RT thread I2C tutorial

rt-thread i2c Use the tutorial

rt-thread studio

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1. Create basic engineering

Use chip level basic engineering as the environment .

2. To configure i2c

open i2c.

Configure driver .

CTRL+S After saving the configuration , The project will be regenerated .

modify board.h file . Cancel BSP_USING_I2C1 Notes .

/** 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. Code

Use i2c Read BMP280 Temperature and humidity meter . Use rt_i2c_transfer To read and write data to the sensor chip . The temperature and humidity drive here is implemented by myself .

#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. test

Use i2c_test Conduct demo test , The reading temperature is 27.28℃.

KEIL

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Temporarily none .