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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/host/Source/CMSIS/Documentation/CMSIS_Core.htm Wed Feb 03 10:44:42 2016 +0300 @@ -0,0 +1,1337 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<html xmlns:p="urn:schemas-microsoft-com:office:powerpoint" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office"><head> + + <title>CMSIS: Cortex Microcontroller Software Interface Standard</title><meta http-equiv="Content-Type" content="text/html; charset=windows-1252"> + <meta name="ProgId" content="FrontPage.Editor.Document"> + <style> +<!-- +/*-----------------------------------------------------------Keil Software CHM Style Sheet +-----------------------------------------------------------*/ +body { color: #000000; background-color: #FFFFFF; font-size: 75%; font-family: Verdana, Arial, 'Sans Serif' } +a:link { color: #0000FF; text-decoration: underline } +a:visited { color: #0000FF; text-decoration: underline } +a:active { color: #FF0000; text-decoration: underline } +a:hover { color: #FF0000; text-decoration: underline } +h1 { font-family: Verdana; font-size: 18pt; color: #000080; font-weight: bold; text-align: Center; margin-right: 3 } +h2 { font-family: Verdana; font-size: 14pt; color: #000080; font-weight: bold; background-color: #CCCCCC; margin-top: 24; margin-bottom: 3; padding: 6 } +h3 { font-family: Verdana; font-size: 10pt; font-weight: bold; background-color: #CCCCCC; margin-top: 24; margin-bottom: 3; padding: 6 } +pre { font-family: Courier New; font-size: 10pt; background-color: #CCFFCC; margin-left: 24; margin-right: 24 } +ul { list-style-type: square; margin-top: 6pt; margin-bottom: 0 } +ol { margin-top: 6pt; margin-bottom: 0 } +li { clear: both; margin-bottom: 6pt } +table { font-size: 100%; border-width: 0; padding: 0 } +th { color: #FFFFFF; background-color: #000080; text-align: left; vertical-align: bottom; padding-right: 6pt } +tr { text-align: left; vertical-align: top } +td { text-align: left; vertical-align: top; padding-right: 6pt } +.ToolT { font-size: 8pt; color: #808080 } +.TinyT { font-size: 8pt; text-align: Center } +code { color: #000000; background-color: #E0E0E0; font-family: 'Courier New', Courier; line-height: 120%; font-style: normal } +/*-----------------------------------------------------------Notes +-----------------------------------------------------------*/ +p.note { font-weight: bold; clear: both; margin-bottom: 3pt; padding-top: 6pt } +/*-----------------------------------------------------------Expanding/Contracting Divisions +-----------------------------------------------------------*/ +#expand { text-decoration: none; margin-bottom: 3pt } +img.expand { border-style: none; border-width: medium } +div.expand { display: none; margin-left: 9pt; margin-top: 0 } +/*-----------------------------------------------------------Where List Tags +-----------------------------------------------------------*/ +p.wh { font-weight: bold; clear: both; margin-top: 6pt; margin-bottom: 3pt } +table.wh { width: 100% } +td.whItem { white-space: nowrap; font-style: italic; padding-right: 6pt; padding-bottom: 6pt } +td.whDesc { padding-bottom: 6pt } +/*-----------------------------------------------------------Keil Table Tags +-----------------------------------------------------------*/ +table.kt { width: 100%; border: 1pt solid #000000 } +th.kt { white-space: nowrap; border-bottom: 1pt solid #000000; padding-left: 6pt; padding-right: 6pt; padding-top: 4pt; padding-bottom: 4pt } +tr.kt { } +td.kt { color: #000000; background-color: #E0E0E0; border-top: 1pt solid #A0A0A0; padding-left: 6pt; padding-right: 6pt; padding-top: 2pt; padding-bottom: 2pt } +/*----------------------------------------------------------------------------------------------------------------------*/ + .style1 { + background-color: #E0E0E0; +} +.O + {color:#1D315B; + font-size:149%;} + --> + </style></head> +<body> +<h1>Cortex Microcontroller Software Interface Standard</h1> + +<p align="center">This file describes the Cortex Microcontroller Software Interface Standard (CMSIS).</p> +<p align="center">Version: 1.30 - 30. October 2009</p> + +<p class="TinyT">Information in this file, the accompany manuals, and software is<br> + Copyright © ARM Ltd.<br>All rights reserved. +</p> + +<hr> + +<p><span style="FONT-WEIGHT: bold">Revision History</span></p> +<ul> + <li>Version 1.00: initial release. </li> + <li>Version 1.01: added __LDREX<em>x</em>, __STREX<em>x</em>, and __CLREX.</li> + <li>Version 1.02: added Cortex-M0. </li> + <li>Version 1.10: second review. </li> + <li>Version 1.20: third review. </li> + <li>Version 1.30 PRE-RELEASE: reworked Startup Concept, additional Debug Functionality.</li> + <li>Version 1.30 2nd PRE-RELEASE: changed folder structure, added doxyGen comments, added Bit definitions.</li> + <li>Version 1.30: updated Device Support Packages.</li> +</ul> + +<hr> + +<h2>Contents</h2> + +<ol> + <li class="LI2"><a href="#1">About</a></li> + <li class="LI2"><a href="#2">Coding Rules and Conventions</a></li> + <li class="LI2"><a href="#3">CMSIS Files</a></li> + <li class="LI2"><a href="#4">Core Peripheral Access Layer</a></li> + <li class="LI2"><a href="#5">CMSIS Example</a></li> +</ol> + +<h2><a name="1"></a>About</h2> + +<p> + The <strong>Cortex Microcontroller Software Interface Standard (CMSIS)</strong> answers the challenges + that are faced when software components are deployed to physical microcontroller devices based on a + Cortex-M0 or Cortex-M3 processor. The CMSIS will be also expanded to future Cortex-M + processor cores (the term Cortex-M is used to indicate that). The CMSIS is defined in close co-operation + with various silicon and software vendors and provides a common approach to interface to peripherals, + real-time operating systems, and middleware components. +</p> + +<p>ARM provides as part of the CMSIS the following software layers that are +available for various compiler implementations:</p> +<ul> + <li><strong>Core Peripheral Access Layer</strong>: contains name definitions, + address definitions and helper functions to + access core registers and peripherals. It defines also a device + independent interface for RTOS Kernels that includes debug channel + definitions.</li> +</ul> + +<p>These software layers are expanded by Silicon partners with:</p> +<ul> + <li><strong>Device Peripheral Access Layer</strong>: provides definitions + for all device peripherals</li> + <li><strong>Access Functions for Peripherals (optional)</strong>: provides + additional helper functions for peripherals</li> +</ul> + +<p>CMSIS defines for a Cortex-M Microcontroller System:</p> +<ul> + <li style="text-align: left;">A common way to access peripheral registers + and a common way to define exception vectors.</li> + <li style="text-align: left;">The register names of the <strong>Core + Peripherals</strong> and<strong> </strong>the names of the <strong>Core + Exception Vectors</strong>.</li> + <li>An device independent interface for RTOS Kernels including a debug + channel.</li> +</ul> + +<p> + By using CMSIS compliant software components, the user can easier re-use template code. + CMSIS is intended to enable the combination of software components from multiple middleware vendors. +</p> + +<h2><a name="2"></a>Coding Rules and Conventions</h2> + +<p> + The following section describes the coding rules and conventions used in the CMSIS + implementation. It contains also information about data types and version number information. +</p> + +<h3>Essentials</h3> +<ul> + <li>The CMSIS C code conforms to MISRA 2004 rules. In case of MISRA violations, + there are disable and enable sequences for PC-LINT inserted.</li> + <li>ANSI standard data types defined in the ANSI C header file + <strong><stdint.h></strong> are used.</li> + <li>#define constants that include expressions must be enclosed by + parenthesis.</li> + <li>Variables and parameters have a complete data type.</li> + <li>All functions in the <strong>Core Peripheral Access Layer</strong> are + re-entrant.</li> + <li>The <strong>Core Peripheral Access Layer</strong> has no blocking code + (which means that wait/query loops are done at other software layers).</li> + <li>For each exception/interrupt there is definition for: + <ul> + <li>an exception/interrupt handler with the postfix <strong>_Handler </strong> + (for exceptions) or <strong>_IRQHandler</strong> (for interrupts).</li> + <li>a default exception/interrupt handler (weak definition) that contains an endless loop.</li> + <li>a #define of the interrupt number with the postfix <strong>_IRQn</strong>.</li> + </ul></li> +</ul> + +<h3>Recommendations</h3> + +<p>The CMSIS recommends the following conventions for identifiers.</p> +<ul> + <li><strong>CAPITAL</strong> names to identify Core Registers, Peripheral Registers, and CPU Instructions.</li> + <li><strong>CamelCase</strong> names to identify peripherals access functions and interrupts.</li> + <li><strong>PERIPHERAL_</strong> prefix to identify functions that belong to specify peripherals.</li> + <li><strong>Doxygen</strong> comments for all functions are included as described under <strong>Function Comments</strong> below.</li> +</ul> + +<b>Comments</b> + +<ul> + <li>Comments use the ANSI C90 style (<em>/* comment */</em>) or C++ style + (<em>// comment</em>). It is assumed that the programming tools support today + consistently the C++ comment style.</li> + <li><strong>Function Comments</strong> provide for each function the following information: + <ul> + <li>one-line brief function overview.</li> + <li>detailed parameter explanation.</li> + <li>detailed information about return values.</li> + <li>detailed description of the actual function.</li> + </ul> + <p><b>Doxygen Example:</b></p> + <pre> +/** + * @brief Enable Interrupt in NVIC Interrupt Controller + * @param IRQn interrupt number that specifies the interrupt + * @return none. + * Enable the specified interrupt in the NVIC Interrupt Controller. + * Other settings of the interrupt such as priority are not affected. + */</pre> + </li> +</ul> + +<h3>Data Types and IO Type Qualifiers</h3> + +<p> + The <strong>Cortex-M HAL</strong> uses the standard types from the standard ANSI C header file + <strong><stdint.h></strong>. <strong>IO Type Qualifiers</strong> are used to specify the access + to peripheral variables. IO Type Qualifiers are indented to be used for automatic generation of + debug information of peripheral registers. +</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt" nowrap="nowrap">IO Type Qualifier</th> + <th class="kt">#define</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">__I</td> + <td class="kt">volatile const</td> + <td class="kt">Read access only</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">__O</td> + <td class="kt">volatile</td> + <td class="kt">Write access only</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">__IO</td> + <td class="kt">volatile</td> + <td class="kt">Read and write access</td> + </tr> + </tbody> +</table> + +<h3>CMSIS Version Number</h3> +<p> + File <strong>core_cm3.h</strong> contains the version number of the CMSIS with the following define: +</p> + +<pre> +#define __CM3_CMSIS_VERSION_MAIN (0x01) /* [31:16] main version */ +#define __CM3_CMSIS_VERSION_SUB (0x30) /* [15:0] sub version */ +#define __CM3_CMSIS_VERSION ((__CM3_CMSIS_VERSION_MAIN << 16) | __CM3_CMSIS_VERSION_SUB)</pre> + +<p> + File <strong>core_cm0.h</strong> contains the version number of the CMSIS with the following define: +</p> + +<pre> +#define __CM0_CMSIS_VERSION_MAIN (0x01) /* [31:16] main version */ +#define __CM0_CMSIS_VERSION_SUB (0x30) /* [15:0] sub version */ +#define __CM0_CMSIS_VERSION ((__CM0_CMSIS_VERSION_MAIN << 16) | __CM0_CMSIS_VERSION_SUB)</pre> + + +<h3>CMSIS Cortex Core</h3> +<p> + File <strong>core_cm3.h</strong> contains the type of the CMSIS Cortex-M with the following define: +</p> + +<pre> +#define __CORTEX_M (0x03)</pre> + +<p> + File <strong>core_cm0.h</strong> contains the type of the CMSIS Cortex-M with the following define: +</p> + +<pre> +#define __CORTEX_M (0x00)</pre> + + +<h2><a name="3"></a>CMSIS Files</h2> +<p> + This section describes the Files provided in context with the CMSIS to access the Cortex-M + hardware and peripherals. +</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt" nowrap="nowrap">File</th> + <th class="kt">Provider</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap"><i>device.h</i></td> + <td class="kt">Device specific (provided by silicon partner)</td> + <td class="kt">Defines the peripherals for the actual device. The file may use + several other include files to define the peripherals of the actual device.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">core_cm0.h</td> + <td class="kt">ARM (for RealView ARMCC, IAR, and GNU GCC)</td> + <td class="kt">Defines the core peripherals for the Cortex-M0 CPU and core peripherals.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">core_cm3.h</td> + <td class="kt">ARM (for RealView ARMCC, IAR, and GNU GCC)</td> + <td class="kt">Defines the core peripherals for the Cortex-M3 CPU and core peripherals.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">core_cm0.c</td> + <td class="kt">ARM (for RealView ARMCC, IAR, and GNU GCC)</td> + <td class="kt">Provides helper functions that access core registers.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">core_cm3.c</td> + <td class="kt">ARM (for RealView ARMCC, IAR, and GNU GCC)</td> + <td class="kt">Provides helper functions that access core registers.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">startup<i>_device</i></td> + <td class="kt">ARM (adapted by compiler partner / silicon partner)</td> + <td class="kt">Provides the Cortex-M startup code and the complete (device specific) Interrupt Vector Table</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">system<i>_device</i></td> + <td class="kt">ARM (adapted by silicon partner)</td> + <td class="kt">Provides a device specific configuration file for the device. It configures the device initializes + typically the oscillator (PLL) that is part of the microcontroller device</td> + </tr> + </tbody> +</table> + +<h3><em>device.h</em></h3> + +<p> + The file <em><strong>device.h</strong></em> is provided by the silicon vendor and is the + <u><strong>central include file</strong></u> that the application programmer is using in + the C source code. This file contains: +</p> +<ul> + <li> + <p><strong>Interrupt Number Definition</strong>: provides interrupt numbers + (IRQn) for all core and device specific exceptions and interrupts.</p> + </li> + <li> + <p><strong>Configuration for core_cm0.h / core_cm3.h</strong>: reflects the + actual configuration of the Cortex-M processor that is part of the actual + device. As such the file <strong>core_cm0.h / core_cm3.h</strong> is included that + implements access to processor registers and core peripherals. </p> + </li> + <li> + <p><strong>Device Peripheral Access Layer</strong>: provides definitions + for all device peripherals. It contains all data structures and the address + mapping for the device specific peripherals. </p> + </li> + <li><strong>Access Functions for Peripherals (optional)</strong>: provides + additional helper functions for peripherals that are useful for programming + of these peripherals. Access Functions may be provided as inline functions + or can be extern references to a device specific library provided by the + silicon vendor.</li> +</ul> + + +<h4><strong>Interrupt Number Definition</strong></h4> + +<p>To access the device specific interrupts the device.h file defines IRQn +numbers for the complete device using a enum typedef as shown below:</p> +<pre> +typedef enum IRQn +{ +/****** Cortex-M3 Processor Exceptions/Interrupt Numbers ************************************************/ + NonMaskableInt_IRQn = -14, /*!< 2 Non Maskable Interrupt */ + HardFault_IRQn = -13, /*!< 3 Cortex-M3 Hard Fault Interrupt */ + MemoryManagement_IRQn = -12, /*!< 4 Cortex-M3 Memory Management Interrupt */ + BusFault_IRQn = -11, /*!< 5 Cortex-M3 Bus Fault Interrupt */ + UsageFault_IRQn = -10, /*!< 6 Cortex-M3 Usage Fault Interrupt */ + SVCall_IRQn = -5, /*!< 11 Cortex-M3 SV Call Interrupt */ + DebugMonitor_IRQn = -4, /*!< 12 Cortex-M3 Debug Monitor Interrupt */ + PendSV_IRQn = -2, /*!< 14 Cortex-M3 Pend SV Interrupt */ + SysTick_IRQn = -1, /*!< 15 Cortex-M3 System Tick Interrupt */ +/****** STM32 specific Interrupt Numbers ****************************************************************/ + WWDG_STM_IRQn = 0, /*!< Window WatchDog Interrupt */ + PVD_STM_IRQn = 1, /*!< PVD through EXTI Line detection Interrupt */ + : + : + } IRQn_Type;</pre> + + +<h4>Configuration for core_cm0.h / core_cm3.h</h4> +<p> + The Cortex-M core configuration options which are defined for each device implementation. Some + configuration options are reflected in the CMSIS layer using the #define settings described below. +</p> +<p> + To access core peripherals file <em><strong>device.h</strong></em> includes file <b>core_cm0.h / core_cm3.h</b>. + Several features in <strong>core_cm0.h / core_cm3.h</strong> are configured by the following defines that must be + defined before <strong>#include <core_cm0.h></strong> / <strong>#include <core_cm3.h></strong> + preprocessor command. +</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt" nowrap="nowrap">#define</th> + <th class="kt" nowrap="nowrap">File</th> + <th class="kt" nowrap="nowrap">Value</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">__NVIC_PRIO_BITS</td> + <td class="kt">core_cm0.h</td> + <td class="kt" nowrap="nowrap">(2)</td> + <td class="kt">Number of priority bits implemented in the NVIC (device specific)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">__NVIC_PRIO_BITS</td> + <td class="kt">core_cm3.h</td> + <td class="kt" nowrap="nowrap">(2 ... 8)</td> + <td class="kt">Number of priority bits implemented in the NVIC (device specific)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">__MPU_PRESENT</td> + <td class="kt">core_cm0.h, core_cm3.h</td> + <td class="kt" nowrap="nowrap">(0, 1)</td> + <td class="kt">Defines if an MPU is present or not</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">__Vendor_SysTickConfig</td> + <td class="kt">core_cm0.h, core_cm3.h</td> + <td class="kt" nowrap="nowrap">(1)</td> + <td class="kt">When this define is setup to 1, the <strong>SysTickConfig</strong> function + in <strong>core_cm3.h</strong> is excluded. In this case the <em><strong>device.h</strong></em> + file must contain a vendor specific implementation of this function.</td> + </tr> + </tbody> +</table> + + +<h4>Device Peripheral Access Layer</h4> +<p> + Each peripheral uses a prefix which consists of <strong><device abbreviation>_</strong> + and <strong><peripheral name>_</strong> to identify peripheral registers that access this + specific peripheral. The intention of this is to avoid name collisions caused + due to short names. If more than one peripheral of the same type exists, + identifiers have a postfix (digit or letter). For example: +</p> +<ul> + <li><device abbreviation>_UART_Type: defines the generic register layout for all UART channels in a device. + <pre> +typedef struct +{ + union { + __I uint8_t RBR; /*!< Offset: 0x000 Receiver Buffer Register */ + __O uint8_t THR; /*!< Offset: 0x000 Transmit Holding Register */ + __IO uint8_t DLL; /*!< Offset: 0x000 Divisor Latch LSB */ + uint32_t RESERVED0; + }; + union { + __IO uint8_t DLM; /*!< Offset: 0x004 Divisor Latch MSB */ + __IO uint32_t IER; /*!< Offset: 0x004 Interrupt Enable Register */ + }; + union { + __I uint32_t IIR; /*!< Offset: 0x008 Interrupt ID Register */ + __O uint8_t FCR; /*!< Offset: 0x008 FIFO Control Register */ + }; + __IO uint8_t LCR; /*!< Offset: 0x00C Line Control Register */ + uint8_t RESERVED1[7]; + __I uint8_t LSR; /*!< Offset: 0x014 Line Status Register */ + uint8_t RESERVED2[7]; + __IO uint8_t SCR; /*!< Offset: 0x01C Scratch Pad Register */ + uint8_t RESERVED3[3]; + __IO uint32_t ACR; /*!< Offset: 0x020 Autobaud Control Register */ + __IO uint8_t ICR; /*!< Offset: 0x024 IrDA Control Register */ + uint8_t RESERVED4[3]; + __IO uint8_t FDR; /*!< Offset: 0x028 Fractional Divider Register */ + uint8_t RESERVED5[7]; + __IO uint8_t TER; /*!< Offset: 0x030 Transmit Enable Register */ + uint8_t RESERVED6[39]; + __I uint8_t FIFOLVL; /*!< Offset: 0x058 FIFO Level Register */ +} LPC_UART_TypeDef;</pre> + </li> + <li><device abbreviation>_UART1: is a pointer to a register structure that refers to a specific UART. + For example UART1->DR is the data register of UART1. + <pre> +#define LPC_UART2 ((LPC_UART_TypeDef *) LPC_UART2_BASE ) +#define LPC_UART3 ((LPC_UART_TypeDef *) LPC_UART3_BASE )</pre> + </li> +</ul> + +<h5>Minimal Requiements</h5> +<p> + To access the peripheral registers and related function in a device the files <strong><em>device.h</em></strong> + and <strong>core_cm0.h</strong> / <strong>core_cm3.h</strong> defines as a minimum: +</p> +<ul> + <li>The <strong>Register Layout Typedef</strong> for each peripheral that defines all register names. + Names that start with RESERVE are used to introduce space into the structure to adjust the addresses of + the peripheral registers. For example: + <pre> +typedef struct { + __IO uint32_t CTRL; /* SysTick Control and Status Register */ + __IO uint32_t LOAD; /* SysTick Reload Value Register */ + __IO uint32_t VAL; /* SysTick Current Value Register */ + __I uint32_t CALIB; /* SysTick Calibration Register */ + } SysTick_Type;</pre> + </li> + + <li> + <strong>Base Address</strong> for each peripheral (in case of multiple peripherals + that use the same <strong>register layout typedef</strong> multiple base addresses are defined). For example: + <pre> +#define SysTick_BASE (SCS_BASE + 0x0010) /* SysTick Base Address */</pre> + </li> + + <li> + <strong>Access Definition</strong> for each peripheral (in case of multiple peripherals that use + the same <strong>register layout typedef</strong> multiple access definitions exist, i.e. LPC_UART0, + LPC_UART2). For Example: + <pre> +#define SysTick ((SysTick_Type *) SysTick_BASE) /* SysTick access definition */</pre> + </li> +</ul> + +<p> + These definitions allow to access the peripheral registers from user code with simple assignments like: +</p> +<pre>SysTick->CTRL = 0;</pre> + +<h5>Optional Features</h5> +<p>In addition the <em> <strong>device.h </strong></em>file may define:</p> +<ul> + <li> + #define constants that simplify access to the peripheral registers. + These constant define bit-positions or other specific patterns are that required for the + programming of the peripheral registers. The identifiers used start with + <strong><device abbreviation>_</strong> and <strong><peripheral name>_</strong>. + It is recommended to use CAPITAL letters for such #define constants. + </li> + <li> + Functions that perform more complex functions with the peripheral (i.e. status query before + a sending register is accessed). Again these function start with + <strong><device abbreviation>_</strong> and <strong><peripheral name>_</strong>. + </li> +</ul> + +<h3>core_cm0.h and core_cm0.c</h3> +<p> + File <b>core_cm0.h</b> describes the data structures for the Cortex-M0 core peripherals and does + the address mapping of this structures. It also provides basic access to the Cortex-M0 core registers + and core peripherals with efficient functions (defined as <strong>static inline</strong>). +</p> +<p> + File <b>core_cm0.c</b> defines several helper functions that access processor registers. +</p> +<p>Together these files implement the <a href="#4">Core Peripheral Access Layer</a> for a Cortex-M0.</p> + +<h3>core_cm3.h and core_cm3.c</h3> +<p> + File <b>core_cm3.h</b> describes the data structures for the Cortex-M3 core peripherals and does + the address mapping of this structures. It also provides basic access to the Cortex-M3 core registers + and core peripherals with efficient functions (defined as <strong>static inline</strong>). +</p> +<p> + File <b>core_cm3.c</b> defines several helper functions that access processor registers. +</p> +<p>Together these files implement the <a href="#4">Core Peripheral Access Layer</a> for a Cortex-M3.</p> + +<h3>startup_<em>device</em></h3> +<p> + A template file for <strong>startup_<em>device</em></strong> is provided by ARM for each supported + compiler. It is adapted by the silicon vendor to include interrupt vectors for all device specific + interrupt handlers. Each interrupt handler is defined as <strong><em>weak</em></strong> function + to an dummy handler. Therefore the interrupt handler can be directly used in application software + without any requirements to adapt the <strong>startup_<em>device</em></strong> file. +</p> +<p> + The following exception names are fixed and define the start of the vector table for a Cortex-M0: +</p> +<pre> +__Vectors DCD __initial_sp ; Top of Stack + DCD Reset_Handler ; Reset Handler + DCD NMI_Handler ; NMI Handler + DCD HardFault_Handler ; Hard Fault Handler + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD SVC_Handler ; SVCall Handler + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD PendSV_Handler ; PendSV Handler + DCD SysTick_Handler ; SysTick Handler</pre> + +<p> + The following exception names are fixed and define the start of the vector table for a Cortex-M3: +</p> +<pre> +__Vectors DCD __initial_sp ; Top of Stack + DCD Reset_Handler ; Reset Handler + DCD NMI_Handler ; NMI Handler + DCD HardFault_Handler ; Hard Fault Handler + DCD MemManage_Handler ; MPU Fault Handler + DCD BusFault_Handler ; Bus Fault Handler + DCD UsageFault_Handler ; Usage Fault Handler + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD 0 ; Reserved + DCD SVC_Handler ; SVCall Handler + DCD DebugMon_Handler ; Debug Monitor Handler + DCD 0 ; Reserved + DCD PendSV_Handler ; PendSV Handler + DCD SysTick_Handler ; SysTick Handler</pre> + +<p> + In the following examples for device specific interrupts are shown: +</p> +<pre> +; External Interrupts + DCD WWDG_IRQHandler ; Window Watchdog + DCD PVD_IRQHandler ; PVD through EXTI Line detect + DCD TAMPER_IRQHandler ; Tamper</pre> + +<p> + Device specific interrupts must have a dummy function that can be overwritten in user code. + Below is an example for this dummy function. +</p> +<pre> +Default_Handler PROC + EXPORT WWDG_IRQHandler [WEAK] + EXPORT PVD_IRQHandler [WEAK] + EXPORT TAMPER_IRQHandler [WEAK] + : + : + WWDG_IRQHandler + PVD_IRQHandler + TAMPER_IRQHandler + : + : + B . + ENDP</pre> + +<p> + The user application may simply define an interrupt handler function by using the handler name + as shown below. +</p> +<pre> +void WWDG_IRQHandler(void) +{ + : + : +}</pre> + + +<h3><a name="4"></a>system_<em>device</em>.c</h3> +<p> + A template file for <strong>system_<em>device</em>.c</strong> is provided by ARM but adapted by + the silicon vendor to match their actual device. As a <strong>minimum requirement</strong> + this file must provide a device specific system configuration function and a global variable + that contains the system frequency. It configures the device and initializes typically the + oscillator (PLL) that is part of the microcontroller device. +</p> +<p> + The file <strong>system_</strong><em><strong>device</strong></em><strong>.c</strong> must provide + as a minimum requirement the SystemInit function as shown below. +</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt">Function Definition</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void SystemInit (void)</td> + <td class="kt">Setup the microcontroller system. Typically this function configures the + oscillator (PLL) that is part of the microcontroller device. For systems + with variable clock speed it also updates the variable SystemCoreClock.<br> + SystemInit is called from startup<i>_device</i> file.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void SystemCoreClockUpdate (void)</td> + <td class="kt">Updates the variable SystemCoreClock and must be called whenever the + core clock is changed during program execution. SystemCoreClockUpdate() + evaluates the clock register settings and calculates the current core clock. +</td> + </tr> + </tbody> +</table> + +<p> + Also part of the file <strong>system_</strong><em><strong>device</strong></em><strong>.c</strong> + is the variable <strong>SystemCoreClock</strong> which contains the current CPU clock speed shown below. +</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt">Variable Definition</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t SystemCoreClock</td> + <td class="kt">Contains the system core clock (which is the system clock frequency supplied + to the SysTick timer and the processor core clock). This variable can be + used by the user application to setup the SysTick timer or configure other + parameters. It may also be used by debugger to query the frequency of the + debug timer or configure the trace clock speed.<br> + SystemCoreClock is initialized with a correct predefined value.<br><br> + The compiler must be configured to avoid the removal of this variable in + case that the application program is not using it. It is important for + debug systems that the variable is physically present in memory so that + it can be examined to configure the debugger.</td> + </tr> + </tbody> +</table> + +<p class="Note">Note</p> +<ul> + <li><p>The above definitions are the minimum requirements for the file <strong> + system_</strong><em><strong>device</strong></em><strong>.c</strong>. This + file may export more functions or variables that provide a more flexible + configuration of the microcontroller system.</p> + </li> +</ul> + + +<h2>Core Peripheral Access Layer</h2> + +<h3>Cortex-M Core Register Access</h3> +<p> + The following functions are defined in <strong>core_cm0.h</strong> / <strong>core_cm3.h</strong> + and provide access to Cortex-M core registers. +</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt">Function Definition</th> + <th class="kt">Core</th> + <th class="kt">Core Register</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __enable_irq (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">PRIMASK = 0</td> + <td class="kt">Global Interrupt enable (using the instruction <strong>CPSIE + i</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __disable_irq (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">PRIMASK = 1</td> + <td class="kt">Global Interrupt disable (using the instruction <strong> + CPSID i</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __set_PRIMASK (uint32_t value)</td> + <td class="kt">M0, M3</td> + <td class="kt">PRIMASK = value</td> + <td class="kt">Assign value to Priority Mask Register (using the instruction + <strong>MSR</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __get_PRIMASK (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">return PRIMASK</td> + <td class="kt">Return Priority Mask Register (using the instruction + <strong>MRS</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __enable_fault_irq (void)</td> + <td class="kt">M3</td> + <td class="kt">FAULTMASK = 0</td> + <td class="kt">Global Fault exception and Interrupt enable (using the + instruction <strong>CPSIE + f</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __disable_fault_irq (void)</td> + <td class="kt">M3</td> + <td class="kt">FAULTMASK = 1</td> + <td class="kt">Global Fault exception and Interrupt disable (using the + instruction <strong>CPSID f</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __set_FAULTMASK (uint32_t value)</td> + <td class="kt">M3</td> + <td class="kt">FAULTMASK = value</td> + <td class="kt">Assign value to Fault Mask Register (using the instruction + <strong>MSR</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __get_FAULTMASK (void)</td> + <td class="kt">M3</td> + <td class="kt">return FAULTMASK</td> + <td class="kt">Return Fault Mask Register (using the instruction <strong>MRS</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __set_BASEPRI (uint32_t value)</td> + <td class="kt">M3</td> + <td class="kt">BASEPRI = value</td> + <td class="kt">Set Base Priority (using the instruction <strong>MSR</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uiuint32_t __get_BASEPRI (void)</td> + <td class="kt">M3</td> + <td class="kt">return BASEPRI</td> + <td class="kt">Return Base Priority (using the instruction <strong>MRS</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __set_CONTROL (uint32_t value)</td> + <td class="kt">M0, M3</td> + <td class="kt">CONTROL = value</td> + <td class="kt">Set CONTROL register value (using the instruction <strong>MSR</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __get_CONTROL (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">return CONTROL</td> + <td class="kt">Return Control Register Value (using the instruction + <strong>MRS</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __set_PSP (uint32_t TopOfProcStack)</td> + <td class="kt">M0, M3</td> + <td class="kt">PSP = TopOfProcStack</td> + <td class="kt">Set Process Stack Pointer value (using the instruction + <strong>MSR</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __get_PSP (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">return PSP</td> + <td class="kt">Return Process Stack Pointer (using the instruction <strong>MRS</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __set_MSP (uint32_t TopOfMainStack)</td> + <td class="kt">M0, M3</td> + <td class="kt">MSP = TopOfMainStack</td> + <td class="kt">Set Main Stack Pointer (using the instruction <strong>MSR</strong>)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __get_MSP (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">return MSP</td> + <td class="kt">Return Main Stack Pointer (using the instruction <strong>MRS</strong>)</td> + </tr> + </tbody> +</table> + +<h3>Cortex-M Instruction Access</h3> +<p> + The following functions are defined in <strong>core_cm0.h</strong> / <strong>core_cm3.h</strong>and + generate specific Cortex-M instructions. The functions are implemented in the file + <strong>core_cm0.c</strong> / <strong>core_cm3.c</strong>. +</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt">Name</th> + <th class="kt">Core</th> + <th class="kt">Generated CPU Instruction</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __NOP (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">NOP</td> + <td class="kt">No Operation</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __WFI (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">WFI</td> + <td class="kt">Wait for Interrupt</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __WFE (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">WFE</td> + <td class="kt">Wait for Event</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __SEV (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">SEV</td> + <td class="kt">Set Event</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __ISB (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">ISB</td> + <td class="kt">Instruction Synchronization Barrier</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __DSB (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">DSB</td> + <td class="kt">Data Synchronization Barrier</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __DMB (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">DMB</td> + <td class="kt">Data Memory Barrier</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __REV (uint32_t value)</td> + <td class="kt">M0, M3</td> + <td class="kt">REV</td> + <td class="kt">Reverse byte order in integer value.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __REV16 (uint16_t value)</td> + <td class="kt">M0, M3</td> + <td class="kt">REV16</td> + <td class="kt">Reverse byte order in unsigned short value. </td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">sint32_t __REVSH (sint16_t value)</td> + <td class="kt">M0, M3</td> + <td class="kt">REVSH</td> + <td class="kt">Reverse byte order in signed short value with sign extension to integer.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __RBIT (uint32_t value)</td> + <td class="kt">M3</td> + <td class="kt">RBIT</td> + <td class="kt">Reverse bit order of value</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint8_t __LDREXB (uint8_t *addr)</td> + <td class="kt">M3</td> + <td class="kt">LDREXB</td> + <td class="kt">Load exclusive byte</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint16_t __LDREXH (uint16_t *addr)</td> + <td class="kt">M3</td> + <td class="kt">LDREXH</td> + <td class="kt">Load exclusive half-word</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __LDREXW (uint32_t *addr)</td> + <td class="kt">M3</td> + <td class="kt">LDREXW</td> + <td class="kt">Load exclusive word</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __STREXB (uint8_t value, uint8_t *addr)</td> + <td class="kt">M3</td> + <td class="kt">STREXB</td> + <td class="kt">Store exclusive byte</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __STREXB (uint16_t value, uint16_t *addr)</td> + <td class="kt">M3</td> + <td class="kt">STREXH</td> + <td class="kt">Store exclusive half-word</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t __STREXB (uint32_t value, uint32_t *addr)</td> + <td class="kt">M3</td> + <td class="kt">STREXW</td> + <td class="kt">Store exclusive word</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void __CLREX (void)</td> + <td class="kt">M3</td> + <td class="kt">CLREX</td> + <td class="kt">Remove the exclusive lock created by __LDREXB, __LDREXH, or __LDREXW</td> + </tr> + </tbody> +</table> + + +<h3>NVIC Access Functions</h3> +<p> + The CMSIS provides access to the NVIC via the register interface structure and several helper + functions that simplify the setup of the NVIC. The CMSIS HAL uses IRQ numbers (IRQn) to + identify the interrupts. The first device interrupt has the IRQn value 0. Therefore negative + IRQn values are used for processor core exceptions. +</p> +<p> + For the IRQn values of core exceptions the file <strong><em>device.h</em></strong> provides + the following enum names. +</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt" nowrap="nowrap">Core Exception enum Value</th> + <th class="kt">Core</th> + <th class="kt">IRQn</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">NonMaskableInt_IRQn</td> + <td class="kt">M0, M3</td> + <td class="kt">-14</td> + <td class="kt">Cortex-M Non Maskable Interrupt</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">HardFault_IRQn</td> + <td class="kt">M0, M3</td> + <td class="kt">-13</td> + <td class="kt">Cortex-M Hard Fault Interrupt</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">MemoryManagement_IRQn</td> + <td class="kt">M3</td> + <td class="kt">-12</td> + <td class="kt">Cortex-M Memory Management Interrupt</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">BusFault_IRQn</td> + <td class="kt">M3</td> + <td class="kt">-11</td> + <td class="kt">Cortex-M Bus Fault Interrupt</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">UsageFault_IRQn</td> + <td class="kt">M3</td> + <td class="kt">-10</td> + <td class="kt">Cortex-M Usage Fault Interrupt</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">SVCall_IRQn</td> + <td class="kt">M0, M3</td> + <td class="kt">-5</td> + <td class="kt">Cortex-M SV Call Interrupt </td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">DebugMonitor_IRQn</td> + <td class="kt">M3</td> + <td class="kt">-4</td> + <td class="kt">Cortex-M Debug Monitor Interrupt</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">PendSV_IRQn</td> + <td class="kt">M0, M3</td> + <td class="kt">-2</td> + <td class="kt">Cortex-M Pend SV Interrupt</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">SysTick_IRQn</td> + <td class="kt">M0, M3</td> + <td class="kt">-1</td> + <td class="kt">Cortex-M System Tick Interrupt</td> + </tr> + </tbody> +</table> + +<p>The following functions simplify the setup of the NVIC. +The functions are defined as <strong>static inline</strong>.</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt" nowrap="nowrap">Name</th> + <th class="kt">Core</th> + <th class="kt">Parameter</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void NVIC_SetPriorityGrouping (uint32_t PriorityGroup)</td> + <td class="kt">M3</td> + <td class="kt">Priority Grouping Value</td> + <td class="kt">Set the Priority Grouping (Groups . Subgroups)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t NVIC_GetPriorityGrouping (void)</td> + <td class="kt">M3</td> + <td class="kt">(void)</td> + <td class="kt">Get the Priority Grouping (Groups . Subgroups)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void NVIC_EnableIRQ (IRQn_Type IRQn)</td> + <td class="kt">M0, M3</td> + <td class="kt">IRQ Number</td> + <td class="kt">Enable IRQn</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void NVIC_DisableIRQ (IRQn_Type IRQn)</td> + <td class="kt">M0, M3</td> + <td class="kt">IRQ Number</td> + <td class="kt">Disable IRQn</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t NVIC_GetPendingIRQ (IRQn_Type IRQn)</td> + <td class="kt">M0, M3</td> + <td class="kt">IRQ Number</td> + <td class="kt">Return 1 if IRQn is pending else 0</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void NVIC_SetPendingIRQ (IRQn_Type IRQn)</td> + <td class="kt">M0, M3</td> + <td class="kt">IRQ Number</td> + <td class="kt">Set IRQn Pending</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void NVIC_ClearPendingIRQ (IRQn_Type IRQn)</td> + <td class="kt">M0, M3</td> + <td class="kt">IRQ Number</td> + <td class="kt">Clear IRQn Pending Status</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t NVIC_GetActive (IRQn_Type IRQn)</td> + <td class="kt">M3</td> + <td class="kt">IRQ Number</td> + <td class="kt">Return 1 if IRQn is active else 0</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void NVIC_SetPriority (IRQn_Type IRQn, uint32_t priority)</td> + <td class="kt">M0, M3</td> + <td class="kt">IRQ Number, Priority</td> + <td class="kt">Set Priority for IRQn<br> + (not threadsafe for Cortex-M0)</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t NVIC_GetPriority (IRQn_Type IRQn)</td> + <td class="kt">M0, M3</td> + <td class="kt">IRQ Number</td> + <td class="kt">Get Priority for IRQn</td> + </tr> + <tr> +<!-- <td class="kt" nowrap="nowrap">uint32_t NVIC_EncodePriority (uint32_t PriorityGroup, uint32_t PreemptPriority, uint32_t SubPriority)</td> --> + <td class="kt">uint32_t NVIC_EncodePriority (uint32_t PriorityGroup, uint32_t PreemptPriority, uint32_t SubPriority)</td> + <td class="kt">M3</td> + <td class="kt">IRQ Number, Priority Group, Preemptive Priority, Sub Priority</td> + <td class="kt">Encode priority for given group, preemptive and sub priority</td> + </tr> +<!-- <td class="kt" nowrap="nowrap">NVIC_DecodePriority (uint32_t Priority, uint32_t PriorityGroup, uint32_t* pPreemptPriority, uint32_t* pSubPriority)</td> --> + <td class="kt">NVIC_DecodePriority (uint32_t Priority, uint32_t PriorityGroup, uint32_t* pPreemptPriority, uint32_t* pSubPriority)</td> + <td class="kt">M3</td> + <td class="kt">IRQ Number, Priority, pointer to Priority Group, pointer to Preemptive Priority, pointer to Sub Priority</td> + <td class="kt">Deccode given priority to group, preemptive and sub priority</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void NVIC_SystemReset (void)</td> + <td class="kt">M0, M3</td> + <td class="kt">(void)</td> + <td class="kt">Resets the System</td> + </tr> + </tbody> +</table> +<p class="Note">Note</p> +<ul> + <li><p>The processor exceptions have negative enum values. Device specific interrupts + have positive enum values and start with 0. The values are defined in + <b><em>device.h</em></b> file. + </p> + </li> + <li><p>The values for <b>PreemptPriority</b> and <b>SubPriority</b> + used in functions <b>NVIC_EncodePriority</b> and <b>NVIC_DecodePriority</b> + depend on the available __NVIC_PRIO_BITS implemented in the NVIC. + </p> + </li> +</ul> + + +<h3>SysTick Configuration Function</h3> + +<p>The following function is used to configure the SysTick timer and start the +SysTick interrupt.</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt" nowrap="nowrap">Name</th> + <th class="kt">Parameter</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">uint32_t Sys<span class="style1">TickConfig + (uint32_t ticks)</span></td> + <td class="kt">ticks is SysTick counter reload value</td> + <td class="kt">Setup the SysTick timer and enable the SysTick interrupt. After this + call the SysTick timer creates interrupts with the specified time + interval. <br> + <br> + Return: 0 when successful, 1 on failure.<br> + </td> + </tr> + </tbody> +</table> + + +<h3>Cortex-M3 ITM Debug Access</h3> + +<p>The Cortex-M3 incorporates the Instrumented Trace Macrocell (ITM) that +provides together with the Serial Viewer Output trace capabilities for the +microcontroller system. The ITM has 32 communication channels; two ITM +communication channels are used by CMSIS to output the following information:</p> +<ul> + <li>ITM Channel 0: implements the <strong>ITM_SendChar</strong> function + which can be used for printf-style output via the debug interface.</li> + <li>ITM Channel 31: is reserved for the RTOS kernel and can be used for + kernel awareness debugging.</li> +</ul> +<p class="Note">Note</p> +<ul> + <li><p>The ITM channel 31 is selected for the RTOS kernel since some kernels + may use the Privileged level for program execution. ITM + channels have 4 groups with 8 channels each, whereby each group can be + configured for access rights in the Unprivileged level. The ITM channel 0 + may be therefore enabled for the user task whereas ITM channel 31 may be + accessible only in Privileged level from the RTOS kernel itself.</p> + </li> +</ul> + +<p>The prototype of the <strong>ITM_SendChar</strong> routine is shown in the +table below.</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt" nowrap="nowrap">Name</th> + <th class="kt">Parameter</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">void uint32_t ITM_SendChar(uint32_t chr)</td> + <td class="kt">character to output</td> + <td class="kt">The function outputs a character via the ITM channel 0. The + function returns when no debugger is connected that has booked the + output. It is blocking when a debugger is connected, but the + previous character send is not transmitted. <br><br> + Return: the input character 'chr'.</td> + </tr> + </tbody> +</table> + +<p> + Example for the usage of the ITM Channel 31 for RTOS Kernels: +</p> +<pre> + // check if debugger connected and ITM channel enabled for tracing + if ((CoreDebug->DEMCR & CoreDebug_DEMCR_TRCENA) && + (ITM->TCR & ITM_TCR_ITMENA) && + (ITM->TER & (1UL << 31))) { + // transmit trace data + while (ITM->PORT31_U32 == 0); + ITM->PORT[31].u8 = task_id; // id of next task + while (ITM->PORT[31].u32 == 0); + ITM->PORT[31].u32 = task_status; // status information + }</pre> + + +<h3>Cortex-M3 additional Debug Access</h3> + +<p>CMSIS provides additional debug functions to enlarge the Cortex-M3 Debug Access. +Data can be transmitted via a certain global buffer variable towards the target system.</p> + +<p>The buffer variable and the prototypes of the additional functions are shown in the +table below.</p> + +<table class="kt" border="0" cellpadding="0" cellspacing="0"> + <tbody> + <tr> + <th class="kt" nowrap="nowrap">Name</th> + <th class="kt">Parameter</th> + <th class="kt">Description</th> + </tr> + <tr> + <td class="kt" nowrap="nowrap">extern volatile int ITM_RxBuffer</td> + <td class="kt"> </td> + <td class="kt">Buffer to transmit data towards debug system. <br><br> + Value 0x5AA55AA5 indicates that buffer is empty.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">int ITM_ReceiveChar (void)</td> + <td class="kt">none</td> + <td class="kt">The nonblocking functions returns the character stored in + ITM_RxBuffer. <br><br> + Return: -1 indicates that no character was received.</td> + </tr> + <tr> + <td class="kt" nowrap="nowrap">int ITM_CheckChar (void)</td> + <td class="kt">none</td> + <td class="kt">The function checks if a character is available in ITM_RxBuffer. <br><br> + Return: 1 indicates that a character is available, 0 indicates that + no character is available.</td> + </tr> + </tbody> +</table> + + +<h2><a name="5"></a>CMSIS Example</h2> +<p> + The following section shows a typical example for using the CMSIS layer in user applications. + The example is based on a STM32F10x Device. +</p> +<pre> +#include "stm32f10x.h" + +volatile uint32_t msTicks; /* timeTicks counter */ + +void SysTick_Handler(void) { + msTicks++; /* increment timeTicks counter */ +} + +__INLINE static void Delay (uint32_t dlyTicks) { + uint32_t curTicks = msTicks; + + while ((msTicks - curTicks) < dlyTicks); +} + +__INLINE static void LED_Config(void) { + ; /* Configure the LEDs */ +} + +__INLINE static void LED_On (uint32_t led) { + ; /* Turn On LED */ +} + +__INLINE static void LED_Off (uint32_t led) { + ; /* Turn Off LED */ +} + +int main (void) { + if (SysTick_Config (SystemCoreClock / 1000)) { /* Setup SysTick for 1 msec interrupts */ + ; /* Handle Error */ + while (1); + } + + LED_Config(); /* configure the LEDs */ + + while(1) { + LED_On (0x100); /* Turn on the LED */ + Delay (100); /* delay 100 Msec */ + LED_Off (0x100); /* Turn off the LED */ + Delay (100); /* delay 100 Msec */ + } +}</pre> + + +</body></html> \ No newline at end of file