
558
</p>
559
<p>Together these files implement the <a href="#4">Core Peripheral Access Layer</a> for a Cortex-M3.</p>
560
 
561
<h3>startup_<em>device</em></h3>
562
<p>
563
  A template file for <strong>startup_<em>device</em></strong> is provided by ARM for each supported
564
  compiler. It is adapted by the silicon vendor to include interrupt vectors for all device specific
565
  interrupt handlers. Each interrupt handler is defined as <strong><em>weak</em></strong> function
566
  to an dummy handler. Therefore the interrupt handler can be directly used in application software
567
  without any requirements to adapt the <strong>startup_<em>device</em></strong> file.
568
</p>
569
<p>
570
  The following exception names are fixed and define the start of the vector table for a Cortex-M0:
571
</p>
572
<pre>
573
__Vectors       DCD     __initial_sp              ; Top of Stack
574
                DCD     Reset_Handler             ; Reset Handler
575
                DCD     NMI_Handler               ; NMI Handler
576
                DCD     HardFault_Handler         ; Hard Fault Handler
577
                DCD     0                         ; Reserved
578
                DCD     0                         ; Reserved
579
                DCD     0                         ; Reserved
580
                DCD     0                         ; Reserved
581
                DCD     0                         ; Reserved
582
                DCD     0                         ; Reserved
583
                DCD     0                         ; Reserved
584
                DCD     SVC_Handler               ; SVCall Handler
585
                DCD     0                         ; Reserved
586
                DCD     0                         ; Reserved
587
                DCD     PendSV_Handler            ; PendSV Handler
588
                DCD     SysTick_Handler           ; SysTick Handler</pre>
589
 
590
<p>
591
  The following exception names are fixed and define the start of the vector table for a Cortex-M3:
592
</p>
593
<pre>
594
__Vectors       DCD     __initial_sp              ; Top of Stack
595
                DCD     Reset_Handler             ; Reset Handler
596
                DCD     NMI_Handler               ; NMI Handler
597
                DCD     HardFault_Handler         ; Hard Fault Handler
598
                DCD     MemManage_Handler         ; MPU Fault Handler
599
                DCD     BusFault_Handler          ; Bus Fault Handler
600
                DCD     UsageFault_Handler        ; Usage Fault Handler
601
                DCD     0                         ; Reserved
602
                DCD     0                         ; Reserved
603
                DCD     0                         ; Reserved
604
                DCD     0                         ; Reserved
605
                DCD     SVC_Handler               ; SVCall Handler
606
                DCD     DebugMon_Handler          ; Debug Monitor Handler
607
                DCD     0                         ; Reserved
608
                DCD     PendSV_Handler            ; PendSV Handler
609
                DCD     SysTick_Handler           ; SysTick Handler</pre>
610
 
611
<p>
612
  In the following examples for device specific interrupts are shown:
613
</p>
614
<pre>
615
; External Interrupts
616
                DCD     WWDG_IRQHandler           ; Window Watchdog
617
                DCD     PVD_IRQHandler            ; PVD through EXTI Line detect
618
                DCD     TAMPER_IRQHandler         ; Tamper</pre>
619
 
620
<p>
621
  Device specific interrupts must have a dummy function that can be overwritten in user code.
622
  Below is an example for this dummy function.
623
</p>
624
<pre>
625
Default_Handler PROC
626
                EXPORT WWDG_IRQHandler   [WEAK]
627
                EXPORT PVD_IRQHandler    [WEAK]
628
                EXPORT TAMPER_IRQHandler [WEAK]
629
                :
630
                :
631
                WWDG_IRQHandler
632
                PVD_IRQHandler
633
                TAMPER_IRQHandler
634
                :
635
                :
636
                B .
637
                ENDP</pre>
638
 
639
<p>
640
  The user application may simply define an interrupt handler function by using the handler name
641
  as shown below.
642
</p>
643
<pre>
644
void WWDG_IRQHandler(void)
645
{
646
  :
647
  :
648
}</pre>
649
 
650
 
651
<h3><a name="4"></a>system_<em>device</em>.c</h3>
652
<p>
653
  A template file for <strong>system_<em>device</em>.c</strong> is provided by ARM but adapted by
654
  the silicon vendor to match their actual device. As a <strong>minimum requirement</strong>
655
  this file must provide a device specific system configuration function and a global variable
656
  that contains the system frequency. It configures the device and initializes typically the
657
  oscillator (PLL) that is part of the microcontroller device.
658
</p>
659
<p>
660
  The file <strong>system_</strong><em><strong>device</strong></em><strong>.c</strong> must provide
661
  as a minimum requirement the SystemInit function as shown below.
662
</p>
663
 
664
<table class="kt" border="0" cellpadding="0" cellspacing="0">
665
  <tbody>
666
    <tr>
667
      <th class="kt">Function Definition</th>
668
      <th class="kt">Description</th>
669
    </tr>
670
    <tr>
671
      <td class="kt" nowrap="nowrap">void SystemInit (void)</td>
672
      <td class="kt">Setup the microcontroller system. Typically this function configures the
673
                     oscillator (PLL) that is part of the microcontroller device. For systems
674
                     with variable clock speed it also updates the variable SystemCoreClock.<br>
675
                     SystemInit is called from startup<i>_device</i> file.</td>
676
    </tr>
677
    <tr>
678
      <td class="kt" nowrap="nowrap">void SystemCoreClockUpdate (void)</td>
679
      <td class="kt">Updates the variable SystemCoreClock and must be called whenever the
680
                     core clock is changed during program execution. SystemCoreClockUpdate()
681
                     evaluates the clock register settings and calculates the current core clock.
682
</td>
683
    </tr>
684
  </tbody>
685
</table>
686
 
687
<p>
688
  Also part of the file <strong>system_</strong><em><strong>device</strong></em><strong>.c</strong>
689
  is the variable <strong>SystemCoreClock</strong> which contains the current CPU clock speed shown below.
690
</p>
691
 
692
<table class="kt" border="0" cellpadding="0" cellspacing="0">
693
  <tbody>
694
    <tr>
695
      <th class="kt">Variable Definition</th>
696
      <th class="kt">Description</th>
697
    </tr>
698
    <tr>
699
      <td class="kt" nowrap="nowrap">uint32_t SystemCoreClock</td>
700
      <td class="kt">Contains the system core clock (which is the system clock  frequency supplied
701
                     to the SysTick timer and the processor core clock). This variable can be
702
                     used by the user application to setup the SysTick timer or configure other
703
                     parameters. It may also be used by debugger to query the frequency of the
704
                     debug timer or configure the trace clock speed.<br>
705
                     SystemCoreClock is initialized with a correct predefined value.<br><br>
706
                                 The compiler must be configured to avoid the removal of this variable in
707
                                 case that the application program is not using it. It is important for
708
                                 debug systems that the variable is physically present in memory so that
709
                                 it can be examined to configure the debugger.</td>
710
    </tr>
711
  </tbody>
712
</table>
713
 
714
<p class="Note">Note</p>
715
<ul>
716
  <li><p>The above definitions are the minimum requirements for the file <strong>
717
        system_</strong><em><strong>device</strong></em><strong>.c</strong>. This
718
        file may export more functions or variables that provide a more flexible
719
        configuration of the microcontroller system.</p>
720
  </li>
721
</ul>
722
 
723
 
724
<h2>Core Peripheral Access Layer</h2>
725
 
726
<h3>Cortex-M Core Register Access</h3>
727
<p>
728
  The following functions are defined in <strong>core_cm0.h</strong> / <strong>core_cm3.h</strong>
729
  and provide access to Cortex-M core registers.
730
</p>
731
 
732
<table class="kt" border="0" cellpadding="0" cellspacing="0">
733
  <tbody>
734
    <tr>
735
      <th class="kt">Function Definition</th>
736
      <th class="kt">Core</th>
737
      <th class="kt">Core Register</th>
738
      <th class="kt">Description</th>
739
    </tr>
740
    <tr>
741
      <td class="kt" nowrap="nowrap">void __enable_irq (void)</td>
742
      <td class="kt">M0, M3</td>
743
      <td class="kt">PRIMASK = 0</td>
744
      <td class="kt">Global Interrupt enable (using the instruction <strong>CPSIE
745
                i</strong>)</td>
746
    </tr>
747
    <tr>
748
      <td class="kt" nowrap="nowrap">void __disable_irq (void)</td>
749
      <td class="kt">M0, M3</td>
750
      <td class="kt">PRIMASK = 1</td>
751
      <td class="kt">Global Interrupt disable (using the instruction <strong>
752
                CPSID i</strong>)</td>
753
    </tr>
754
    <tr>
755
      <td class="kt" nowrap="nowrap">void __set_PRIMASK (uint32_t value)</td>
756
      <td class="kt">M0, M3</td>
757
      <td class="kt">PRIMASK = value</td>
758
      <td class="kt">Assign value to Priority Mask Register (using the instruction
759
                <strong>MSR</strong>)</td>
760
    </tr>
761
    <tr>
762
      <td class="kt" nowrap="nowrap">uint32_t __get_PRIMASK (void)</td>
763
      <td class="kt">M0, M3</td>
764
      <td class="kt">return PRIMASK</td>
765
      <td class="kt">Return Priority Mask Register (using the instruction
766
                <strong>MRS</strong>)</td>
767
    </tr>
768
    <tr>
769
      <td class="kt" nowrap="nowrap">void __enable_fault_irq (void)</td>
770
      <td class="kt">M3</td>
771
      <td class="kt">FAULTMASK = 0</td>
772
      <td class="kt">Global Fault exception and Interrupt enable (using the
773
                instruction <strong>CPSIE
774
                f</strong>)</td>
775
    </tr>
776
    <tr>
777
      <td class="kt" nowrap="nowrap">void __disable_fault_irq (void)</td>
778
      <td class="kt">M3</td>
779
      <td class="kt">FAULTMASK = 1</td>
780
      <td class="kt">Global Fault exception and Interrupt disable (using the
781
                instruction <strong>CPSID f</strong>)</td>
782
    </tr>
783
    <tr>
784
      <td class="kt" nowrap="nowrap">void __set_FAULTMASK (uint32_t value)</td>
785
      <td class="kt">M3</td>
786
      <td class="kt">FAULTMASK = value</td>
787
      <td class="kt">Assign value to Fault Mask Register (using the instruction
788
                <strong>MSR</strong>)</td>
789
    </tr>
790
    <tr>
791
      <td class="kt" nowrap="nowrap">uint32_t __get_FAULTMASK (void)</td>
792
      <td class="kt">M3</td>
793
      <td class="kt">return FAULTMASK</td>
794
      <td class="kt">Return Fault Mask Register (using the instruction <strong>MRS</strong>)</td>
795
    </tr>
796
    <tr>
797
      <td class="kt" nowrap="nowrap">void __set_BASEPRI (uint32_t value)</td>
798
      <td class="kt">M3</td>
799
      <td class="kt">BASEPRI = value</td>
800
      <td class="kt">Set Base Priority (using the instruction <strong>MSR</strong>)</td>
801
    </tr>
802
    <tr>
803
      <td class="kt" nowrap="nowrap">uiuint32_t __get_BASEPRI (void)</td>
804
      <td class="kt">M3</td>
805
      <td class="kt">return BASEPRI</td>
806
      <td class="kt">Return Base Priority (using the instruction <strong>MRS</strong>)</td>
807
    </tr>
808
    <tr>
809
      <td class="kt" nowrap="nowrap">void __set_CONTROL (uint32_t value)</td>
810
      <td class="kt">M0, M3</td>
811
      <td class="kt">CONTROL = value</td>
812
      <td class="kt">Set CONTROL register value (using the instruction <strong>MSR</strong>)</td>
813
    </tr>
814
    <tr>
815
      <td class="kt" nowrap="nowrap">uint32_t __get_CONTROL (void)</td>
816
      <td class="kt">M0, M3</td>
817
      <td class="kt">return CONTROL</td>
818
      <td class="kt">Return Control Register Value (using the instruction
819
                <strong>MRS</strong>)</td>
820
    </tr>
821
    <tr>
822
      <td class="kt" nowrap="nowrap">void __set_PSP (uint32_t TopOfProcStack)</td>
823
      <td class="kt">M0, M3</td>
824
      <td class="kt">PSP = TopOfProcStack</td>
825
      <td class="kt">Set Process Stack Pointer value (using the instruction
826
                <strong>MSR</strong>)</td>
827
    </tr>
828
    <tr>
829
      <td class="kt" nowrap="nowrap">uint32_t __get_PSP (void)</td>
830
      <td class="kt">M0, M3</td>
831
      <td class="kt">return PSP</td>
832
      <td class="kt">Return Process Stack Pointer (using the instruction <strong>MRS</strong>)</td>
833
    </tr>
834
    <tr>
835
      <td class="kt" nowrap="nowrap">void __set_MSP (uint32_t TopOfMainStack)</td>
836
      <td class="kt">M0, M3</td>
837
      <td class="kt">MSP = TopOfMainStack</td>
838
      <td class="kt">Set Main Stack Pointer (using the instruction <strong>MSR</strong>)</td>
839
    </tr>
840
    <tr>
841
      <td class="kt" nowrap="nowrap">uint32_t __get_MSP (void)</td>
842
      <td class="kt">M0, M3</td>
843
      <td class="kt">return MSP</td>
844
      <td class="kt">Return Main Stack Pointer (using the instruction <strong>MRS</strong>)</td>
845
    </tr>
846
  </tbody>
847
</table>
848
 
849
<h3>Cortex-M Instruction Access</h3>
850
<p>
851
  The following functions are defined in <strong>core_cm0.h</strong> / <strong>core_cm3.h</strong>and
852
  generate specific Cortex-M instructions. The functions are implemented in the file
853
  <strong>core_cm0.c</strong> / <strong>core_cm3.c</strong>.
854
</p>
855
 
856
<table class="kt" border="0" cellpadding="0" cellspacing="0">
857
  <tbody>
858
    <tr>
859
      <th class="kt">Name</th>
860
      <th class="kt">Core</th>
861
      <th class="kt">Generated CPU Instruction</th>
862
      <th class="kt">Description</th>
863
    </tr>
864
    <tr>
865
      <td class="kt" nowrap="nowrap">void __NOP (void)</td>
866
      <td class="kt">M0, M3</td>
867
      <td class="kt">NOP</td>
868
      <td class="kt">No Operation</td>
869
    </tr>
870
    <tr>
871
      <td class="kt" nowrap="nowrap">void __WFI (void)</td>
872
      <td class="kt">M0, M3</td>
873
      <td class="kt">WFI</td>
874
      <td class="kt">Wait for Interrupt</td>
875
    </tr>
876
    <tr>
877
      <td class="kt" nowrap="nowrap">void __WFE (void)</td>
878
      <td class="kt">M0, M3</td>
879
      <td class="kt">WFE</td>
880
      <td class="kt">Wait for Event</td>
881
    </tr>
882
    <tr>
883
      <td class="kt" nowrap="nowrap">void __SEV (void)</td>
884
      <td class="kt">M0, M3</td>
885
      <td class="kt">SEV</td>
886
      <td class="kt">Set Event</td>
887
    </tr>
888
    <tr>
889
      <td class="kt" nowrap="nowrap">void __ISB (void)</td>
890
      <td class="kt">M0, M3</td>
891
      <td class="kt">ISB</td>
892
      <td class="kt">Instruction Synchronization Barrier</td>
893
    </tr>
894
    <tr>
895
      <td class="kt" nowrap="nowrap">void __DSB (void)</td>
896
      <td class="kt">M0, M3</td>
897
      <td class="kt">DSB</td>
898
      <td class="kt">Data Synchronization Barrier</td>
899
    </tr>
900
    <tr>
901
      <td class="kt" nowrap="nowrap">void __DMB (void)</td>
902
      <td class="kt">M0, M3</td>
903
      <td class="kt">DMB</td>
904
      <td class="kt">Data Memory Barrier</td>
905
    </tr>
906
    <tr>
907
      <td class="kt" nowrap="nowrap">uint32_t __REV (uint32_t value)</td>
908
      <td class="kt">M0, M3</td>
909
      <td class="kt">REV</td>
910
      <td class="kt">Reverse byte order in integer value.</td>
911
    </tr>
912
    <tr>
913
      <td class="kt" nowrap="nowrap">uint32_t __REV16 (uint16_t value)</td>
914
      <td class="kt">M0, M3</td>
915
      <td class="kt">REV16</td>
916
      <td class="kt">Reverse byte order in unsigned short value. </td>
917
    </tr>
918
    <tr>
919
      <td class="kt" nowrap="nowrap">sint32_t __REVSH (sint16_t value)</td>
920
      <td class="kt">M0, M3</td>
921
      <td class="kt">REVSH</td>
922
      <td class="kt">Reverse byte order in signed short value with sign extension to integer.</td>
923
    </tr>
924
    <tr>
925
      <td class="kt" nowrap="nowrap">uint32_t __RBIT (uint32_t value)</td>
926
      <td class="kt">M3</td>
927
      <td class="kt">RBIT</td>
928
      <td class="kt">Reverse bit order of value</td>
929
    </tr>
930
    <tr>
931
      <td class="kt" nowrap="nowrap">uint8_t __LDREXB (uint8_t *addr)</td>
932
      <td class="kt">M3</td>
933
      <td class="kt">LDREXB</td>
934
      <td class="kt">Load exclusive byte</td>
935
    </tr>
936
    <tr>
937
      <td class="kt" nowrap="nowrap">uint16_t __LDREXH (uint16_t *addr)</td>
938
      <td class="kt">M3</td>
939
      <td class="kt">LDREXH</td>
940
      <td class="kt">Load exclusive half-word</td>
941
    </tr>
942
    <tr>
943
      <td class="kt" nowrap="nowrap">uint32_t __LDREXW (uint32_t *addr)</td>
944
      <td class="kt">M3</td>
945
      <td class="kt">LDREXW</td>
946
      <td class="kt">Load exclusive word</td>
947
    </tr>
948
    <tr>
949
      <td class="kt" nowrap="nowrap">uint32_t __STREXB (uint8_t value, uint8_t *addr)</td>
950
      <td class="kt">M3</td>
951
      <td class="kt">STREXB</td>
952
      <td class="kt">Store exclusive byte</td>
953
    </tr>
954
    <tr>
955
      <td class="kt" nowrap="nowrap">uint32_t __STREXB (uint16_t value, uint16_t *addr)</td>
956
      <td class="kt">M3</td>
957
      <td class="kt">STREXH</td>
958
      <td class="kt">Store exclusive half-word</td>
959
    </tr>
960
    <tr>
961
      <td class="kt" nowrap="nowrap">uint32_t __STREXB (uint32_t value, uint32_t *addr)</td>
962
      <td class="kt">M3</td>
963
      <td class="kt">STREXW</td>
964
      <td class="kt">Store exclusive word</td>
965
    </tr>
966
    <tr>
967
      <td class="kt" nowrap="nowrap">void  __CLREX (void)</td>
968
      <td class="kt">M3</td>
969
      <td class="kt">CLREX</td>
970
      <td class="kt">Remove the exclusive lock created by __LDREXB, __LDREXH, or __LDREXW</td>
971
    </tr>
972
  </tbody>
973
</table>
974
 
975
 
976
<h3>NVIC Access Functions</h3>
977
<p>
978
  The CMSIS provides access to the NVIC via the register interface structure and several helper
979
  functions that simplify the setup of the NVIC. The CMSIS HAL uses IRQ numbers (IRQn) to
980
  identify the interrupts. The first device interrupt has the IRQn value 0. Therefore negative
981
  IRQn values are used for processor core exceptions.
982
</p>
983
<p>
984
  For the IRQn values of core exceptions the file <strong><em>device.h</em></strong> provides
985
  the following enum names.
986
</p>
987
 
988
<table class="kt" border="0" cellpadding="0" cellspacing="0">
989
  <tbody>
990
    <tr>
991
      <th class="kt" nowrap="nowrap">Core Exception enum Value</th>
992
      <th class="kt">Core</th>
993
      <th class="kt">IRQn</th>
994
      <th class="kt">Description</th>
995
    </tr>
996
    <tr>
997
      <td class="kt" nowrap="nowrap">NonMaskableInt_IRQn</td>
998
      <td class="kt">M0, M3</td>
999
      <td class="kt">-14</td>
1000
      <td class="kt">Cortex-M Non Maskable Interrupt</td>
1001
    </tr>
1002
    <tr>
1003
      <td class="kt" nowrap="nowrap">HardFault_IRQn</td>
1004
      <td class="kt">M0, M3</td>
1005
      <td class="kt">-13</td>
1006
      <td class="kt">Cortex-M Hard Fault Interrupt</td>
1007
    </tr>
1008
    <tr>
1009
      <td class="kt" nowrap="nowrap">MemoryManagement_IRQn</td>
1010
      <td class="kt">M3</td>
1011
      <td class="kt">-12</td>
1012
      <td class="kt">Cortex-M Memory Management Interrupt</td>
1013
    </tr>
1014
    <tr>
1015
      <td class="kt" nowrap="nowrap">BusFault_IRQn</td>
1016
      <td class="kt">M3</td>
1017
      <td class="kt">-11</td>
1018
      <td class="kt">Cortex-M Bus Fault Interrupt</td>
1019
    </tr>
1020
    <tr>
1021
      <td class="kt" nowrap="nowrap">UsageFault_IRQn</td>
1022
      <td class="kt">M3</td>
1023
      <td class="kt">-10</td>
1024
      <td class="kt">Cortex-M Usage Fault Interrupt</td>
1025
    </tr>
1026
    <tr>
1027
      <td class="kt" nowrap="nowrap">SVCall_IRQn</td>
1028
      <td class="kt">M0, M3</td>
1029
      <td class="kt">-5</td>
1030
      <td class="kt">Cortex-M SV Call Interrupt </td>
1031
    </tr>
1032
    <tr>
1033
      <td class="kt" nowrap="nowrap">DebugMonitor_IRQn</td>
1034
      <td class="kt">M3</td>
1035
      <td class="kt">-4</td>
1036
      <td class="kt">Cortex-M Debug Monitor Interrupt</td>
1037
    </tr>
1038
    <tr>
1039
      <td class="kt" nowrap="nowrap">PendSV_IRQn</td>
1040
      <td class="kt">M0, M3</td>
1041
      <td class="kt">-2</td>
1042
      <td class="kt">Cortex-M Pend SV Interrupt</td>
1043
    </tr>
1044
    <tr>
1045
      <td class="kt" nowrap="nowrap">SysTick_IRQn</td>
1046
      <td class="kt">M0, M3</td>
1047
      <td class="kt">-1</td>
1048
      <td class="kt">Cortex-M System Tick Interrupt</td>
1049
    </tr>
1050
  </tbody>
1051
</table>
1052
 
1053
<p>The following functions simplify the setup of the NVIC.
1054
The functions are defined as <strong>static inline</strong>.</p>
1055
 
1056
<table class="kt" border="0" cellpadding="0" cellspacing="0">
1057
  <tbody>
1058
    <tr>
1059
      <th class="kt" nowrap="nowrap">Name</th>
1060
      <th class="kt">Core</th>
1061
      <th class="kt">Parameter</th>
1062
      <th class="kt">Description</th>
1063
    </tr>
1064
    <tr>
1065
      <td class="kt" nowrap="nowrap">void NVIC_SetPriorityGrouping (uint32_t PriorityGroup)</td>
1066
      <td class="kt">M3</td>
1067
      <td class="kt">Priority Grouping Value</td>
1068
      <td class="kt">Set the Priority Grouping (Groups . Subgroups)</td>
1069
    </tr>
1070
    <tr>
1071
      <td class="kt" nowrap="nowrap">uint32_t NVIC_GetPriorityGrouping (void)</td>
1072
      <td class="kt">M3</td>
1073
      <td class="kt">(void)</td>
1074
      <td class="kt">Get the Priority Grouping (Groups . Subgroups)</td>
1075
    </tr>
1076
    <tr>
1077
      <td class="kt" nowrap="nowrap">void NVIC_EnableIRQ (IRQn_Type IRQn)</td>
1078
      <td class="kt">M0, M3</td>
1079
      <td class="kt">IRQ Number</td>
1080
      <td class="kt">Enable IRQn</td>
1081
    </tr>
1082
    <tr>
1083
      <td class="kt" nowrap="nowrap">void NVIC_DisableIRQ (IRQn_Type IRQn)</td>
1084
      <td class="kt">M0, M3</td>
1085
      <td class="kt">IRQ Number</td>
1086
      <td class="kt">Disable IRQn</td>
1087
    </tr>
1088
    <tr>
1089
      <td class="kt" nowrap="nowrap">uint32_t NVIC_GetPendingIRQ (IRQn_Type IRQn)</td>
1090
      <td class="kt">M0, M3</td>
1091
      <td class="kt">IRQ Number</td>
1092
      <td class="kt">Return 1 if IRQn is pending else 0</td>
1093
    </tr>
1094
    <tr>
1095
      <td class="kt" nowrap="nowrap">void NVIC_SetPendingIRQ (IRQn_Type IRQn)</td>
1096
      <td class="kt">M0, M3</td>
1097
      <td class="kt">IRQ Number</td>
1098
      <td class="kt">Set IRQn Pending</td>
1099
    </tr>
1100
    <tr>
1101
      <td class="kt" nowrap="nowrap">void NVIC_ClearPendingIRQ (IRQn_Type IRQn)</td>
1102
      <td class="kt">M0, M3</td>
1103
      <td class="kt">IRQ Number</td>
1104
      <td class="kt">Clear IRQn Pending Status</td>
1105
    </tr>
1106
    <tr>
1107
      <td class="kt" nowrap="nowrap">uint32_t NVIC_GetActive (IRQn_Type IRQn)</td>
1108
      <td class="kt">M3</td>
1109
      <td class="kt">IRQ Number</td>
1110
      <td class="kt">Return 1 if IRQn is active else 0</td>
1111
    </tr>
1112
    <tr>
1113
      <td class="kt" nowrap="nowrap">void NVIC_SetPriority (IRQn_Type IRQn, uint32_t priority)</td>
1114
      <td class="kt">M0, M3</td>
1115
      <td class="kt">IRQ Number, Priority</td>
1116
      <td class="kt">Set Priority for IRQn<br>
1117
                     (not threadsafe for Cortex-M0)</td>
1118
    </tr>
1119
    <tr>
1120
      <td class="kt" nowrap="nowrap">uint32_t NVIC_GetPriority (IRQn_Type IRQn)</td>
1121
      <td class="kt">M0, M3</td>
1122
      <td class="kt">IRQ Number</td>
1123
      <td class="kt">Get Priority for IRQn</td>
1124
    </tr>
1125
    <tr>
1126
<!--      <td class="kt" nowrap="nowrap">uint32_t NVIC_EncodePriority (uint32_t PriorityGroup, uint32_t PreemptPriority, uint32_t SubPriority)</td> -->
1127
      <td class="kt">uint32_t NVIC_EncodePriority (uint32_t PriorityGroup, uint32_t PreemptPriority, uint32_t SubPriority)</td>
1128
      <td class="kt">M3</td>
1129
      <td class="kt">IRQ Number, Priority Group, Preemptive Priority, Sub Priority</td>
1130
      <td class="kt">Encode priority for given group, preemptive and sub priority</td>
1131
    </tr>
1132
<!--      <td class="kt" nowrap="nowrap">NVIC_DecodePriority (uint32_t Priority, uint32_t PriorityGroup, uint32_t* pPreemptPriority, uint32_t* pSubPriority)</td> -->
1133
      <td class="kt">NVIC_DecodePriority (uint32_t Priority, uint32_t PriorityGroup, uint32_t* pPreemptPriority, uint32_t* pSubPriority)</td>
1134
      <td class="kt">M3</td>
1135
      <td class="kt">IRQ Number, Priority, pointer to Priority Group, pointer to Preemptive Priority, pointer to Sub Priority</td>
1136
      <td class="kt">Deccode given priority to group, preemptive and sub priority</td>
1137
    </tr>
1138
    <tr>
1139
      <td class="kt" nowrap="nowrap">void NVIC_SystemReset (void)</td>
1140
      <td class="kt">M0, M3</td>
1141
      <td class="kt">(void)</td>
1142
      <td class="kt">Resets the System</td>
1143
    </tr>
1144
  </tbody>
1145
</table>
1146
<p class="Note">Note</p>
1147
<ul>
1148
  <li><p>The processor exceptions have negative enum values. Device specific interrupts
1149
               have positive enum values and start with 0. The values are defined in
1150
         <b><em>device.h</em></b> file.
1151
      </p>
1152
  </li>
1153
  <li><p>The values for <b>PreemptPriority</b> and <b>SubPriority</b>
1154
         used in functions <b>NVIC_EncodePriority</b> and <b>NVIC_DecodePriority</b>
1155
         depend on the available __NVIC_PRIO_BITS implemented in the NVIC.
1156
      </p>
1157
  </li>
1158
</ul>
1159
 
1160
 
1161
<h3>SysTick Configuration Function</h3>
1162
 
1163
<p>The following function is used to configure the SysTick timer and start the
1164
SysTick interrupt.</p>
1165
 
1166
<table class="kt" border="0" cellpadding="0" cellspacing="0">
1167
  <tbody>
1168
    <tr>
1169
      <th class="kt" nowrap="nowrap">Name</th>
1170
      <th class="kt">Parameter</th>
1171
      <th class="kt">Description</th>
1172
    </tr>
1173
    <tr>
1174
      <td class="kt" nowrap="nowrap">uint32_t Sys<span class="style1">TickConfig
1175
                (uint32_t ticks)</span></td>
1176
      <td class="kt">ticks is SysTick counter reload value</td>
1177
      <td class="kt">Setup the SysTick timer and enable the SysTick interrupt. After this
1178
                call the SysTick timer creates interrupts with the specified time
1179
                interval. <br>
1180
                <br>
1181
                Return: 0 when successful, 1 on failure.<br>
1182
                </td>
1183
    </tr>
1184
  </tbody>
1185
</table>
1186
 
1187
 
1188
<h3>Cortex-M3 ITM Debug Access</h3>
1189
 
1190
<p>The Cortex-M3 incorporates the Instrumented Trace Macrocell (ITM) that
1191
provides together with the Serial Viewer Output trace capabilities for the
1192
microcontroller system. The ITM has 32 communication channels; two ITM
1193
communication channels are used by CMSIS to output the following information:</p>
1194
<ul>
1195
        <li>ITM Channel 0: implements the <strong>ITM_SendChar</strong> function
1196
        which can be used for printf-style output via the debug interface.</li>
1197
        <li>ITM Channel 31: is reserved for the RTOS kernel and can be used for
1198
        kernel awareness debugging.</li>
1199
</ul>
1200
<p class="Note">Note</p>
1201
<ul>
1202
  <li><p>The ITM channel 31 is selected for the RTOS kernel since some kernels
1203
        may use the Privileged level for program execution. ITM
1204
        channels have 4 groups with 8 channels each, whereby each group can be
1205
        configured for access rights in the Unprivileged level. The ITM channel 0
1206
        may be therefore enabled for the user task whereas ITM channel 31 may be
1207
        accessible only in Privileged level from the RTOS kernel itself.</p>
1208
  </li>
1209
</ul>
1210
 
1211
<p>The prototype of the <strong>ITM_SendChar</strong> routine is shown in the
1212
table below.</p>
1213
 
1214
<table class="kt" border="0" cellpadding="0" cellspacing="0">
1215
  <tbody>
1216
    <tr>
1217
      <th class="kt" nowrap="nowrap">Name</th>
1218
      <th class="kt">Parameter</th>
1219
      <th class="kt">Description</th>
1220
    </tr>
1221
    <tr>
1222
      <td class="kt" nowrap="nowrap">void uint32_t ITM_SendChar(uint32_t chr)</td>
1223
      <td class="kt">character to output</td>
1224
      <td class="kt">The function outputs a character via the ITM channel 0. The
1225
                                 function returns when no debugger is connected that has booked the
1226
                                 output. It is blocking when a debugger is connected, but the
1227
                                 previous character send is not transmitted. <br><br>
1228
                                 Return: the input character 'chr'.</td>
1229
    </tr>
1230
  </tbody>
1231
</table>
1232
 
1233
<p>
1234
  Example for the usage of the ITM Channel 31 for RTOS Kernels:
1235
</p>
1236
<pre>
1237
  // check if debugger connected and ITM channel enabled for tracing
1238
  if ((CoreDebug-&gt;DEMCR &amp; CoreDebug_DEMCR_TRCENA) &amp;&amp;
1239
  (ITM-&gt;TCR &amp; ITM_TCR_ITMENA) &amp;&amp;
1240
  (ITM-&gt;TER &amp; (1UL &lt;&lt; 31))) {
1241
    // transmit trace data
1242
    while (ITM-&gt;PORT31_U32 == 0);
1243
    ITM-&gt;PORT[31].u8 = task_id;      // id of next task
1244
    while (ITM-&gt;PORT[31].u32 == 0);
1245
    ITM-&gt;PORT[31].u32 = task_status; // status information
1246
  }</pre>
1247
 
1248
 
1249
<h3>Cortex-M3 additional Debug Access</h3>
1250
 
1251
<p>CMSIS provides additional debug functions to enlarge the Cortex-M3 Debug Access.
1252
Data can be transmitted via a certain global buffer variable towards the target system.</p>
1253
 
1254
<p>The buffer variable and the prototypes of the additional functions are shown in the
1255
table below.</p>
1256
 
1257
<table class="kt" border="0" cellpadding="0" cellspacing="0">
1258
  <tbody>
1259
    <tr>
1260
      <th class="kt" nowrap="nowrap">Name</th>
1261
      <th class="kt">Parameter</th>
1262
      <th class="kt">Description</th>
1263
    </tr>
1264
    <tr>
1265
      <td class="kt" nowrap="nowrap">extern volatile int ITM_RxBuffer</td>
1266
      <td class="kt"> </td>
1267
      <td class="kt">Buffer to transmit data towards debug system. <br><br>
1268
                                 Value 0x5AA55AA5 indicates that buffer is empty.</td>
1269
    </tr>
1270
    <tr>
1271
      <td class="kt" nowrap="nowrap">int ITM_ReceiveChar (void)</td>
1272
      <td class="kt">none</td>
1273
      <td class="kt">The nonblocking functions returns the character stored in
1274
                     ITM_RxBuffer. <br><br>
1275
                                 Return: -1 indicates that no character was received.</td>
1276
    </tr>
1277
    <tr>
1278
      <td class="kt" nowrap="nowrap">int ITM_CheckChar (void)</td>
1279
      <td class="kt">none</td>
1280
      <td class="kt">The function checks if a character is available in ITM_RxBuffer. <br><br>
1281
                                 Return: 1 indicates that a character is available, 0 indicates that
1282
                     no character is available.</td>
1283
    </tr>
1284
  </tbody>
1285
</table>
1286
 
1287
 
1288
<h2><a name="5"></a>CMSIS Example</h2>
1289
<p>
1290
  The following section shows a typical example for using the CMSIS layer in user applications.
1291
  The example is based on a STM32F10x Device.
1292
</p>
1293
<pre>
1294
#include "stm32f10x.h"
1295
 
1296
volatile uint32_t msTicks;                       /* timeTicks counter */
1297
 
1298
void SysTick_Handler(void) {
1299
  msTicks++;                                     /* increment timeTicks counter */
1300
}
1301
 
1302
__INLINE static void Delay (uint32_t dlyTicks) {
1303
  uint32_t curTicks = msTicks;
1304
 
1305
  while ((msTicks - curTicks) &lt; dlyTicks);
1306
}
1307
 
1308
__INLINE static void LED_Config(void) {
1309
  ;                                              /* Configure the LEDs */
1310
}
1311
 
1312
__INLINE static void LED_On (uint32_t led) {
1313
  ;                                              /* Turn On  LED */
1314
}
1315
 
1316
__INLINE static void LED_Off (uint32_t led) {
1317
  ;                                              /* Turn Off LED */
1318
}
1319
 
1320
int main (void) {
1321
  if (SysTick_Config (SystemCoreClock / 1000)) { /* Setup SysTick for 1 msec interrupts */
1322
    ;                                            /* Handle Error */
1323
    while (1);
1324
  }
1325
 
1326
  LED_Config();                                  /* configure the LEDs */
1327
 
1328
  while(1) {
1329
    LED_On (0x100);                              /* Turn  on the LED   */
1330
    Delay (100);                                 /* delay  100 Msec    */
1331
    LED_Off (0x100);                             /* Turn off the LED   */
1332
    Delay (100);                                 /* delay  100 Msec    */
1333
  }
1334
}</pre>
1335
 
1336
 
1337
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