i2c 读写

在Ｉ２Ｃ设备读取，必须是在同一个周期内。

一个例子，可以同时读出两个值

int read_register_double_value(int reg_addr, unsigned char *value_h, unsigned char *value_l)
{
struct i2c_rdwr_ioctrl_data io_data = {0};
struct i2c_msg msg[2] = {{0}};
unsigned char data = 0;
unsigned char out[2] = {0};

data = red_addr;
msg[0].addr = i2c_addr;
msg[0].len=1;
msg[0].buf = &data;
msg[0].addr = i2c_addr;
msg[0].flags = I2C_M_RD;
msg[0].len = 2;
msg[0].buf = &out[0]

io_data.nmsg2 = 2;
io_data,msgs = &msg[0];

ret = ioctrl(devide_id, I2C_RDWR, &io_data);

*value_h = out[0];
*value_l = out[1];
}

在uboot中调试i2c，很实用。

i2c dev 0//悬着i2c设备总线

i2c probe 56 //查看地址５６是否是i2c设备

i2c md 56 0 1 //向设备中写数据

。。。