int8_t I2C_write(uint8_t addr, uint8_t reg_addr, const uint8_t* data, uint8_t len)  // packet function
{
    HAL_StatusTypeDef  status =HAL_OK;
4 G" z- ^7 p$ j* v    uint16_t deviceWriteAddr = (addr << 1);    //7 bit write address shall be pre-processed
    status = HAL_I2C_Mem_Write(&hi2c1,deviceWriteAddr,(uint16_t)reg_addr,1,(uint8_t*)data,(uint16_t)len,I2C_READ_TIMEOUT);
    if (HAL_OK != status)
    {
        printf("I2C Write Fail:%d\n\r",status);
* x2 N7 F# n% i/ ~# e' h  e9 R        return status;
5 `6 {: B* e3 T4 m    }
    return HAL_OK;
}

int8_t I2C_read(uint8_t addr, uint8_t reg_addr, const uint8_t* data, uint8_t len)  //re packet function
{
    HAL_StatusTypeDef  status =HAL_OK;
" |7 K4 |: X5 ?7 ^3 @   uint16_t deviceWriteAddr = addr << 1; //7 bit write address shall be pre-processed
4 m9 h) A+ |4 n      uint16_t deviceReadAddr = (addr << 1)|0x01;   //7 bit read address shall be pre-processed   
   uint8_t regAddr = reg_addr;
. i- Z1 n" Z: T) A( Q8 }8 A# L         
status = HAL_I2C_Master_Transmit(&hi2c1,deviceWriteAddr,&regAddr,1,I2C_READ_TIMEOUT);
   
if (HAL_OK != status)
$ |) R! o7 C4 f  W% e/ r    {
1 i2 Y8 O; @2 H+ o) o        printf("I2C readreg Fail:%d\n\r",status);
  I# S8 h8 V  b7 n0 d7 B        return status;
    }   
6 y9 \$ H' T8 Q7 R
    status = HAL_I2C_Master_Receive(&hi2c1,deviceReadAddr,(uint8_t*)data,(uint16_t)len,I2C_READ_TIMEOUT); //
    if (HAL_OK != status)
- `9 [! n$ k$ Y    {
        printf("I2C Read1 Fail:%d\n\r",status);
        return status;
! Y% j. p* I8 y  P4 D2 u9 N    }
, p- G3 [: L" n) a) u    return HAL_OK;
# C, e. n- ]9 r! d* k# r# }( n5 w }

写是用HAL_I2C_Mem_Write（) 重新打包；
9 N0 x: s+ X( D4 R2 i/ Z, }2 D& f读操作原本要用HAL_I2C_Mem_Read，发现多字节request时，返回 I2C error.
$ w' G. ~; P  v5 W1 |+ A/ B如上改过后，单字节，多字节 读写稳定。
& b. F3 c9 t6 aHAL_I2C_Mem_Write/HAL_I2C_Mem_Read 都是cubeMX 工具生成的HAL库。
- @9 x) S" E4 l9 M! L我是在STM32L4系列使用的。
3 H! G6 Y2 w% l我参考的I2C 协议参考：http://www.cnblogs.com/aaronLinux/p/6218660.html
2 |5 f- i4 Q+ F