Unless your SHT20 is old, it supports two sets of commands. One uses SCL stretching, another does not. In the second case the device does not respond while busy. So just use the non-stretching commands and the usual HAL functions: HAL_I2C_Master_Transmit, HAL_I2C_Master_Receive etc.
Poll the device every N ms until it responds or you wait more than documented maximum (~ 100 ms, see in the data sheet)
The I2C address is 0x80.
// SHT20/25 commands:
typedef enum{
SHT2x_TRIG_T_MEASUREMENT_HM = 0xE3, // trig. temp meas. hold master
SHT2x_TRIG_RH_MEASUREMENT_HM = 0xE5, //trig. humidity meas. hold master
SHT2x_TRIG_T_MEASUREMENT_POLL = 0xF3, //trig. temp meas. no hold master <<<
SHT2x_TRIG_RH_MEASUREMENT_POLL = 0xF5, //trig. humidity meas. no hold master <<<
SHT2x_USER_REG_W = 0xE6, // writing user register
SHT2x_USER_REG_R = 0xE7, // reading user register
SHT2x_SOFT_RESET = 0xFE // soft reset
} eSHT2xCmd;
#define A_READ_TEMP_TMO 100 /* ms, max time from [DS, table 7] */
#define A_READ_RH_TMO 29 /* ms, max time from [DS, table 7] */
