NVIC_Priority

  ******************** (C) COPYRIGHT 2010 STMicroelectronics *******************
  * @file    NVIC/Priority/readme.txt 
  * @author  MCD Application Team
  * @version V3.4.0
  * @date    10/15/2010
  * @brief   Description of the NVIC Priority Example.
  ******************************************************************************
  * THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
  * WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
  * TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
  * DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
  * FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
  * CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
  ******************************************************************************
   
Example Description

This example demonstrates the use of the Nested Vectored Interrupt Controller (NVIC):

In the key button EXTI Line interrupt routine the Wakeup button EXTI Line and SysTick preemption priorities are inverted. In the Wakeup button EXTI Line interrupt routine the pending bit of the SysTick interrupt is set this will cause SysTick ISR to preempt the Wakeup button EXTI Line ISR only if it has higher preemption priority.

The system behaves as following:

1) The first time Key button EXTI Line interrupt occurs the SysTick preemption become higher than Wakeup button EXTI Line one. So when the Wakeup button EXTI Line interrupt occurs, the SysTick ISR is executed and the PreemptionOccured variable become TRUE and the four leds (LED1, LED2, LED3, LED4) start toggling.

2) When the next Key button EXTI Line interrupt occurs the SysTick preemption become lower than Wakeup button EXTI Line one. So when the Wakeup button EXTI Line interrupt occurs, the PreemptionOccured variable became FALSE and the four leds (LED1, LED2, LED3, LED4) stop toggling.

Then this behavior is repeated from point 1) in an infinite loop.

Directory contents
Hardware and Software environment
How to use it ?

In order to make the program work, you must do the following :

Tip: You can tailor the provided project template to run this example, for more details please refer to "stm32f10x_stdperiph_lib_um.chm" user manual; select "Peripheral Examples" then follow the instructions provided in "How to proceed" section.

Note:
  • Low-density Value line devices are STM32F100xx microcontrollers where the Flash memory density ranges between 16 and 32 Kbytes.
  • Low-density devices are STM32F101xx, STM32F102xx and STM32F103xx microcontrollers where the Flash memory density ranges between 16 and 32 Kbytes.
  • Medium-density Value line devices are STM32F100xx microcontrollers where the Flash memory density ranges between 64 and 128 Kbytes.
  • Medium-density devices are STM32F101xx, STM32F102xx and STM32F103xx microcontrollers where the Flash memory density ranges between 64 and 128 Kbytes.
  • High-density Value line devices are STM32F100xx microcontrollers where the Flash memory density ranges between 256 and 512 Kbytes.
  • High-density devices are STM32F101xx and STM32F103xx microcontrollers where the Flash memory density ranges between 256 and 512 Kbytes.
  • XL-density devices are STM32F101xx and STM32F103xx microcontrollers where the Flash memory density ranges between 512 and 1024 Kbytes.
  • Connectivity line devices are STM32F105xx and STM32F107xx microcontrollers.

© COPYRIGHT 2010 STMicroelectronics

STM32F10x Standard Peripherals Library: Footer

 

 

 

      For complete documentation on STM32(CORTEX M3) 32-bit Microcontrollers platform visit  www.st.com/STM32