/** \page using_pg Using CMSIS in Embedded Applications \details To use the CMSIS-Core (Cortex-M) the following files are added to the embedded application: - \ref startup_c_pg (formerly \ref startup_s_pg) with reset handler and exception vectors. - \ref system_c_pg with general device configuration (i.e. for clock and BUS setup). - \ref device_h_pg gives access to processor core and all peripherals. \note The files \ref startup_c_pg (or \ref startup_s_pg) and \ref system_c_pg may require application specific adaptations and therefore should be copied into the application project folder prior configuration. The \ref device_h_pg is included in all source files that need device access and can be stored on a central include folder that is generic for all projects. The \ref startup_c_pg (or \ref startup_s_pg) is executed after reset and calls \ref SystemInit. After the system initialization control is transferred to the C/C++ run-time library which performs initialization and calls the \b main function in the user code. In addition the \ref startup_c_pg (or \ref startup_s_pg) contains all exception and interrupt vectors and implements a default function for every interrupt. It may also contain stack and heap configurations for the user application. The \ref system_c_pg performs the setup for the processor clock. The variable \ref SystemCoreClock indicates the CPU clock speed. \ref system_init_gr describes the minimum feature set. In addition the file may contain functions for the memory BUS setup and clock re-configuration. The \ref device_h_pg is the central include file that the application programmer is using in the C source code. It provides the following features: - \ref peripheral_gr provides a standardized register layout for all peripherals. Optionally functions for device-specific peripherals may be available. - \ref NVIC_gr can be accessed with standardized symbols and functions for the Nested Interrupt Vector Controller (NVIC) are provided. - \ref intrinsic_CPU_gr allow to access special instructions, for example for activating sleep mode or the NOP instruction. - \ref intrinsic_SIMD_gr provide access to the DSP-oriented instructions. - \ref SysTick_gr function to configure and start a periodic timer interrupt. - \ref ITM_Debug_gr are functions that allow printf-style I/O via the CoreSight Debug Unit and ITM communication. CMSIS-Pack provides the <b>\#define CMSIS_header_file</b> in <a href="../../Pack/html/pdsc_components_pg.html#RTE_Components_h"><b>RTE_Components.h</b></a> which gives you access to this <b><i>device</i>.h</b> file. \image html "CMSIS_CORE_Files_USER.png" "CMSIS-Core (Cortex-M) User Files" The CMSIS-Core (Cortex-M) system files are device specific. In addition, the deprecated \ref startup_s_pg is also compiler vendor specific. The versions provided by CMSIS are only generic templates. The adopted versions for a concrete device are typically provided by the device vendor through the according device family pack (DFP). For example, the following files are provided by the STM32F10x device family pack: <table class="cmtable"> <tr> <th>File</th> <th>Description</th> </tr> <tr> <td>".\Device\Source\ARM\startup_stm32f10x_cl.s"</td> <td>\ref startup_s_pg for the STM32F10x Connectivity Line device variants.</td> </tr> <tr> <td>".\Device\Source\system_stmf10x.c"</td> <td>\ref system_c_pg for the STM32F10x device families.</td> </tr> <tr> <td>".\Device\Include\stm32f10x.h"</td> <td>\ref device_h_pg for the STM32F10x device families.</td> </tr> <tr> <td>".\Device\Include\system_stm32f10x.h"</td> <td>\ref system_Device_h_sec for the STM32F10x device families.</td> </tr> </table> \note The silicon vendors create these device-specific CMSIS-Core (Cortex-M) files based on \ref templates_pg provide by Arm. Thereafter, the functions described under <a href="modules.html">\b Reference </a> can be used in the application. \b Examples - \subpage using_CMSIS is a simple example that shows the usage of the CMSIS layer. - \subpage using_VTOR_pg shows how to remap the interrupt vector table. - \subpage using_ARM_pg explains how to use CMSIS-Core (Cortex-M) for Arm processors. \page using_CMSIS Basic CMSIS Example A typical example for using the CMSIS layer is provided below. The example is based on a STM32F10x Device. \code #include <stm32f10x.h> // File name depends on device used uint32_t volatile msTicks; // Counter for millisecond Interval void SysTick_Handler (void) { // SysTick Interrupt Handler msTicks++; // Increment Counter } void WaitForTick (void) { uint32_t curTicks; curTicks = msTicks; // Save Current SysTick Value while (msTicks == curTicks) { // Wait for next SysTick Interrupt __WFE (); // Power-Down until next Event/Interrupt } } void TIM1_UP_IRQHandler (void) { // Timer Interrupt Handler ; // Add user code here } void timer1_init(int frequency) { // Set up Timer (device specific) NVIC_SetPriority (TIM1_UP_IRQn, 1); // Set Timer priority NVIC_EnableIRQ (TIM1_UP_IRQn); // Enable Timer Interrupt } void Device_Initialization (void) { // Configure & Initialize MCU if (SysTick_Config (SystemCoreClock / 1000)) { // SysTick 1mSec : // Handle Error } timer1_init (); // setup device-specific timer } // The processor clock is initialized by CMSIS startup + system file void main (void) { // user application starts here Device_Initialization (); // Configure & Initialize MCU while (1) { // Endless Loop (the Super-Loop) __disable_irq (); // Disable all interrupts Get_InputValues (); // Read Values __enable_irq (); // Enable all interrupts Calculation_Response (); // Calculate Results Output_Response (); // Output Results WaitForTick (); // Synchronize to SysTick Timer } } \endcode CMSIS-Pack provides the <b>\#define CMSIS_header_file</b> in <a href="../../Pack/html/pdsc_components_pg.html#RTE_Components_h"><b>RTE_Components.h</b></a> which gives you access to the <b><i>device</i>.h</b> file of a project. This allows you to generate generic software components that use the device selected in a project. \code #include "RTE_Components.h" // include information about project configuration #include CMSIS_device_header // include <device>.h file \endcode \page using_VTOR_pg Using Interrupt Vector Remap Most Cortex-M processors provide VTOR register for remapping interrupt vectors. The following example shows a typical use case where the interrupt vectors are copied to RAM and the SysTick_Handler is replaced. \code #include "ARMCM3.h" // Device header #define VECTORTABLE_SIZE (240) /* size of the used vector tables */ /* see startup file startup_ARMCM3.c */ #define VECTORTABLE_ALIGNMENT (0x100U) /* 16 Cortex + 32 ARMCM3 = 48 words */ /* next power of 2 = 256 */ /* externals from startup_ARMCM3.c */ extern uint32_t __VECTOR_TABLE[VECTORTABLE_SIZE]; /* vector table ROM */ /* new vector table in RAM, same size as vector table in ROM */ uint32_t vectorTable_RAM[VECTORTABLE_SIZE] __attribute__(( aligned (VECTORTABLE_ALIGNMENT) )); /*---------------------------------------------------------------------------- SysTick_Handler *----------------------------------------------------------------------------*/ volatile uint32_t msTicks = 0; /* counts 1ms timeTicks */ void SysTick_Handler(void) { msTicks++; /* increment counter */ } /*---------------------------------------------------------------------------- SysTick_Handler (RAM) *----------------------------------------------------------------------------*/ volatile uint32_t msTicks_RAM = 0; /* counts 1ms timeTicks */ void SysTick_Handler_RAM(void) { msTicks_RAM++; /* increment counter */ } /*---------------------------------------------------------------------------- MAIN function *----------------------------------------------------------------------------*/ int main (void) { uint32_t i; for (i = 0; i < VECTORTABLE_SIZE; i++) { vectorTable_RAM[i] = __VECTOR_TABLE[i]; /* copy vector table to RAM */ } /* replace SysTick Handler */ vectorTable_RAM[SysTick_IRQn + 16] = (uint32_t)SysTick_Handler_RAM; /* relocate vector table */ __disable_irq(); SCB->VTOR = (uint32_t)&vectorTable_RAM; __DSB(); __enable_irq(); SystemCoreClockUpdate(); /* Get Core Clock Frequency */ SysTick_Config(SystemCoreClock / 1000ul); /* Setup SysTick Timer for 1 msec */ w...
robert72001