关于使用模拟i2c与pca9535pw第一次通讯时，发送失败

发布于 2024-07-05 20:04:01 浏览：330 订阅该版

在使用rtthread settings配置完i2c后，与pca9535pw的第一通讯报错，不知道为什么？代码如下：
main:

```c
    /* 初始化PCA9535PW */
    if (pca9535pw_init(I2C_BUS_NAME) != RT_EOK)
    {
        return 0;
    }
    rt_thread_delay(1000);
    while(pca9535pw_write_reg(PCA9535PW_CONFIG_PORT_0, 0x00) != RT_EOK)
    {
        rt_kprintf("Failed to configure Port 0\n");
    }
    while(pca9535pw_write_reg(PCA9535PW_CONFIG_PORT_1, 0x00) != RT_EOK)
    {
        rt_kprintf("Failed to configure Port 1\n");
    }
    while (1)
    {
        /* 打开特定引脚 */
        if (pca9535pw_write_reg(PCA9535PW_OUTPUT_PORT_0, 0x01) != RT_EOK)
        {
            rt_kprintf("Failed to write to Output Port 0\n");
        }
        if (pca9535pw_write_reg(PCA9535PW_OUTPUT_PORT_1, 0x06) != RT_EOK)
        {
            rt_kprintf("Failed to write to Output Port 1\n");
        }

rt_thread_mdelay(500);

/* 读取输入引脚状态 */
        if (pca9535pw_read_reg(PCA9535PW_INPUT_PORT_0, &value) == RT_EOK)
        {
            rt_kprintf("Input Port 0: 0x%02X\n", value);
        }
        else
        {
            rt_kprintf("Failed to read from Input Port 0\n");
        }

if (pca9535pw_read_reg(PCA9535PW_INPUT_PORT_1, &value) == RT_EOK)
        {
            rt_kprintf("Input Port 1: 0x%02X\n", value);
        }
        else
        {
            rt_kprintf("Failed to read from Input Port 1\n");
        }

rt_thread_mdelay(1000);
    }
```
pca9535pw.c:

```c
#include "pca9535pw.h"

#define PCA9535PW_ADDRESS   0x20    // PCA9535PW的I2C地址

static struct rt_i2c_bus_device *i2c_bus = RT_NULL;

/* 初始化I2C总线 */
rt_err_t pca9535pw_init(const char *i2c_bus_name)
{
    i2c_bus = (struct rt_i2c_bus_device *)rt_device_find(i2c_bus_name);
    if (i2c_bus == RT_NULL)
    {
        rt_kprintf("I2C bus %s not found!\n", i2c_bus_name);
        return -RT_ERROR;
    }

rt_kprintf("I2C bus %s found!\n", i2c_bus_name);
    return RT_EOK;
}

/* 写寄存器函数 */
rt_err_t pca9535pw_write_reg(rt_uint8_t reg, rt_uint8_t value)
{
    struct rt_i2c_msg msgs[2];
    rt_uint8_t buffer[2];

buffer[0] = reg;
    buffer[1] = value;

msgs[0].addr  = PCA9535PW_ADDRESS;
    msgs[0].flags = RT_I2C_WR;
    msgs[0].buf   = buffer;
    msgs[0].len   = 2;

if (rt_i2c_transfer(i2c_bus, msgs, 1) == 1)
    {
        return RT_EOK;
    }
    else
    {
        return -RT_ERROR;
    }
}

/* 读寄存器函数 */
rt_err_t pca9535pw_read_reg(rt_uint8_t reg, rt_uint8_t *value)
{
    struct rt_i2c_msg msgs[2];

msgs[0].addr  = PCA9535PW_ADDRESS;
    msgs[0].flags = RT_I2C_WR;
    msgs[0].buf   = ®
    msgs[0].len   = 1;

msgs[1].addr  = PCA9535PW_ADDRESS;
    msgs[1].flags = RT_I2C_RD;
    msgs[1].buf   = value;
    msgs[1].len   = 1;

if (rt_i2c_transfer(i2c_bus, msgs, 2) == 2)
    {
        return RT_EOK;
    }
    else
    {
        return -RT_ERROR;
    }
}

```