charge_controller_MSPM0G3507/src/cc_cv_charging.c

#include "cc_cv_charging.h"
#include "src/config.h"
#include "src/battery_data/battery.h"
#include <stdio.h>
#include "ti/driverlib/dl_gpio.h"
#include "ti_msp_dl_config.h"
#include "src/controller/controller.h"

static ChargingState charging_state= STATE_IDLE;
static uint16_t cycle_count = 0;
// declaring static global variables to retain their values between multiple function calls till the end of the program
static uint16_t batt_voltage;
static int16_t batt_current;
static uint16_t batt_min_voltage;
static uint16_t batt_max_voltage;
static uint16_t batt_cutoff_current;
static uint16_t batt_capacitance;
static int16_t batt_charge_discharge;
// Functions for Charging and Discharging State

void CC_CV_UpdateChargingState(uint8_t slot_id) {
    //static variable to keep a log on the transition during charging and dischrging phases
    static ChargingState previous_state= STATE_IDLE;
    // Flag for CV charging, the charging mode flips back to CC mode
    static bool cv_charging_started = false;
    batt_voltage = battery_data[slot_id].battery_measurement.voltage;
    batt_current = battery_data[slot_id].battery_measurement.current;
    batt_min_voltage = battery_data[slot_id].min_voltage;
    batt_max_voltage = battery_data[slot_id].max_voltage;
    batt_cutoff_current = battery_data[slot_id].cut_off_current;
    batt_capacitance = battery_data[slot_id].capacitance;
    batt_charge_discharge= battery_data[slot_id].charge_discharge;
    

    //Log for transitions
    if(charging_state != previous_state){
        printf("State transition: %d -> %d\n", previous_state, charging_state);
        previous_state= charging_state;
    }

    //Check if the slot is empty or if the battery limits are not set
    if (battery_data[slot_id].battery_state == STATE_EMPTY || (batt_min_voltage == 0 && batt_max_voltage == 0 &&
         batt_cutoff_current== 0 && batt_capacitance== 0)) {
      charging_state = STATE_IDLE;
      return;
    }
    
    //Check if the battery is overcharged
    if (batt_voltage > batt_max_voltage) {
      charging_state = STATE_ERROR;
      return;
    }
  
    //1. Pre Charge: if the battery is deeply discharged
    if ((batt_voltage < batt_min_voltage)) {
      charging_state = STATE_PRE_CHARGE;
      cv_charging_started = false;
    }
    // 2. Fast Charging Condition: CC Charging: cv_charging_started condition
    // added to avoid toggling back to CC after CV state is reached
  
    else if (!cv_charging_started &&
             (batt_voltage >= batt_min_voltage) &&
             (batt_voltage < batt_max_voltage - BATTERY_THRESHOLD)) {
      charging_state = STATE_CC_CHARGING;
    }
    // 3. CV Charging condition: Changing the cv_charging_state to True, once the
    // CV mode is reached
  
    else if (batt_voltage >= batt_max_voltage - BATTERY_THRESHOLD) {
      charging_state = STATE_CV_CHARGING;
      cv_charging_started = true;
    }
  
    // 4. Cut-off check inside CV
  
    else if ((charging_state == STATE_CV_CHARGING) &&
             (batt_current <= batt_cutoff_current + BATTERY_THRESHOLD)) {
      if (cycle_count < MAX_CYCLES) {
        charging_state = STATE_DISCHARGING;
        cycle_count++;
      } else {
        charging_state = STATE_FINAL_DISCHARGE;
      }
    }
  
    // 5. State Discharging condition
  
    else if (charging_state == STATE_DISCHARGING &&
             batt_voltage <= batt_min_voltage + BATTERY_THRESHOLD) {
      DL_GPIO_clearPins(GPIO_Battery_Discharging_PORT, GPIO_Battery_Discharging_PIN_PB7_PIN);
      charging_state = STATE_CC_CHARGING;
      cv_charging_started = false;
    }
  
    // 6. Hold previous state if none of the condition matches (Previously,
    // CV_STATE was jumping directly to STATE_ERROR in else statement, to handle
    // the condition better, else condition is being changed).
    else {
      printf("[CC-CV] Current state: Voltage= %d mV, Current= %d mA\n",
             batt_voltage, batt_current);
    }
  }

  /*
Function for Battery Charging and Discharging:
** Pre Charge: Once the battery is in discharged state, pre-charging
begins. Starts charging safely with a typically low current C/10
** Constant Current: Continues until the battery voltage has reached the "full"
or floating voltage level
** Constant Voltage: CV voltage starts once the maximum
voltage threshold is obtained.
*/

void CC_CV_ControlCharging(uint8_t slot_id, int16_t charge_current) {
    // Calling function to get all the conditional states
    CC_CV_UpdateChargingState(slot_id);
    
    //batt_voltage = battery_data[slot_id].battery_measurement.voltage;
    //batt_current= battery_data[slot_id].battery_measurement.current;
    batt_min_voltage= battery_data[slot_id].min_voltage;
    batt_max_voltage= battery_data[slot_id].max_voltage;
    batt_cutoff_current = battery_data[slot_id].cut_off_current;
    batt_capacitance= battery_data[slot_id].capacitance;
    batt_charge_discharge= battery_data[slot_id].charge_discharge;
    
    //  DAC channel value:
    // dac_channel_value is for CV mode where the charge current is calibrated till battery current is less than (cutoff current+threshold)
    // Adding a variable to check the stepness in the voltage drop in CV charging
    // mode:
    static uint16_t last_voltage = 0;
    //flag for DAC: so that the dac value is initialized only once and then can be decremented rather than resetting to the initial value
    static bool dac_initialized= false;

    switch (charging_state) {
  
    // PRE CHARGE STATE: Battery Voltage is lesser than 3000 mVolts
    case STATE_PRE_CHARGE:
      //DL_GPIO_setPins(GPIO_Battery_Charging_PORT, GPIO_Battery_Charging_PIN_PB6_PIN);
      DL_GPIO_setPins(GPIO_Battery_Discharging_PORT, GPIO_Battery_Discharging_PIN_PB7_PIN);
      controller_SetCurrent(TARGET_MCU_ADDRESS, slot_id, charge_current);
      if (true) {
        printf("PRE CHARGING: Slot %d at %d mA.\n", slot_id, charge_current);
      }
      break;
  
    // CC CHARGING STATE: Keeps on checking the condition until battery voltage
    // reaches to (MAXIMUM_VOLTAGE-BATTERY_THRESHOLD)= 4150 mVolts
    case STATE_CC_CHARGING:
      DL_GPIO_setPins(GPIO_Battery_Discharging_PORT, GPIO_Battery_Discharging_PIN_PB7_PIN);
      controller_SetCurrent(TARGET_MCU_ADDRESS, slot_id, charge_current);
      printf("CC CHARGING: Slot %d, Current: %d mA, Voltage: %d mV.\n", slot_id, batt_current, batt_voltage);
      break;
  
    // CV CHARGING STATE: Keeps on checking the condition until battery current
    // decreases till it exceeds (CUTOFF_CURRENT_MA + BATTERY_THRESHOLD)= 290 mAs
    case STATE_CV_CHARGING:
      DL_GPIO_setPins(GPIO_Battery_Discharging_PORT, GPIO_Battery_Discharging_PIN_PB7_PIN);
      if (batt_current >= batt_cutoff_current + BATTERY_THRESHOLD) {
        // Detect steep voltage drop:
        if (last_voltage != 0 && (last_voltage - batt_voltage) > 100) {
          printf("!!! CV CHARGING: Voltage dropped too fast: %d -> %d mV.\n", last_voltage, batt_voltage);
          charging_state= STATE_ERROR;
          break;
        }
        controller_SetCurrent(TARGET_MCU_ADDRESS, slot_id, charge_current);
      }else {
        charging_state = STATE_FINAL_DISCHARGE;
        dac_initialized= false;
      }
      last_voltage = batt_voltage;
      break;
  
    case STATE_DISCHARGING:
      DL_GPIO_setPins(GPIO_Battery_Charging_PORT, GPIO_Battery_Charging_PIN_PB6_PIN);
      DL_GPIO_setPins(GPIO_Battery_Discharging_PORT, GPIO_Battery_Discharging_PIN_PB7_PIN);
      controller_SetCurrent(TARGET_MCU_ADDRESS, slot_id, charge_current);
      printf("DISCHARGING: Slot %d at %d mA.\n", slot_id, batt_current);

      //Safety Check
      if(batt_voltage< batt_min_voltage){
        charging_state= STATE_ERROR;
        printf("ERROR: Battery voltage below minimum voltage during discharge\n");
      }
      break;
  
    case STATE_FINAL_DISCHARGE:
      //Once the cycle gets done, the battery state transitions to "STATE_MEASUREMENT_DONE"
      battery_data[slot_id].battery_state= STATE_MEASUREMENT_DONE;
      DL_GPIO_clearPins(GPIO_Battery_Charging_PORT, GPIO_Battery_Charging_PIN_PB6_PIN);
      DL_GPIO_clearPins(GPIO_Battery_Discharging_PORT, GPIO_Battery_Discharging_PIN_PB7_PIN);
      controller_SetCurrent(TARGET_MCU_ADDRESS, slot_id, 0);
      charging_state = STATE_IDLE;
      break;
  
    case STATE_ERROR:
      DL_GPIO_clearPins(GPIO_Battery_Charging_PORT, GPIO_Battery_Charging_PIN_PB6_PIN);
      DL_GPIO_clearPins(GPIO_Battery_Discharging_PORT, GPIO_Battery_Discharging_PIN_PB7_PIN);
      printf("ERROR: Slot %d.\n", slot_id);
      break;
  
    case STATE_IDLE:
      DL_GPIO_clearPins(GPIO_Battery_Charging_PORT, GPIO_Battery_Charging_PIN_PB6_PIN);
      DL_GPIO_clearPins(GPIO_Battery_Discharging_PORT, GPIO_Battery_Discharging_PIN_PB7_PIN);
      charging_state = STATE_PRE_CHARGE;
      break;

    default:
      break;
    }
  }
// End of the file