pwm.c

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 *
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/**
 * @file    pwm.c
 * @author  foxBMS Team
 * @date    2021-10-07 (date of creation)
 * @updated 2021-10-08 (date of last update)
 * @ingroup DRIVERS
 * @prefix  PWM
 *
 * @brief   Implementation of the PWM module.
 *
 */
 
/*========== Includes =======================================================*/
#include "pwm.h"
 
#include "HL_etpwm.h"
 
#include "fsystem.h"
 
/*========== Macros and Definitions =========================================*/
/** lower threshold permill */
#define PWM_LOWER_THRESHOLD_PERM (1u)
 
/** upper threshold permill */
#define PWM_UPPER_THRESHOLD_PERM (999u)
 
/** full period in promill */
#define PWM_FULL_PERIOD_PERM (1000u)
 
/*========== Static Constant and Variable Definitions =======================*/
/** linear offset (through output circuit) */
static const int16_t pwm_kLinearOffset = 0;
 
/*========== Extern Constant and Variable Definitions =======================*/
 
/*========== Static Function Prototypes =====================================*/
/** returns the ePWM time period (currently for ePWM1A)
 * @returns ePWM time period in counter ticks
 */
static uint16_t PWM_GetEtpwmTimePeriod(void);
 
/** returns a ePWM counter value based on a duty cycle
 * @param[in]   dutyCycle_perm  duty cycle in permill
 * @returns     counter value
 */
static uint16_t PWM_ComputeCounterValueFromDutyCycle(uint16_t dutyCycle_perm);
 
/*========== Static Function Implementations ================================*/
static uint16_t PWM_GetEtpwmTimePeriod(void) {
    etpwm_config_reg_t etPwmConfig = {0};
    etpwm1GetConfigValue(&etPwmConfig, CurrentValue); /* retrieve the current config */
    return etPwmConfig.CONFIG_TBPRD;
}
 
static uint16_t PWM_ComputeCounterValueFromDutyCycle(uint16_t dutyCycle_perm) {
    FAS_ASSERT((dutyCycle_perm >= PWM_LOWER_THRESHOLD_PERM) && (dutyCycle_perm <= PWM_UPPER_THRESHOLD_PERM));
 
    uint16_t basePeriod   = PWM_GetEtpwmTimePeriod();
    uint32_t counterValue = (((uint32_t)basePeriod * (uint32_t)dutyCycle_perm) / PWM_FULL_PERIOD_PERM);
 
    FAS_ASSERT(counterValue <= (uint16_t)UINT16_MAX);
    return (uint16_t)counterValue;
}
 
/*========== Extern Function Implementations ================================*/
extern void PWM_StartPwm(void) {
    /* go to privileged mode in order to access control register */
    FAS_ASSERT(FSYS_RaisePrivilege() == 0);
    etpwmStartTBCLK();
    /* done; go back to user mode */
    FSYS_SwitchToUserMode();
}
 
extern void PWM_StopPwm(void) {
    /* go to privileged mode in order to access control register */
    FAS_ASSERT(FSYS_RaisePrivilege() == 0);
    etpwmStopTBCLK();
    /* done; go back to user mode */
    FSYS_SwitchToUserMode();
}
 
extern void PWM_SetDutyCycle(uint16_t dutyCycle_perm) {
    FAS_ASSERT(dutyCycle_perm <= (uint16_t)INT16_MAX);
    int16_t intermediateDutyCycle_perm = (int16_t)dutyCycle_perm + pwm_kLinearOffset;
    /* prevent wrap-around */
    if (intermediateDutyCycle_perm < 0) {
        intermediateDutyCycle_perm = 0;
    }
    uint16_t correctedDutyCycle_perm = (uint16_t)intermediateDutyCycle_perm;
 
    if (correctedDutyCycle_perm < PWM_LOWER_THRESHOLD_PERM) {
        correctedDutyCycle_perm = PWM_LOWER_THRESHOLD_PERM;
    }
 
    if (correctedDutyCycle_perm > PWM_UPPER_THRESHOLD_PERM) {
        correctedDutyCycle_perm = PWM_UPPER_THRESHOLD_PERM;
    }
 
    etpwmSetCmpA(etpwmREG1, PWM_ComputeCounterValueFromDutyCycle(correctedDutyCycle_perm));
}
 
/*========== Getter for static Variables (Unit Test) ========================*/
#ifdef UNITY_UNIT_TEST
extern int16_t TEST_PWM_GetLinearOffset(void) {
    return pwm_kLinearOffset;
}
#endif
 
/*========== Externalized Static Function Implementations (Unit Test) =======*/