beta.h

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 *
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/**
 * @file    beta.h
 * @author  foxBMS Team
 * @date    2020-01-17 (date of creation)
 * @updated 2021-02-24 (date of last update)
 * @ingroup TEMPERATURE_SENSORS
 * @prefix  BETA
 *
 * @brief   Resistive divider used for measuring temperature
 *
 *          V_supply
 *            --.--
 *              |
 *            +-.-+
 *            |   |
 *            |   |  R_1
 *            |   |
 *            +-.-+
 *              |
 *              .--- V_adc
 *              |
 *            +-.-+
 *            |   |
 *            |   |  R_2
 *            |   |
 *            +-.-+
 *              |
 *            --.--
 *             GND
 *
 */
 
#ifndef FOXBMS__BETA_H_
#define FOXBMS__BETA_H_
 
/*========== Includes =======================================================*/
#include "general.h"
 
/*========== Macros and Definitions =========================================*/
/**
 * Position of the NTC in the voltage resistor
 * true: NTC is positioned above the voltage tap for the ADC voltage.
 * This equals resistor R_1 in the above circuit diagram
 *
 * false: NTC is positioned below the voltage tap for the ADC voltage.
 * This equals resistor R2 in the above circuit diagram
 */
#define BETA_POSITION_IN_RESISTOR_DIVIDER_IS_R_1 (false)
 
/** Resistor divider supply voltage in volt */
#define BETA_RESISTOR_DIVIDER_SUPPLY_VOLTAGE_V (4.096f)
 
/**
 * Resistance value of the other resistor (not the NTC) in the resistor
 * divider in kOhm.
 */
#define BETA_RESISTOR_DIVIDER_RESISTANCE_R_1_R_2_Ohm (10000.0f)
 
/** Reference temperature */
#define BETA_T_REF_C (25.0f)
 
/** NTC resistance at reference temperature */
#define BETA_R_REF_Ohm (10000.0f)
 
/** BEta coefficient of the NTC */
#define BETA_BETACOEFFICIENT (3984.0f)
 
/*========== Extern Constant and Variable Declarations ======================*/
 
/*========== Extern Function Prototypes =====================================*/
/**
 * @brief   returns temperature based on measured ADC voltage
 * @param   adcVoltage_mV   voltage in mV
 * @return  corresponding temperature in deci °C or FLT_MAX/FLT_MIN if NTC
 *          is shorted or got disconnected. The caller of this functions needs
 *          to check for these return values to prevent invalid data.
 */
extern int16_t BETA_GetTemperatureFromBeta(uint16_t adcVoltage_mV);
 
/**
 * @brief   returns temperature corresponding to NTC resistance
 * @param   resistance_Ohm  resistance in Ohm
 * @return  corresponding temperature in deci °C
 *
 */
extern int16_t BETA_TemperatureFromResistance(float resistance_Ohm);
 
/**
 * @brief   returns NTC resistance corresponding to temperature,
 *          used to compute Vmin and Vmax of the divider
 * @param   temperature_ddegC in deci °C
 * @return  corresponding resistance in Ohm
 *
 */
extern float BETA_ResistanceFromTemperature(int16_t temperature_ddegC);
 
/*========== Externalized Static Functions Prototypes (Unit Test) ===========*/
 
#endif /* FOXBMS__BETA_H_ */