I2C

Collaboration diagram for I2C:

Data Structures
struct	rt_i2c_priv_data
struct	rt_i2c_msg
struct	rt_i2c_bus_device_ops
struct	rt_i2c_bus_device
struct	rt_i2c_client

Macros
#define	RT_I2C_WR   0x0000
#define	RT_I2C_RD   (1u << 0)
#define	RT_I2C_ADDR_10BIT   (1u << 2)
#define	RT_I2C_NO_START   (1u << 4)
#define	RT_I2C_IGNORE_NACK   (1u << 5)
#define	RT_I2C_NO_STOP   (1u << 7)

Functions
rt_err_t	rt_i2c_bus_device_device_init (struct rt_i2c_bus_device *bus, const char *name)
rt_err_t	rt_i2c_bus_device_register (struct rt_i2c_bus_device *bus, const char *bus_name)
struct rt_i2c_bus_device *	rt_i2c_bus_device_find (const char *bus_name)
rt_ssize_t	rt_i2c_transfer (struct rt_i2c_bus_device *bus, struct rt_i2c_msg msgs[], rt_uint32_t num)
rt_err_t	rt_i2c_control (struct rt_i2c_bus_device *bus, int cmd, void *args)
rt_ssize_t	rt_i2c_master_send (struct rt_i2c_bus_device *bus, rt_uint16_t addr, rt_uint16_t flags, const rt_uint8_t *buf, rt_uint32_t count)
rt_ssize_t	rt_i2c_master_recv (struct rt_i2c_bus_device *bus, rt_uint16_t addr, rt_uint16_t flags, rt_uint8_t *buf, rt_uint32_t count)

Detailed Description

I2C driver api.

Example

#include <rtthread.h>
#include <rtdevice.h>
 
#define AHT10_I2C_BUS_NAME          "i2c1"  // 传感器连接的I2C总线设备名称
#define AHT10_ADDR                  0x38    // 从机地址
#define AHT10_CALIBRATION_CMD       0xE1    // 校准命令
#define AHT10_NORMAL_CMD            0xA8    // 一般命令
#define AHT10_GET_DATA              0xAC    // 获取数据命令
 
static struct rt_i2c_bus_device *i2c_bus = RT_NULL;     // I2C总线设备句柄
static rt_bool_t initialized = RT_FALSE;                // 传感器初始化状态
 
// 写传感器寄存器
static rt_err_t write_reg(struct rt_i2c_bus_device *bus, rt_uint8_t reg, rt_uint8_t *data)
{
    rt_uint8_t buf[3];
    struct rt_i2c_msg msgs;
    rt_uint32_t buf_size = 1;
 
    buf[0] = reg; //cmd
    if (data != RT_NULL)
    {
        buf[1] = data[0];
        buf[2] = data[1];
        buf_size = 3;
    }
 
    msgs.addr = AHT10_ADDR;
    msgs.flags = RT_I2C_WR;
    msgs.buf = buf;
    msgs.len = buf_size;
 
    // 调用I2C设备接口传输数据
    if (rt_i2c_transfer(bus, &msgs, 1) == 1)
    {
        return RT_EOK;
    }
    else
    {
        return -RT_ERROR;
    }
}
 
// 读传感器寄存器数据
static rt_err_t read_regs(struct rt_i2c_bus_device *bus, rt_uint8_t len, rt_uint8_t *buf)
{
    struct rt_i2c_msg msgs;
 
    msgs.addr = AHT10_ADDR;
    msgs.flags = RT_I2C_RD;
    msgs.buf = buf;
    msgs.len = len;
 
    // 调用I2C设备接口传输数据
    if (rt_i2c_transfer(bus, &msgs, 1) == 1)
    {
        return RT_EOK;
    }
    else
    {
        return -RT_ERROR;
    }
}
 
static void read_temp_humi(float *cur_temp, float *cur_humi)
{
    rt_uint8_t temp[6];
 
    write_reg(i2c_bus, AHT10_GET_DATA, RT_NULL);      // 发送命令
    rt_thread_mdelay(400);
    read_regs(i2c_bus, 6, temp);                // 获取传感器数据
 
    // 湿度数据转换
    *cur_humi = (temp[1] << 12 | temp[2] << 4 | (temp[3] & 0xf0) >> 4) * 100.0 / (1 << 20);
    // 温度数据转换
    *cur_temp = ((temp[3] & 0xf) << 16 | temp[4] << 8 | temp[5]) * 200.0 / (1 << 20) - 50;
}
 
static void aht10_init(const char *name)
{
    rt_uint8_t temp[2] = {0, 0};
 
    // 查找I2C总线设备，获取I2C总线设备句柄
    i2c_bus = (struct rt_i2c_bus_device *)rt_device_find(name);
 
    if (i2c_bus == RT_NULL)
    {
        rt_kprintf("can't find %s device!\n", name);
    }
    else
    {
        write_reg(i2c_bus, AHT10_NORMAL_CMD, temp);
        rt_thread_mdelay(400);
 
        temp[0] = 0x08;
        temp[1] = 0x00;
        write_reg(i2c_bus, AHT10_CALIBRATION_CMD, temp);
        rt_thread_mdelay(400);
        initialized = RT_TRUE;
    }
}
 
static void i2c_aht10_sample(int argc, char *argv[])
{
    float humidity, temperature;
    char name[RT_NAME_MAX];
 
    humidity = 0.0;
    temperature = 0.0;
 
    if (argc == 2)
    {
        rt_strncpy(name, argv[1], RT_NAME_MAX);
    }
    else
    {
        rt_strncpy(name, AHT10_I2C_BUS_NAME, RT_NAME_MAX);
    }
 
    if (!initialized)
    {
        // 传感器初始化
        aht10_init(name);
    }
    if (initialized)
    {
        // 读取温湿度数据
        read_temp_humi(&temperature, &humidity);
 
        rt_kprintf("read aht10 sensor humidity   : %d.%d %%\n", (int)humidity, (int)(humidity * 10) % 10);
        if( temperature >= 0 )
        {
            rt_kprintf("read aht10 sensor temperature: %d.%d°C\n", (int)temperature, (int)(temperature * 10) % 10);
        }
        else
        {
            rt_kprintf("read aht10 sensor temperature: %d.%d°C\n", (int)temperature, (int)(-temperature * 10) % 10);
        }
    }
    else
    {
        rt_kprintf("initialize sensor failed!\n");
    }
}
// 导出到 msh 命令列表中
MSH_CMD_EXPORT(i2c_aht10_sample, i2c aht10 sample);

Macro Definition Documentation

RT_I2C_WR

#define RT_I2C_WR   0x0000

i2c wirte flag

RT_I2C_RD

#define RT_I2C_RD   (1u << 0)

i2c read flag

RT_I2C_ADDR_10BIT

#define RT_I2C_ADDR_10BIT   (1u << 2)

this is a ten bit chip address

RT_I2C_NO_START

#define RT_I2C_NO_START   (1u << 4)

do not generate START condition

RT_I2C_IGNORE_NACK

#define RT_I2C_IGNORE_NACK   (1u << 5)

ignore NACK from slave

RT_I2C_NO_STOP

#define RT_I2C_NO_STOP   (1u << 7)

do not generate STOP condition

Function Documentation

rt_i2c_bus_device_device_init()

rt_err_t rt_i2c_bus_device_device_init	(	struct rt_i2c_bus_device *	bus,
		const char *	name )

I2C Bus Device Initialization.

Parameters

bus	the I2C bus device
name	the name of I2C bus device

Returns

rt_err_t error code

rt_i2c_bus_device_register()

rt_err_t rt_i2c_bus_device_register	(	struct rt_i2c_bus_device *	bus,
		const char *	bus_name )

I2C Bus Device Register.

Parameters

bus	the I2C bus device
bus_name	the name of I2C bus device

Returns

rt_err_t error code

rt_i2c_bus_device_find()

struct rt_i2c_bus_device * rt_i2c_bus_device_find

(

const char *

bus_name

)

I2C Bus Device Find.

Parameters

bus_name

the name of I2C bus device

Returns

rt_i2c_bus_device the I2C bus device

rt_i2c_transfer()

rt_ssize_t rt_i2c_transfer	(	struct rt_i2c_bus_device *	bus,
		struct rt_i2c_msg	msgs[],
		rt_uint32_t	num )

I2C data transmission.

Parameters

bus	the I2C bus device
msgs	the I2C message list
num	the number of I2C message

Returns

rt_ssize_t the actual length of transmitted

rt_i2c_control()

rt_err_t rt_i2c_control	(	struct rt_i2c_bus_device *	bus,
		int	cmd,
		void *	args )

I2C Control.

Parameters

bus	the I2C bus device
cmd	the I2C control command
args	the I2C control arguments

Returns

rt_err_t error code

rt_i2c_master_send()

rt_ssize_t rt_i2c_master_send	(	struct rt_i2c_bus_device *	bus,
		rt_uint16_t	addr,
		rt_uint16_t	flags,
		const rt_uint8_t *	buf,
		rt_uint32_t	count )

I2C Master Send.

Parameters

bus	the I2C bus device
addr	the I2C slave address
flags	the I2C flags
buf	the I2C send buffer
count	the I2C send buffer length

Returns

rt_ssize_t the actual length of transmitted

rt_i2c_master_recv()

rt_ssize_t rt_i2c_master_recv	(	struct rt_i2c_bus_device *	bus,
		rt_uint16_t	addr,
		rt_uint16_t	flags,
		rt_uint8_t *	buf,
		rt_uint32_t	count )

I2C Master Receive.

Parameters

bus	the I2C bus device
addr	the I2C slave address
flags	the I2C flags
buf	the I2C receive buffer
count	the I2C receive buffer length

Returns

rt_ssize_t the actual length of received