stm32f407使用I2C2驱动PCA9685产生16通道PWM的代码

以下是使用STM32F407的I2C2驱动PCA9685产生16通道PWM的代码示例：

#include "stm32f4xx.h"

#define PCA9685_ADDRESS 0x80   // PCA9685 I2C address

// PCA9685 Registers
#define MODE1 0x00
#define PRESCALE 0xFE
#define LED0_ON_L 0x06

I2C_HandleTypeDef hi2c2;

void PCA9685_Init(void)
{
  uint8_t data[2];

  // Set the MODE1 register to put the PCA9685 in sleep mode
  data[0] = MODE1;
  data[1] = 0x10; // Sleep mode
  HAL_I2C_Master_Transmit(&hi2c2, PCA9685_ADDRESS, data, 2, 100);

  // Set the prescaler to generate a 50Hz PWM frequency
  data[0] = PRESCALE;
  data[1] = 0x79; // Prescaler value for 50Hz
  HAL_I2C_Master_Transmit(&hi2c2, PCA9685_ADDRESS, data, 2, 100);

  // Set the MODE1 register to restart the PCA9685
  data[0] = MODE1;
  data[1] = 0x00; // Restart
  HAL_I2C_Master_Transmit(&hi2c2, PCA9685_ADDRESS, data, 2, 100);
}

void PCA9685_SetPWM(uint8_t channel, uint16_t on_time, uint16_t off_time)
{
  uint8_t data[5];

  // Set the ON time for the specified channel
  data[0] = LED0_ON_L + 4 * channel;
  data[1] = on_time & 0xFF;
  data[2] = on_time >> 8;
  HAL_I2C_Master_Transmit(&hi2c2, PCA9685_ADDRESS, data, 3, 100);

  // Set the OFF time for the specified channel
  data[0] = LED0_ON_L + 4 * channel + 2;
  data[1] = off_time & 0xFF;
  data[2] = off_time >> 8;
  HAL_I2C_Master_Transmit(&hi2c2, PCA9685_ADDRESS, data, 3, 100);
}

int main(void)
{
  // Initialize the I2C2 peripheral
  hi2c2.Instance = I2C2;
  hi2c2.Init.ClockSpeed = 400000;
  hi2c2.Init.DutyCycle = I2C_DUTYCYCLE_2;
  hi2c2.Init.OwnAddress1 = 0;
  hi2c2.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
  hi2c2.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
  hi2c2.Init.OwnAddress2 = 0;
  hi2c2.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
  hi2c2.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
  HAL_I2C_Init(&hi2c2);

  // Initialize the PCA9685
  PCA9685_Init();

  // Set the PWM values for channels 0-15
  PCA9685_SetPWM(0, 0, 4095);   // Channel 0 full on
  PCA9685_SetPWM(1, 0, 2047);   // Channel 1 half on
  PCA9685_SetPWM(2, 2047, 0);   // Channel 2 half off
  // ...

  while (1)
  {
    // Main loop
  }
}

在此示例中，我们使用STM32F407的I2C2外设来驱动PCA9685芯片，以产生16个通道的PWM信号。首先，我们需要定义PCA9685芯片的I2C地址以及其寄存器地址。然后，我们定义了两个函数，PCA9685_Init()和PCA9685_SetPWM()，用于初始化PCA9685芯片并设置PWM输出。在主函数中，我们首先初始化I2C2外设，然后调用PCA9685_Init()函数以初始化PCA9685芯片。最后，我们调用PCA9685_SetPWM()函数来设置16个PWM通道的输出。

请注意，此示例中使用的PWM频率为50Hz，可以根据需要进行更改。此外，我们只设置了前三个PWM通道的输出，您可以根据需要设置其他通道的输出。