int8_t I2C_write(uint8_t addr, uint8_t reg_addr, const uint8_t* data, uint8_t len)  // packet function
) |/ E0 G* ~  i1 {; x  U- ~2 b{
    HAL_StatusTypeDef  status =HAL_OK;
    uint16_t deviceWriteAddr = (addr << 1);    //7 bit write address shall be pre-processed
  g5 X( G0 `" y% J' m$ k    status = HAL_I2C_Mem_Write(&hi2c1,deviceWriteAddr,(uint16_t)reg_addr,1,(uint8_t*)data,(uint16_t)len,I2C_READ_TIMEOUT);
6 U+ N8 U) j$ g9 \1 }    if (HAL_OK != status)
  Z. x% z9 ~$ d: n* z& _    {
" N. a+ L' Q3 K) ?" t4 ?% m        printf("I2C Write Fail:%d\n\r",status);
6 E4 q6 j; A* f+ d        return status;
    }
    return HAL_OK;
  d" Z. d5 B* R0 j9 Q}
* X1 ~5 U  n; P1 a, U
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;
" [1 d7 q# A- m% U   uint16_t deviceWriteAddr = addr << 1; //7 bit write address shall be pre-processed
      uint16_t deviceReadAddr = (addr << 1)|0x01;   //7 bit read address shall be pre-processed   
) g* E5 S2 E3 D2 z   uint8_t regAddr = reg_addr;
3 V# L  W2 g9 l* y8 w7 W. j         
status = HAL_I2C_Master_Transmit(&hi2c1,deviceWriteAddr,&regAddr,1,I2C_READ_TIMEOUT);
5 _7 D+ S9 g- Y8 z   
if (HAL_OK != status)
    {
: s2 \5 i6 E$ m3 p( V1 F        printf("I2C readreg Fail:%d\n\r",status);
        return status;
; A4 v. e. \' E5 w# e    }   

2 h  A+ u% c) p+ a    status = HAL_I2C_Master_Receive(&hi2c1,deviceReadAddr,(uint8_t*)data,(uint16_t)len,I2C_READ_TIMEOUT); //
4 k; v. H: o: d: }/ ^# o( i    if (HAL_OK != status)
2 t; L% \: ]" ?& H" F    {
& H) |9 E# J% o4 f0 s        printf("I2C Read1 Fail:%d\n\r",status);
        return status;
9 D+ r5 C& c! R. K5 g9 g9 G& f' q    }
% n6 w: T# ^6 u9 W& p    return HAL_OK;
1 u$ D4 m* o2 G" n- U }

写是用HAL_I2C_Mem_Write（) 重新打包；
读操作原本要用HAL_I2C_Mem_Read，发现多字节request时，返回 I2C error.
) L/ s5 t6 x! V. W如上改过后，单字节，多字节 读写稳定。
HAL_I2C_Mem_Write/HAL_I2C_Mem_Read 都是cubeMX 工具生成的HAL库。
2 m* o( \& N+ m9 \我是在STM32L4系列使用的。
6 A! m( `) k4 E) x/ a我参考的I2C 协议参考：http://www.cnblogs.com/aaronLinux/p/6218660.html