ARM STM32 Study Note_1/GPIO

Experiment 1. LED

* GPIO in STM32 has 8 modes, it is an enum variable defined in the stm32f10x_gpio.h

    typedef enum

    { GPIO_Mode_AIN = 0x0,

      GPIO_Mode_IN_FLOATING = 0x04,

      GPIO_Mode_IPD = 0x28,

      GPIO_Mode_IPU = 0x48,

      GPIO_Mode_Out_OD = 0x14,

      GPIO_Mode_Out_PP = 0x10,

      GPIO_Mode_AF_OD = 0x1C,

      GPIO_Mode_AF_PP = 0x18

    }GPIOMode_TypeDef;

* Before use GPIO, have to define the mode and speed

 

   GPIO_Speed_10MHz Output Maximum Frequency = 10 MHz

   GPIO_Speed_2MHz Output Maximum Frequency = 2 MHz

   GPIO_Speed_50MHz Output Maximum Frequency = 50 MHz

  

   typedef enum

  {

    GPIO_Speed_10MHz = 1,

    GPIO_Speed_2MHz,

    GPIO_Speed_50MHz

  }GPIOSpeed_TypeDef;

 

* Both Pin,speed and mode is in one structure defined in the stm32f10x_gpio.h

  typedef struct

 {

  u16 GPIO_Pin;

  GPIOSpeed_TypeDef GPIO_Speed;

  GPIOMode_TypeDef GPIO_Mode;

  } GPIO_InitTypeDef;

-Note:

 *RCC: Reset AND Clock Controler

 *There are three internal busses:

    -Advanced High Performance Bus (AHB)

    -Low speed Advanced Peripherial Bus (APB1)

    -High speed Advanced Peripherial Bus (APB2)

* RCC_APB2Periph_GPIOD => IO port D clock

 

* GPIO_Init function

 

* GPIO register structure

* GPIO_ResetBits/GPIO_SetBits

* Basic Variables 

  typedef unsigned long  u32;

  typedef unsigned short u16;

  typedef unsigned char  u8;

 

  #define     __IO    volatile                  /*!< defines 'read / write' permissions   */

 

  typedef unsigned           int uint32_t;     //in the stdint.h

 

* File Structure

Questions:

1. what is RCC_APB2Periph_AFIO, and how to use it?