RCC_ClkInitTypeDef RCC_ClkInitStruct;

  RCC_PeriphCLKInitTypeDef PeriphClkInit;

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI48;

  RCC_OscInitStruct.HSI48State = RCC_HSI48_ON;

  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;

  HAL_RCC_OscConfig(&RCC_OscInitStruct);

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK;

  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI48;

  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;

  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

  HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1);

  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USB;

  PeriphClkInit.UsbClockSelection = RCC_USBCLKSOURCE_HSI48;

  HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit);

  __SYSCFG_CLK_ENABLE();

}

// Read temperature and update global temp vars

int32_t temp = 0;

uint8_t temp_frac = 0;

uint8_t state_resume = 0;

void update_temp() {

    // Assert CS

    HAL_GPIO_WritePin(MAX_CS, 0);

    uint8_t rxdatah[1] = {0x00};

    uint8_t rxdatal[1] = {0x00};

    HAL_SPI_Receive(&hspi1, rxdatah, 1, 100);

    HAL_SPI_Receive(&hspi1, rxdatal, 1, 100);

    // Release CS

    HAL_GPIO_WritePin(MAX_CS, 1);

    // Assemble data array into one var

    uint16_t temp_pre = rxdatal[0] | (rxdatah[0]<<8);

    if(temp_pre & 0b0000000000000010) {

        ssd1306_clearscreen();

        HAL_Delay(100);

        state = STATE_TC_ERROR;

    }

    else if(temp_pre & 0b0000000000000001 && !ignore_tc_error) {

        state_resume = state;

        state = STATE_TC_ERROR;

        temp = 0;

        temp_frac = 0;

    }

    else 

    {

        if(state == STATE_TC_ERROR)

        {

            state = state_resume;

            ssd1306_clearscreen();

        }

        uint8_t sign = temp >> 15;// top bit is sign

        temp_pre = temp_pre >> 2; // Drop 2 lowest bits

        temp_frac = temp_pre & 0b11; // get fractional part

        temp_frac *= 25; // each bit is .25 a degree, up to fixed point

        temp_pre = temp_pre >> 2; // Drop 2 fractional bits 

        int8_t signint;

        if(sign) {

            signint = -1;

        }

        else {

            signint = 1;

        }

        // Convert to Fahrenheit

        if(temp_units == TEMP_UNITS_FAHRENHEIT)

        {

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

            temp = temp * 1.8;

            temp += 3200;

            temp_frac = temp % 100;

            temp /= 100;

        }

        // Use Celsius values

        else

        {

            temp = temp_pre * signint;

        }

    }

    // Print temp to cdc

    CDC_Transmit_FS("Temp: ", 6);

    char tempstr[6];

    zitoa(temp, tempstr);

    CDC_Transmit_FS(tempstr, sizeof(tempstr));

    CDC_Transmit_FS("\r\n", 2);

    CDC_Transmit_FS("\r\n", 2);

    CDC_Transmit_FS("\r\n", 2);

    CDC_Transmit_FS("\r\n", 2);

    CDC_Transmit_FS("\r\n", 2);

}

// 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;

int16_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 = (int16_t)setpoint - (int16_t)temp; // TODO: Use fixed point fraction

  // Proportional component

  int16_t p_term = k_p * error;

  // Error accumulator (integrator)

  i_state += error;

  // to prevent the iTerm getting huge despite lots of 

  //  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

  int16_t windup_guard_res = 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;

  int16_t i_term = k_i * i_state;

  // Calculate differential term (slope since last iteration)

  int16_t d_term = (k_d * (temp - last_pid_temp));

  // Save temperature for next iteration

  last_pid_temp = temp;

  last_pid_temp_frac = 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)

// Process things

void process()

{

    update_temp(); // Read MAX31855

    // TODO: Add calibration offset (linear)

    uint32_t ticks = HAL_GetTick();

    if(ticks - last_led > 400) 

    {

        HAL_GPIO_TogglePin(LED_POWER);

        last_led = ticks;

    }

    // Every 200ms, set the SSR on unless output is 0

    if((ticks - last_ssr_on > SSR_PERIOD))

    {

        if(pid_enabled) 

        {

            // Get ssr output for next time

            int16_t power_percent = update_pid(k_p, k_i, k_d, temp, temp_frac, setpoint);

            //power-percent is 0-1000

            ssr_output = power_percent; //(((uint32_t)SSR_PERIOD * (uint32_t)10 * (uint32_t)100) * power_percent) / (uint32_t)1000000;

        }

        else 

        {

            ssr_output = 0;

        }

        // Only support heating (ssr_output > 0) right now

        if(ssr_output > 0) {

            char tempstr[6];

            itoa(ssr_output, tempstr, 10);

            ssd1306_DrawString(tempstr, 0, 90);

            HAL_GPIO_WritePin(SSR_PIN, 1);

            last_ssr_on = ticks;

        }

    }

    // Kill SSR after elapsed period less than SSR_PERIOD 

    if(ticks - last_ssr_on > ssr_output || ssr_output == 0)

    {

        HAL_GPIO_WritePin(SSR_PIN, 0);

    }

}

uint8_t goto_mode = 2;

// State machine

uint8_t sw_btn_last = 0;

uint8_t sw_up_last = 0;

uint8_t sw_down_last = 0;

uint8_t sw_left_last = 0;

uint8_t sw_right_last = 0;

#define SW_BTN_PRESSED (sw_btn_last == 0 && sw_btn == 1) // rising edge on buttonpress

#define SW_UP_PRESSED (sw_up_last == 0 && sw_up == 1)

#define SW_DOWN_PRESSED (sw_down_last == 0 && sw_down == 1)

#define SW_LEFT_PRESSED (sw_left_last == 0 && sw_left == 1)

#define SW_RIGHT_PRESSED (sw_right_last == 0 && sw_right == 1)

void save_settings()

{

/*

   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()

{

/*

    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()

{

/*    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(); */

}

int16_t last_temp = 21245;

///////////////////////////////////////////////////////////////////////////////////////

/// freaking multiple setpoint support ///

uint8_t step_duration[10] = {0,0,0,0,0,0,0,0,0,0};

int16_t step_setpoint[10] = {0,0,0,0,0,0,0,0,0,0};

uint8_t final_setpoint = 0;

// Multiple screens to set setpoint and duration on each screen

// press center to go to the next one, and press left or right or something to confirm

// When executing, complete on time AND(?) temperature. Maybe allow switching to OR via settings

////////////////////////////////////////////////////////////////////////////////////////////////

void machine()

{

    uint8_t last_state = state;

    uint8_t temp_changed = temp != last_temp;

    last_temp = temp;

    uint8_t sw_btn = !HAL_GPIO_ReadPin(SW_BTN);

    uint8_t sw_up = !HAL_GPIO_ReadPin(SW_UP);

    uint8_t sw_down = !HAL_GPIO_ReadPin(SW_DOWN);

    uint8_t sw_left = !HAL_GPIO_ReadPin(SW_LEFT);

    uint8_t sw_right = !HAL_GPIO_ReadPin(SW_RIGHT);

    switch(state)

    {

        // Idle state

        case STATE_IDLE:

        {

            // Write text to OLED

            // [ therm :: idle ]

            ssd1306_DrawString("therm :: idle ", 0, 40);

            pid_enabled = 0;

            if(temp_changed) {

                char tempstr[6];

                itoa_fp(temp, temp_frac, tempstr);

                ssd1306_DrawString("Temp: ", 3, 40);

                ssd1306_DrawString("    ", 3, 72);

                ssd1306_DrawString(tempstr, 3, 72);

            }

            ssd1306_drawlogo();

            switch(goto_mode) {

                case 2:

                {

                    ssd1306_DrawString("-> heat     ", 1, 40);

                } break;

                case 1:

                {

                    ssd1306_DrawString("-> setup    ", 1, 40);

                } break;

                case 0:

                {

                    ssd1306_DrawString("-> reset    ", 1, 40);

                } break;

            }

            // 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(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) {

                save_settings();

                state = STATE_IDLE;

            }

            else if(!HAL_GPIO_ReadPin(SW_UP)) {

                temp_units = TEMP_UNITS_FAHRENHEIT;

            }

            else if(!HAL_GPIO_ReadPin(SW_DOWN)) {

                temp_units = TEMP_UNITS_CELSIUS;

            }

            // 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();

            pid_enabled = 1;

	    setpoint = setpoint_brew;

            // Button handler

            if(SW_BTN_PRESSED) {

		save_setpoints(); // TODO: Check for mod

                state = STATE_IDLE;

            }

            else {

                user_input(&setpoint_brew);

            }

            // Event Handler

            if(temp >= setpoint) {

                state = STATE_MAINTAIN_BREW;

            }

        } break;

        case STATE_MAINTAIN_BREW:

        {

            // Write text to OLED

            // [ therm : ready to brew ]

            // [ 30 => 120 C           ]

            ssd1306_DrawString("Preheated!", 0, 0);

            //ssd1306_drawlogo();

            draw_setpoint();

            pid_enabled = 1;

	    setpoint = setpoint_brew;

            // Button handler

            if(SW_BTN_PRESSED) {

		save_setpoints(); // TODO: Check for mod

                state = STATE_IDLE;

            }

            else {

                user_input(&setpoint_brew);

            }

            // Event Handler

            // N/A

        } break;

        case STATE_PREHEAT_STEAM:

        {

            // Write text to OLED

            // [ therm : preheating steam ]

                state = STATE_IDLE;

		save_setpoints(); // TODO: Check for mod

            }

            else {

                user_input(&setpoint_steam);

            }

            // Event Handler

            // N/A

        } break;

        case STATE_TC_ERROR:

        {

            // Write text to OLED

            // [ therm : ready to steam ]

            // [ 30 => 120 C            ]

            ssd1306_DrawString("Error:", 0, 0);

            ssd1306_DrawString("Connect thermocouple", 1, 0);

            ssd1306_DrawString("Press -> to ignore", 3, 0);

            // Button handler

            if(SW_BTN_PRESSED) {

                state = STATE_IDLE;

            }

            else if(SW_RIGHT_PRESSED) {

                ignore_tc_error = 1;

                state = STATE_IDLE;

            }

            // Event Handler

            // Maybe handle if TC is plugged in

            // N/A

        } break;

        // Something is terribly wrong

        default:

        {

            state = STATE_IDLE;

            pid_enabled = 0;

        } break;

    }

    if(last_state != state) {

        // Clear screen on state change

        goto_mode = 2;

        ssd1306_clearscreen();

    }

    // Last buttonpress

    sw_btn_last = sw_btn;

    sw_up_last = sw_up;

    sw_down_last = sw_down;

    sw_left_last = sw_left;

    sw_right_last = sw_right;

}

// vim:softtabstop=4 shiftwidth=4 expandtab