Arduino_Core_STM32---pinMode()实现分析

pinMode()定义

Arduino平台的易于使用性主要就体现在屏蔽的大量底层细节的实现，对于该函数来说也不例外。虽然该函数只有两个参数（arduino引脚号和模式），但这两个参数需要多层的映射才能转化为具体适合STM32芯片的配置信息，并调用底层接口完成配置。

从下面源码中可以看出主要由两个函数来完成引脚模式配置的：digitalPinToPinName()和pinfunction()。在具体深入下面两个函数之前我们需要一些预备知识—该库对于STM32硬件端口和引脚的封装。

void pinMode(uint32_t ulPin, uint32_t ulMode)

{

  PinName p = digitalPinToPinName(ulPin);

  if (p != NC) {

    // If the pin that support PWM or DAC output, we need to turn it off

/* 省略关闭PWM或DAC输出的代码 */

    switch (ulMode) {

      case INPUT: /* INPUT_FLOATING */

        pin_function(p, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));

        break;

      case INPUT_PULLUP:

        pin_function(p, STM_PIN_DATA(STM_MODE_INPUT, GPIO_PULLUP, 0));

        break;

      case INPUT_PULLDOWN:

        pin_function(p, STM_PIN_DATA(STM_MODE_INPUT, GPIO_PULLDOWN, 0));

        break;

      case INPUT_ANALOG:

        pin_function(p, STM_PIN_DATA(STM_MODE_ANALOG, GPIO_NOPULL, 0));

        break;

      case OUTPUT:

        pin_function(p, STM_PIN_DATA(STM_MODE_OUTPUT_PP, GPIO_NOPULL, 0));

        break;

      case OUTPUT_OPEN_DRAIN:

        pin_function(p, STM_PIN_DATA(STM_MODE_OUTPUT_OD, GPIO_NOPULL, 0));

        break;

      default:

        Error_Handler();

        break;

    }

  }

}

预备知识

PortNames.c/h文件解析

定义端口枚举：

typedef enum {

  FirstPort = 0x00,

  PortA = FirstPort,

  PortB,

#if defined GPIOC_BASE

  PortC,

#endif

#if defined GPIOD_BASE

  PortD,

#endif

/* 省略部分定义 */

  PortZ,

  LastPort = PortZ - 1

} PortName;

#define MAX_NB_PORT (LastPort-FirstPort+1)

定义GPIO端口表

GPIO_TypeDef *GPIOPort[MAX_NB_PORT] = {

  (GPIO_TypeDef *)GPIOA_BASE,

  (GPIO_TypeDef *)GPIOB_BASE

#if defined GPIOC_BASE

  , (GPIO_TypeDef *)GPIOC_BASE

#endif

#if defined GPIOD_BASE

  , (GPIO_TypeDef *)GPIOD_BASE

#endif

/* 省略部分代码 */

};

操作函数：返回GPIO基地址

/* Return GPIO base address */

#define get_GPIO_Port(p) ((p < MAX_NB_PORT) ? GPIOPort[p] : (GPIO_TypeDef *)NULL)

pinNames.h文件解析

引脚定义：实际引脚定义中也包含的端口信息，高四位存储端口信息（PortName的枚举值），低四位存储引脚号（0-15）。

typedef enum {

  // Not connected

  NC = (int)0xFFFFFFFF,

  // Pin name definition

  PA_0  = (PortA << 4) + 0x00,

  PA_1  = (PortA << 4) + 0x01,

  PA_2  = (PortA << 4) + 0x02,

  PA_3  = (PortA << 4) + 0x03,

  PA_4  = (PortA << 4) + 0x04,

  PA_5  = (PortA << 4) + 0x05,

  PA_6  = (PortA << 4) + 0x06,

  PA_7  = (PortA << 4) + 0x07,

  PA_8  = (PortA << 4) + 0x08,

  PA_9  = (PortA << 4) + 0x09,

  PA_10 = (PortA << 4) + 0x0A,

  PA_11 = (PortA << 4) + 0x0B,

  PA_12 = (PortA << 4) + 0x0C,

  PA_13 = (PortA << 4) + 0x0D,

  PA_14 = (PortA << 4) + 0x0E,

  PA_15 = (PortA << 4) + 0x0F,

  PB_0  = (PortB << 4) + 0x00,

  PB_1  = (PortB << 4) + 0x01,

  PB_2  = (PortB << 4) + 0x02,

  PB_3  = (PortB << 4) + 0x03,

  PB_4  = (PortB << 4) + 0x04,

  PB_5  = (PortB << 4) + 0x05,

  PB_6  = (PortB << 4) + 0x06,

  PB_7  = (PortB << 4) + 0x07,

  PB_8  = (PortB << 4) + 0x08,

  PB_9  = (PortB << 4) + 0x09,

  PB_10 = (PortB << 4) + 0x0A,

  PB_11 = (PortB << 4) + 0x0B,

  PB_12 = (PortB << 4) + 0x0C,

  PB_13 = (PortB << 4) + 0x0D,

  PB_14 = (PortB << 4) + 0x0E,

  PB_15 = (PortB << 4) + 0x0F,

#if defined GPIOC_BASE

  /* 省略GPIOC的引脚定义 */

#endif

  /* 省略GPIOD-GPIOJ之间的引脚定义 */

  // Specific pin name

  PADC_BASE = 0x100,

  /* 省略部分特殊引脚的定义 */

  // Specific pin name define in the variant

#if __has_include("PinNamesVar.h")

#include "PinNamesVar.h"

#endif

  P_END = NC

} PinName;

STM32达人的GPIO使用心得

使用在pin_function函数中的STM引脚数据，按如下32位格式的编码：

[2:0] Function (like in MODER reg) : Input / Output / Alt / Analog

[3] Output Push-Pull / Open Drain (as in OTYPER reg)

[5:4] as in PUPDR reg: No Pull, Pull-up, Pull-Down

[7:6] Reserved for speed config (as in OSPEEDR), but not used yet

[14:8] Alternate Num (as in AFRL/AFRG reg)

[19:15] Channel (Analog/Timer specific)

[20] Inverted (Analog/Timer specific)

[21] Analog ADC control - Only valid for specific families

[32:22] Reserved

编码信息的细节定义

#define STM_PIN_FUNCTION_MASK 0x07

#define STM_PIN_FUNCTION_SHIFT 0

#define STM_PIN_FUNCTION_BITS (STM_PIN_FUNCTION_MASK << STM_PIN_FUNCTION_SHIFT)

#define STM_PIN_OD_MASK 0x01

#define STM_PIN_OD_SHIFT 3

#define STM_PIN_OD_BITS (STM_PIN_OD_MASK << STM_PIN_OD_SHIFT)

#define STM_PIN_PUPD_MASK 0x03

#define STM_PIN_PUPD_SHIFT 4

#define STM_PIN_PUPD_BITS (STM_PIN_PUPD_MASK << STM_PIN_PUPD_SHIFT)

#define STM_PIN_SPEED_MASK 0x03

#define STM_PIN_SPEED_SHIFT 6

#define STM_PIN_SPEED_BITS (STM_PIN_SPEED_MASK << STM_PIN_SPEED_SHIFT)

#define STM_PIN_AFNUM_MASK 0x7F

#define STM_PIN_AFNUM_SHIFT 8

#define STM_PIN_AFNUM_BITS (STM_PIN_AFNUM_MASK << STM_PIN_AFNUM_SHIFT)

#define STM_PIN_CHAN_MASK 0x1F

#define STM_PIN_CHAN_SHIFT 15

#define STM_PIN_CHANNEL_BIT (STM_PIN_CHAN_MASK << STM_PIN_CHAN_SHIFT)

#define STM_PIN_INV_MASK 0x01

#define STM_PIN_INV_SHIFT 20

#define STM_PIN_INV_BIT (STM_PIN_INV_MASK << STM_PIN_INV_SHIFT)

#define STM_PIN_AN_CTRL_MASK 0x01

#define STM_PIN_AN_CTRL_SHIFT 21

#define STM_PIN_ANALOG_CONTROL_BIT (STM_PIN_AN_CTRL_MASK << STM_PIN_AN_CTRL_SHIFT)

方便从数据编码中解析出具体配置的宏函数：

#define STM_PIN_FUNCTION(X)         (((X) >> STM_PIN_FUNCTION_SHIFT) & STM_PIN_FUNCTION_MASK)

#define STM_PIN_OD(X)               (((X) >> STM_PIN_OD_SHIFT) & STM_PIN_OD_MASK)

#define STM_PIN_PUPD(X)             (((X) >> STM_PIN_PUPD_SHIFT) & STM_PIN_PUPD_MASK)

#define STM_PIN_SPEED(X)            (((X) >> STM_PIN_SPEED_SHIFT) & STM_PIN_SPEED_MASK)

#define STM_PIN_AFNUM(X)            (((X) >> STM_PIN_AFNUM_SHIFT) & STM_PIN_AFNUM_MASK)

#define STM_PIN_CHANNEL(X)          (((X) >> STM_PIN_CHAN_SHIFT) & STM_PIN_CHAN_MASK)

#define STM_PIN_INVERTED(X)         (((X) >> STM_PIN_INV_SHIFT) & STM_PIN_INV_MASK)

#define STM_PIN_ANALOG_CONTROL(X)   (((X) >> STM_PIN_AN_CTRL_SHIFT) & STM_PIN_AN_CTRL_MASK)

#define STM_PIN_MODE(X)             ((STM_PIN_OD((X)) << 4) |

                                      (STM_PIN_FUNCTION((X)) & (~STM_PIN_OD_BITS)))

#define STM_PIN_DEFINE(FUNC_OD, PUPD, AFNUM)  ((int)(FUNC_OD) |

                          ((PUPD  & STM_PIN_PUPD_MASK) << STM_PIN_PUPD_SHIFT) |

                          ((AFNUM & STM_PIN_AFNUM_MASK) << STM_PIN_AFNUM_SHIFT))

#define STM_PIN_DEFINE_EXT(FUNC_OD, PUPD, AFNUM, CHAN, INV)

                                            ((int)(FUNC_OD) |

                       ((PUPD   & STM_PIN_PUPD_MASK) << STM_PIN_PUPD_SHIFT) |

                       ((AFNUM  & STM_PIN_AFNUM_MASK) << STM_PIN_AFNUM_SHIFT) |

                       ((CHAN   & STM_PIN_CHAN_MASK) << STM_PIN_CHAN_SHIFT) |

                       ((INV    & STM_PIN_INV_MASK) << STM_PIN_INV_SHIFT))

为方便外部使用定义的宏：

/*

 * MACROS to support the legacy definition of PIN formats

 * The STM_MODE_ defines contain the function and the Push-pull/OpenDrain

 * configuration (legacy inheritance).

 */

#define STM_PIN_DATA(FUNC_OD, PUPD, AFNUM)

            STM_PIN_DEFINE(FUNC_OD, PUPD, AFNUM)

#define STM_PIN_DATA_EXT(FUNC_OD, PUPD, AFNUM, CHANNEL, INVERTED)

            STM_PIN_DEFINE_EXT(FUNC_OD, PUPD, AFNUM, CHANNEL, INVERTED)

typedef enum {

  STM_PIN_INPUT = 0,

  STM_PIN_OUTPUT = 1,

  STM_PIN_ALTERNATE = 2,

  STM_PIN_ANALOG = 3,

} StmPinFunction;

#define STM_MODE_INPUT               (STM_PIN_INPUT)

#define STM_MODE_OUTPUT_PP           (STM_PIN_OUTPUT)

#define STM_MODE_OUTPUT_OD           (STM_PIN_OUTPUT | STM_PIN_OD_BITS)

#define STM_MODE_AF_PP               (STM_PIN_ALTERNATE)

#define STM_MODE_AF_OD               (STM_PIN_ALTERNATE | STM_PIN_OD_BITS)

#define STM_MODE_ANALOG              (STM_PIN_ANALOG)

#define STM_MODE_ANALOG_ADC_CONTROL  (STM_PIN_ANALOG | STM_PIN_ANALOG_CONTROL_BIT)

digitalPinToPinName()函数

这里我们要搞清楚几个关于引脚的概念：Arduino引脚，PinName，STM32端口和引脚。

Arduino引脚：数字编号（0-10…）或重新定义的宏（PA1，PA2…）

PinName：封装了STM32的端口和引脚信息

STM32端口和引脚：具体的STM32芯片的端口（GPIOx）和引脚（GPIO_PIN_x）

宏函数：通过查表将Arduino引脚号转化为对STM32端口和引脚编码的PinName。

// Convert a digital pin number Dxx to a PinName PX_n

// Note: Analog pin is also a digital pin.

#define digitalPinToPinName(p)      (((uint32_t)p < NUM_DIGITAL_PINS) ? digitalPin[p] : NC)