stm32f407硬件i2c1控制pca9685的代码

以下是基于HAL库的STM32F407硬件I2C1控制PCA9685的代码示例：

#include "stm32f4xx_hal.h"

#define PCA9685_ADDRESS 0x40

I2C_HandleTypeDef hi2c1;

void PCA9685_Write(I2C_HandleTypeDef *hi2c, uint8_t reg, uint8_t *data, uint16_t size)
{
    while (HAL_I2C_Master_Transmit(hi2c, PCA9685_ADDRESS << 1, &reg, 1, HAL_MAX_DELAY) != HAL_OK);
    while (HAL_I2C_Master_Transmit(hi2c, PCA9685_ADDRESS << 1, data, size, HAL_MAX_DELAY) != HAL_OK);
}

void PCA9685_SetPWM(I2C_HandleTypeDef *hi2c, uint8_t channel, uint16_t on_time, uint16_t off_time)
{
    uint8_t data[4];
    data[0] = on_time & 0xFF;
    data[1] = on_time >> 8;
    data[2] = off_time & 0xFF;
    data[3] = off_time >> 8;
    PCA9685_Write(hi2c, 0x06 + 4 * channel, data, sizeof(data));
}

void PCA9685_SetFrequency(I2C_HandleTypeDef *hi2c, uint16_t frequency)
{
    uint8_t prescale = (uint8_t)((25000000.0f / (4096 * frequency)) - 1);
    PCA9685_Write(hi2c, 0xFE, &prescale, 1);
}

int main(void)
{
    HAL_Init();

    __HAL_RCC_I2C1_CLK_ENABLE();
    GPIO_InitTypeDef GPIO_InitStruct = {0};
    GPIO_InitStruct.Pin = GPIO_PIN_6 | GPIO_PIN_7;
    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);

    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;
    HAL_I2C_Init(&hi2c1);

    PCA9685_SetFrequency(&hi2c1, 50);
    PCA9685_SetPWM(&hi2c1, 0, 0, 4095); // Set channel 0 to full brightness
    PCA9685_SetPWM(&hi2c1, 1, 0, 2048); // Set channel 1 to half brightness

    while (1)
    {
        // Main loop
    }
}

这个例子中，我们使用了I2C1总线，PB6和PB7引脚作为I2C数据和时钟线。PCA9685的I2C地址是0x40。我们设置了频率为50Hz，并设置了通道0和通道1的PWM输出。可以根据实际需求修改频率和PWM输出的值。