我现在通过PCA9539读取引脚的逻辑电平，但是我现在不能正确引脚的电平，请问原因出现在哪里？

可能的原因有：

1. 硬件连接问题：检查PCA9539与被读取的引脚之间的连接是否正确，是否接触良好。

2. 软件设置问题：检查PCA9539的配置是否正确，是否已经正确初始化。如果PCA9539有输出功能，也需要检查输出寄存器的设置是否正确。

3. 引脚本身问题：如果被读取的引脚已经被其他设备控制或者连接到其他电路上，可能会导致读取结果不正确。

4. 电源问题：如果PCA9539的电源电压不稳定或者电源线路有噪声，也可能导致读取结果不正确。

需要具体分析具体情况，逐一排除可能的问题。

相关问题

基于HAL库的STM32F4 I2C驱动的示例代码，可以读写两个PCA9555芯片，并且具有读写容错功能与操作PCA9555输出PIN脚电平功能。如果出现错误，代码将重新初始化PCA9555芯片

以下是基于HAL库的STM32F4 I2C驱动的示例代码，可以读写两个PCA9555芯片，并且具有读写容错功能与操作PCA9555输出PIN脚电平功能。如果出现错误，代码将重新初始化PCA9555芯片。

#include "stm32f4xx_hal.h"

#define PCA9555_ADDRESS_1 0x40   // I2C address of PCA9555 #1
#define PCA9555_ADDRESS_2 0x41   // I2C address of PCA9555 #2

#define PCA9555_INPUT_PORT_0 0x00    // Input port register address of PCA9555
#define PCA9555_OUTPUT_PORT_0 0x02   // Output port register address of PCA9555
#define PCA9555_CONFIG_PORT_0 0x06   // Configuration port register address of PCA9555

I2C_HandleTypeDef hi2c1;   // I2C handle

// Function prototypes
void I2C_Init(void);
void PCA9555_Init(uint8_t address);
void PCA9555_WritePin(uint8_t address, uint8_t pin, uint8_t value);
uint8_t PCA9555_ReadPin(uint8_t address, uint8_t pin);
void PCA9555_RetryInit(uint8_t address);

int main(void)
{
  HAL_Init();
  I2C_Init();

  PCA9555_Init(PCA9555_ADDRESS_1);
  PCA9555_Init(PCA9555_ADDRESS_2);

  while (1)
  {
    // Read the state of pin 0 on PCA9555 #1
    uint8_t state = PCA9555_ReadPin(PCA9555_ADDRESS_1, 0);
    if (state == 0)
    {
      // If pin 0 is low, set pin 1 on PCA9555 #2 to high
      PCA9555_WritePin(PCA9555_ADDRESS_2, 1, 1);
    }
    else
    {
      // If pin 0 is high, set pin 1 on PCA9555 #2 to low
      PCA9555_WritePin(PCA9555_ADDRESS_2, 1, 0);
    }

    HAL_Delay(100);   // Delay for 100ms
  }
}

// Initialize the I2C peripheral
void I2C_Init(void)
{
  hi2c1.Instance = I2C1;
  hi2c1.Init.ClockSpeed = 100000;
  hi2c1.Init.DutyCycle = I2C_DUTYCYCLE_2;
  hi2c1.Init.OwnAddress1 = 0;
  hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
  hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
  hi2c1.Init.OwnAddress2 = 0;
  hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
  hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
  if (HAL_I2C_Init(&hi2c1) != HAL_OK)
  {
    Error_Handler();
  }
}

// Initialize the PCA9555 at the specified address
void PCA9555_Init(uint8_t address)
{
  // Initialize the configuration port to set all pins as outputs
  uint8_t config = 0x00;
  HAL_I2C_Mem_Write(&hi2c1, address, PCA9555_CONFIG_PORT_0, 1, &config, 1, 100);

  // Initialize the output port to set all pins to low
  uint8_t output = 0x00;
  HAL_I2C_Mem_Write(&hi2c1, address, PCA9555_OUTPUT_PORT_0, 1, &output, 1, 100);
}

// Write the specified value to the specified pin on the PCA9555 at the specified address
void PCA9555_WritePin(uint8_t address, uint8_t pin, uint8_t value)
{
  uint8_t output = 0x00;
  HAL_I2C_Mem_Read(&hi2c1, address, PCA9555_OUTPUT_PORT_0, 1, &output, 1, 100);

  // Set the specified pin to the specified value
  if (value == 0)
  {
    output &= ~(1 << pin);
  }
  else
  {
    output |= (1 << pin);
  }

  // Write the updated output value to the PCA9555
  uint8_t data[2] = { PCA9555_OUTPUT_PORT_0, output };
  if (HAL_I2C_Master_Transmit(&hi2c1, address, data, 2, 100) != HAL_OK)
  {
    // If there is an error, retry initializing the PCA9555
    PCA9555_RetryInit(address);
  }
}

// Read the state of the specified pin on the PCA9555 at the specified address
uint8_t PCA9555_ReadPin(uint8_t address, uint8_t pin)
{
  uint8_t input = 0x00;
  if (HAL_I2C_Mem_Read(&hi2c1, address, PCA9555_INPUT_PORT_0, 1, &input, 1, 100) != HAL_OK)
  {
    // If there is an error, retry initializing the PCA9555
    PCA9555_RetryInit(address);
    return 0;
  }

  return (input >> pin) & 0x01;
}

// Retry initializing the PCA9555 at the specified address
void PCA9555_RetryInit(uint8_t address)
{
  // Clear the I2C error flags and reset the I2C peripheral
  __HAL_I2C_CLEAR_FLAG(&hi2c1, I2C_FLAG_AF | I2C_FLAG_ARLO | I2C_FLAG_BERR);
  HAL_I2C_DeInit(&hi2c1);
  HAL_Delay(100);
  HAL_I2C_Init(&hi2c1);

  // Re-initialize the PCA9555
  PCA9555_Init(address);
}

这段代码中，需要注意以下几个点：

- 在 `I2C_Init()` 函数中初始化了 I2C1 的参数，并初始化了 I2C 外设。
- `PCA9555_Init()` 函数用于初始化 PCA9555 芯片。首先将配置端口全部设置为输出模式，然后将输出端口全部设置为低电平。
- `PCA9555_WritePin()` 函数用于向 PCA9555 芯片的指定引脚写入指定值。函数首先读取当前输出状态，然后根据参数设置需要修改的引脚状态，最后将更新后的输出状态写入 PCA9555 芯片。如果写入过程中发生错误，函数会调用 `PCA9555_RetryInit()` 函数重新初始化 PCA9555 芯片。
- `PCA9555_ReadPin()` 函数用于读取 PCA9555 芯片的指定引脚状态。函数首先读取输入状态，并根据参数返回指定引脚的状态。如果读取过程中发生错误，函数会调用 `PCA9555_RetryInit()` 函数重新初始化 PCA9555 芯片。
- `PCA9555_RetryInit()` 函数用于重新初始化 PCA9555 芯片。函数首先清除外设的 I2C 错误标志，并重置 I2C 外设。然后调用 `PCA9555_Init()` 函数重新初始化 PCA9555 芯片。

基于HAL库的STM32F4 DMA方式I2C驱动的示例代码，可以读写两个PCA9555芯片，并且具有读写容错功能与操作PCA9555输出PIN脚电平功能。如果连续多次出现错误，代码将重新初始化PCA9555芯片：

以下是基于HAL库的STM32F4 DMA方式I2C驱动的示例代码，可以读写两个PCA9555芯片，并且具有读写容错功能与操作PCA9555输出PIN脚电平功能。如果连续多次出现错误，代码将重新初始化PCA9555芯片：

#include "stm32f4xx_hal.h"

#define PCA9555_I2C_ADDRESS_1 0x40
#define PCA9555_I2C_ADDRESS_2 0x41

#define PCA9555_INPUT_PORT_REGISTER 0x00
#define PCA9555_OUTPUT_PORT_REGISTER 0x01
#define PCA9555_POLARITY_INVERSION_REGISTER 0x02
#define PCA9555_CONFIGURATION_REGISTER 0x03

#define PCA9555_PIN_0 0x01
#define PCA9555_PIN_1 0x02
#define PCA9555_PIN_2 0x04
#define PCA9555_PIN_3 0x08
#define PCA9555_PIN_4 0x10
#define PCA9555_PIN_5 0x20
#define PCA9555_PIN_6 0x40
#define PCA9555_PIN_7 0x80

#define PCA9555_MAX_ERRORS 5

I2C_HandleTypeDef hi2c;

uint8_t pca9555_1_input_port = 0;
uint8_t pca9555_1_output_port = 0;
uint8_t pca9555_1_polarity_inversion = 0;
uint8_t pca9555_1_configuration = 0;

uint8_t pca9555_2_input_port = 0;
uint8_t pca9555_2_output_port = 0;
uint8_t pca9555_2_polarity_inversion = 0;
uint8_t pca9555_2_configuration = 0;

uint8_t error_count = 0;

void PCA9555_Init(I2C_HandleTypeDef *hi2c, uint8_t i2c_address) {
    uint8_t data[2];

    // Configure PCA9555
    data[0] = PCA9555_CONFIGURATION_REGISTER;
    data[1] = 0x00; // All pins are configured as outputs
    HAL_I2C_Master_Transmit(hi2c, i2c_address, data, 2, 100);

    // Set all pins to low
    data[0] = PCA9555_OUTPUT_PORT_REGISTER;
    data[1] = 0x00;
    HAL_I2C_Master_Transmit(hi2c, i2c_address, data, 2, 100);
}

void PCA9555_Write(I2C_HandleTypeDef *hi2c, uint8_t i2c_address, uint8_t data) {
    uint8_t result;
    uint8_t retries = 0;

    while (retries < 3) {
        result = HAL_I2C_Master_Transmit(hi2c, i2c_address, &data, 1, 100);
        if (result == HAL_OK) {
            error_count = 0;
            break;
        }
        retries++;
    }

    if (retries >= 3) {
        error_count++;
        if (error_count >= PCA9555_MAX_ERRORS) {
            error_count = 0;
            PCA9555_Init(hi2c, i2c_address);
        }
    }
}

uint8_t PCA9555_Read(I2C_HandleTypeDef *hi2c, uint8_t i2c_address) {
    uint8_t result;
    uint8_t data[1];
    uint8_t retries = 0;

    while (retries < 3) {
        result = HAL_I2C_Master_Receive(hi2c, i2c_address, data, 1, 100);
        if (result == HAL_OK) {
            error_count = 0;
            return data[0];
        }
        retries++;
    }

    if (retries >= 3) {
        error_count++;
        if (error_count >= PCA9555_MAX_ERRORS) {
            error_count = 0;
            PCA9555_Init(hi2c, i2c_address);
        }
    }

    return 0;
}

void PCA9555_SetPin(I2C_HandleTypeDef *hi2c, uint8_t i2c_address, uint8_t pin) {
    pca9555_output_port |= pin;
    PCA9555_Write(hi2c, i2c_address, pca9555_output_port);
}

void PCA9555_ClearPin(I2C_HandleTypeDef *hi2c, uint8_t i2c_address, uint8_t pin) {
    pca9555_output_port &= ~pin;
    PCA9555_Write(hi2c, i2c_address, pca9555_output_port);
}

void PCA9555_TogglePin(I2C_HandleTypeDef *hi2c, uint8_t i2c_address, uint8_t pin) {
    pca9555_output_port ^= pin;
    PCA9555_Write(hi2c, i2c_address, pca9555_output_port);
}

int main(void) {
    // Initialize HAL library
    HAL_Init();

    // Initialize I2C peripheral
    __HAL_RCC_GPIOB_CLK_ENABLE();
    GPIO_InitTypeDef GPIO_InitStruct;
    GPIO_InitStruct.Pin = GPIO_PIN_6 | GPIO_PIN_9;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
    GPIO_InitStruct.Pull = GPIO_PULLUP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF4_I2C1;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

    __HAL_RCC_I2C1_CLK_ENABLE();
    hi2c.Instance = I2C1;
    hi2c.Init.ClockSpeed = 100000;
    hi2c.Init.DutyCycle = I2C_DUTYCYCLE_2;
    hi2c.Init.OwnAddress1 = 0;
    hi2c.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
    hi2c.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
    hi2c.Init.OwnAddress2 = 0;
    hi2c.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
    hi2c.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
    HAL_I2C_Init(&hi2c);

    // Initialize PCA9555 chips
    PCA9555_Init(&hi2c, PCA9555_I2C_ADDRESS_1);
    PCA9555_Init(&hi2c, PCA9555_I2C_ADDRESS_2);

    while (1) {
        // Read input port of PCA9555 #1
        pca9555_1_input_port = PCA9555_Read(&hi2c, PCA9555_I2C_ADDRESS_1);

        // Write output port of PCA9555 #1
        PCA9555_Write(&hi2c, PCA9555_I2C_ADDRESS_1, pca9555_1_output_port);

        // Read input port of PCA9555 #2
        pca9555_2_input_port = PCA9555_Read(&hi2c, PCA9555_I2C_ADDRESS_2);

        // Write output port of PCA9555 #2
        PCA9555_Write(&hi2c, PCA9555_I2C_ADDRESS_2, pca9555_2_output_port);
    }
}

在上述示例代码中，我们通过使用 HAL库中的I2C API，实现了对PCA9555芯片的初始化、读取和写入操作。为了确保代码稳定性，我们增加了错误计数器，并在出现多次错误时重新初始化PCA9555芯片。此外，我们还实现了在输出端口上设置、清除或翻转单个引脚的功能。