rt-thread i2c 使用教程

rt-thread i2c 使用教程

rt-thread studio

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1. 创建基础工程

使用芯片级的基础工程作为环境。

2. 配置i2c

打开i2c。

配置驱动。

CTRL+S保存配置后，会重新生成工程。

修改board.h文件。取消 BSP_USING_I2C1 的注释。

/** if you want to use i2c bus(soft simulate) you can use the following instructions.
 *
 * STEP 1, open i2c driver framework(soft simulate) support in the RT-Thread Settings file
 *
 * STEP 2, define macro related to the i2c bus
 *                 such as     #define BSP_USING_I2C1
 *
 * STEP 3, according to the corresponding pin of i2c port, modify the related i2c port and pin information
 *                 such as     #define BSP_I2C1_SCL_PIN    GET_PIN(port, pin)   ->   GET_PIN(C, 11)
 *                             #define BSP_I2C1_SDA_PIN    GET_PIN(port, pin)   ->   GET_PIN(C, 12)
 */

#define BSP_USING_I2C1
#ifdef BSP_USING_I2C1
#define BSP_I2C1_SCL_PIN    GET_PIN(B, 10)
#define BSP_I2C1_SDA_PIN    GET_PIN(B, 11)
#endif

3. 代码

使用i2c 读取BMP280温湿度计。使用rt_i2c_transfer来读取和写入数据到传感器芯片。这里的温湿度驱动是我自己实现的。

#include <rtthread.h>
#include <rtdevice.h>
#include <stdio.h>
#include "bme280_i2c.h"

#define BMP280_I2C_BUS_NAME       "i2c1"
#define BME280_ADDR               0X76

static struct rt_i2c_bus_device *i2c_bus = RT_NULL;
static rt_bool_t initialized = RT_FALSE;

static int write_bytes(struct rt_i2c_bus_device *bus, uint8_t slave_addr, uint8_t reg_addr, uint8_t *data, uint8_t len)
{
    uint8_t buffer[128] = { 0 };
    buffer[0] = reg_addr;
    memcpy(buffer + 1, data, len);

    struct rt_i2c_msg msgs;
    msgs.addr = BME280_ADDR;
    msgs.flags = RT_I2C_WR;
    msgs.buf = buffer;
    msgs.len = len + 1;

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

static int read_bytes(struct rt_i2c_bus_device *bus, uint8_t slave_addr, uint8_t reg_addr, uint8_t *data, uint8_t len)
{
    struct rt_i2c_msg msgs[2];
    msgs[0].addr = BME280_ADDR;
    msgs[0].flags = RT_I2C_WR;
    msgs[0].buf = &reg_addr;
    msgs[0].len = 1;

    msgs[1].addr = BME280_ADDR;
    msgs[1].flags = RT_I2C_RD;
    msgs[1].buf = data;
    msgs[1].len = len;

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

static int write(uint8_t slave_addr, uint8_t reg_addr, uint8_t *bytes, uint32_t len)
{
    return write_bytes(i2c_bus, BME280_ADDR, reg_addr, bytes, len);
}

static int read(uint8_t slave_addr, uint8_t reg_addr, uint8_t *bytes, uint32_t len)
{
    return read_bytes(i2c_bus, BME280_ADDR, reg_addr, bytes, len);
}

static void delay_us(uint32_t us)
{
    rt_thread_mdelay(us / 1000);
}

static int i2c_test(void)
{
    i2c_bus = (struct rt_i2c_bus_device *) rt_device_find(BMP280_I2C_BUS_NAME);
    if (i2c_bus == RT_NULL)
    {
        rt_kprintf("can't find %s device!\n", BMP280_I2C_BUS_NAME);
        return RT_ERROR;
    }

    bme280_init(write, read, delay_us, NULL, 0);
    int32_t temperature = 0;
    bme280_read_temperature(&temperature);
    rt_kprintf("temp: %d\n", temperature);

    return RT_EOK;
}

MSH_CMD_EXPORT(i2c_test, i2c test);

4. 测试

使用i2c_test 进行demo测试，读取温度为27.28℃。

KEIL

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暂时无。