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 = {};
struct i2c_msg msg[] = {{}};
unsigned char data = ;
unsigned char out[] = {};
 
data = red_addr;
msg[].addr = i2c_addr;
msg[].len=;
msg[].buf = &data;
msg[].addr = i2c_addr;
msg[].flags = I2C_M_RD;
msg[].len = ;
msg[].buf = &out[]
 
io_data.nmsg2 = ;
io_data,msgs = &msg[];
 
ret = ioctrl(devide_id, I2C_RDWR, &io_data);
 
*value_h = out[];
*value_l = out[];
}

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

。。。