set->boottobrew = 1;

            }

            else if(!HAL_GPIO_ReadPin(SW_DOWN)) {

                set->boottobrew = 0;

            }

            // Event Handler

            // N/A

        } break;

        case STATE_SETUNITS:

        {

            // Write text to OLED

            // [ therm :: set windup ]

            // [ g = 12         ]

            ssd1306_DrawString("Units: ", 0, 40);

            ssd1306_drawlogo();

            if(set->temp_units == TEMP_UNITS_FAHRENHEIT)

                ssd1306_DrawString("Fahrenheit", 1, 60);

            else

                ssd1306_DrawString("Celsius   ", 1, 60);

            ssd1306_DrawString("Press to accept", 3, 40);

            // Button handler

            if(SW_BTN_PRESSED) {

                status->state = STATE_SETTEMPOFFSET;

            }

            else if(!HAL_GPIO_ReadPin(SW_UP)) {

                set->temp_units = TEMP_UNITS_FAHRENHEIT;

            }

            else if(!HAL_GPIO_ReadPin(SW_DOWN)) {

                set->temp_units = TEMP_UNITS_CELSIUS;

            }

            // Event Handler

            // N/A

        } break;

        case STATE_SETTEMPOFFSET:

        {

            // Write text to OLED

            // [ therm :: set temp offset ]

            // [ g = 12         ]

            ssd1306_drawlogo();

            char tempstr[6];

            itoa(set->temp_offset, tempstr, 10);

            ssd1306_DrawString("O=", 1, 45);

            ssd1306_DrawString("    ", 1, 57);

            ssd1306_DrawString(tempstr, 1, 57);

            ssd1306_DrawString("Press to accept", 3, 40);

            // Button handler

            if(SW_BTN_PRESSED) {

                save_settings(&set);

                status->state = STATE_IDLE;

            }

            else {

                user_input_signed(&set->temp_offset);

            }

            // Event Handler

            // N/A

        } break;

        case STATE_PREHEAT_BREW:

        {

            // Write text to OLED

            // [ therm : preheating brew ]

            // [ 30 => 120 C             ]

            ssd1306_DrawString("Preheating...", 0, 0);

            //ssd1306_drawlogo();

            draw_setpoint(status);

            status->pid_enabled = 1;

	    status->setpoint = set->setpoint_brew;

            // Button handler

            if(SW_BTN_PRESSED) {

		save_setpoints(&set); // TODO: Check for mod

                status->state = STATE_IDLE;

            }

            else {

                user_input(&set->setpoint_brew);

            }

            // Event Handler

            if(status->temp >= status->setpoint) {

        int8_t signint;

        if(sign) {

            signint = -1;

        }

        else {

            signint = 1;

        }

        // Convert to Fahrenheit

        if(set.temp_units == TEMP_UNITS_FAHRENHEIT)

        {

            status.temp = signint * ((temp_pre*100) + status.temp_frac);

            status.temp = status.temp * 1.8;

            status.temp += 3200;

            status.temp_frac = status.temp % 100;

            status.temp /= 100;

            status.temp += set.temp_offset;

        }

        // Use Celsius values

        else

        {

            status.temp = temp_pre * signint;

            status.temp += set.temp_offset;

        }

    }

}

// PID implementation

// TODO: Make struct that has the last_temp and i_state in it, pass by ref. Make struct that has other input values maybe.

int16_t last_pid_temp = 0;

uint8_t last_pid_temp_frac = 0;

int32_t i_state = 0;

int16_t update_pid(uint16_t k_p, uint16_t k_i, uint16_t k_d, int16_t temp, uint8_t temp_frac, int16_t setpoint) 

{

  // Calculate instantaneous error

  int16_t error = setpoint - temp; // TODO: Use fixed point fraction

  // Proportional component

  int32_t p_term = k_p * error;

  // Error accumulator (integrator)

  i_state += error;

  //  error, we use a "windup guard" 

  // (this happens when the machine is first turned on and

  // it cant help be cold despite its best efforts)

  // not necessary, but this makes windup guard values 

  // relative to the current iGain

  int32_t windup_guard_res = set.windup_guard / k_i;  

  // Calculate integral term with windup guard 

  if (i_state > windup_guard_res) 

    i_state = windup_guard_res;

  else if (i_state < -windup_guard_res) 

    i_state = -windup_guard_res;

  int32_t i_term = k_i * i_state;

  // Calculate differential term (slope since last iteration)

  int32_t d_term = (k_d * (status.temp - last_pid_temp));

  // Save temperature for next iteration

  last_pid_temp = status.temp;

  last_pid_temp_frac = status.temp_frac;

  int16_t result = p_term + i_term - d_term;

  // Put out tenths of percent, 0-1000. 

  if(result > 1000)

    result = 1000;

  else if(result < -1000)

    result = -1000;

  // Return feedback

  return result;

}

uint32_t last_ssr_on = 0;

uint32_t last_vcp_tx = 0;

uint32_t last_led = 0;

int16_t ssr_output = 0; // Duty cycle of ssr, 0 to SSR_PERIOD 

// Turn SSR output on/off according to set duty cycle.

// TODO: Eventually maybe replace with a very slow timer or something. Double-check this code...

void process()

{

    update_temp(); // Read MAX31855

    uint32_t ticks = HAL_GetTick();

#include "stm32f0xx_hal.h"

#include "states.h"

void save_settings(therm_settings_t *tosave)

{

    // TODO: Rework with FLASH read/write 

/*

   Minimal_EEPROM_Unlock();

    // Try programming a word at an address divisible by 4

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_BOOTTOBREW, boottobrew);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_WINDUP_GUARD, windup_guard);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_K_P, k_p);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_K_I, k_i);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_K_D, k_d);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_UNITS, temp_units);

    Minimal_EEPROM_Lock();

*/

}

void save_setpoints(therm_settings_t *tosave)

{

    // TODO: Rework with FLASH read/write 

/*

    Minimal_EEPROM_Unlock();

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_BREWTEMP, setpoint_brew);

    Minimal_EEPROM_ProgramWord(EEPROM_BASE_ADDR + EEPROM_ADDR_STEAMTEMP, setpoint_steam); 

    Minimal_EEPROM_Lock();

*/

}

// TODO: Make a struct that has all settings in it. Pass by ref to this func in a library.

void restore_settings(therm_settings_t *tosave)

{

    // TODO: Rework with FLASH read/write 

/*    Minimal_EEPROM_Unlock();

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    boottobrew = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_BOOTTOBREW));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    windup_guard = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_WINDUP_GUARD));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    k_p = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_K_P));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    k_i = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_K_I));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    k_d = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_K_D));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    setpoint_brew = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_BREWTEMP));

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    setpoint_steam = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_STEAMTEMP));    

    while(Minimal_FLASH_GetStatus()==FLASH_BUSY);

    temp_units = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_UNITS));    

    Minimal_EEPROM_Lock(); */

}