/**
  * @brief get STM32g0x0 CPU temperature using fixpoint
  * @param[in]
  * @param[out]     none
  * @retval         temperature in 1/10°Celsius
  * @Author         Klaus Mezger
*/
uint16_t ecGetCPUTemp(uint16_t ADCvalue)
{

/* Tested with STM32G070 and g030.
 * This routine is fast because of using fixoint arithmetic.
 * Works without TS_CAL2, because this is not mentioned in the datasheets of STM32G030 and g070.
 * Even with using TS_CAL2 from STM32g031 / g071 you do possibly not get better results
 *
*/ 

 /* 130° and 30°C values from STM32G031 / STM32G071 */
    #define TEMP30_CAL  *(uint16_t*) 0x1FFF75A8
    #define TEMP130_CAL *(uint16_t*) 0x1FFF75CA //Not existent in STM32G0x0 DS, used here as test reference
    #define REF_TEMP 30         //calibration from datasheet

    /* decimal fixpoint d.1 */
    #define SLOPE_Y         25  //10*mV /°C from datasheet
    #define SLOPE_Y_INV     (int32_t)(100000/SLOPE_Y) //10 * inverse of slope
    #define VDDA_10d1       33  //VDDA 3.3V
    #define VREF_CAL_10d1   30  //VDDA 3.0V reference used in factory TS_CALx values

    uint32_t cal30;
    int16_t temp_10d1;  //resulting temperature
    int32_t adc_0;

    /* calc 30°C reference using VDDA 3.3V */
    cal30 = (TEMP30_CAL * VREF_CAL_10d1 /  VDDA_10d1);                  //ADC at 30° @ VDDA = 3.3V

    /* calc ADC value @ 0°C using typical TS slope from datasheet */
    adc_0 =  cal30 - ((REF_TEMP * SLOPE_Y << 12) / VDDA_10d1) / 1000;   //calculate offset @ 0°C

    /* calculate temperature based on TS offset @ 0°C */
    temp_10d1 = (ADCvalue - adc_0) * ((SLOPE_Y_INV * VDDA_10d1) >> 12) / 10; // skip last digit
  
    // original formula needs float temp = ((130-30)/(TS_CAL2 - TS_CAL1)) * (TS_DATA * TS_CAL1) + 30
    return temp_10d1;
}