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

            // Button handler

            if(SW_BTN_PRESSED) {

                status->state = STATE_SETUNITS;

            }

            else if(!HAL_GPIO_ReadPin(SW_UP)) {

                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_DrawString("Thermocouple Offset", 0, 40);

            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();

                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(); // TODO: Check for mod

                status->state = STATE_IDLE;

            }

            else {

                user_input(&set->setpoint_brew);

            }

            // Event Handler

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

                status->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(status);

            status->pid_enabled = 1;

	    status->setpoint = set->setpoint_brew;

            // Button handler

            if(SW_BTN_PRESSED) {

		save_setpoints(); // TODO: Check for mod

                status->state = STATE_IDLE;

            }

            else {

                user_input(&set->setpoint_brew);

            }

            // Event Handler

            // N/A

        } break;

        case STATE_PREHEAT_STEAM:

        {

            // Write text to OLED

            // [ therm : preheating steam ]

            // [ 30 => 120 C           ]

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

            //ssd1306_drawlogo();

            draw_setpoint(status);

            status->pid_enabled = 1;

	    status->setpoint = set->setpoint_steam;

            // Button handler

            if(SW_BTN_PRESSED) {

                status->state = STATE_IDLE;

		save_setpoints(); // TODO: Check for mod

            }

            else {

                user_input(&set->setpoint_steam);

            }

            // Event Handler

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

                status->state = STATE_MAINTAIN_STEAM;

            }

        } break;

        case STATE_MAINTAIN_STEAM:

        {

            // Write text to OLED

            // [ therm : ready to steam ]

            // [ 30 => 120 C            ]

            ssd1306_DrawString("Ready to Steam!", 0, 0);

            //ssd1306_drawlogo();

            draw_setpoint(status);

            status->pid_enabled = 1;

	    status->setpoint = set->setpoint_steam;

            // Button handler

            if(SW_BTN_PRESSED) {

                status->state = STATE_IDLE;

		save_setpoints(); // TODO: Check for mod

            }

            else {

                user_input(&set->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("Press -> to ignore", 3, 0);

            // Button handler

            if(SW_BTN_PRESSED) {

                status->state = STATE_IDLE;

            }

            else if(SW_RIGHT_PRESSED) {

                set->ignore_tc_error = 1;

                status->state = STATE_IDLE;

            }

            // Event Handler

            // Maybe handle if TC is plugged in

            // N/A

        } break;

        // Something is terribly wrong

        default:

        {

            status->state = STATE_IDLE;

            status->pid_enabled = 0;

        } break;

    }

    if(last_state != status->state) {

        // Clear screen on state change

        goto_mode = 2;

        trigger_drawsetpoint = 1;

        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;

}

int32_t temp_last = 43002;

int32_t setpoint_last = 10023;

void draw_setpoint(therm_status_t* status) {

    // FIXME: need to do this when switching modes too

    if(status->temp != temp_last || trigger_drawsetpoint) { 

        char tempstr[3];

        itoa_fp(status->temp, status->temp_frac, tempstr);

        ssd1306_DrawStringBig("      ", 3, 0);

        ssd1306_DrawStringBig(tempstr, 3, 0);

    }

    if(trigger_drawsetpoint) 

        ssd1306_DrawStringBig(">", 3, 74);

    if(status->setpoint != setpoint_last || trigger_drawsetpoint) {

        char tempstr[3];

        itoa(status->setpoint, tempstr, 10);

        ssd1306_DrawStringBig("   ", 3, 90);

        ssd1306_DrawStringBig(tempstr, 3, 90);

    }

    trigger_drawsetpoint = 0;

    setpoint_last = status->setpoint;

    temp_last = status->temp;

}

// vim:softtabstop=4 shiftwidth=4 expandtab 

#include "stm32f0xx_hal.h"

#include "config.h"

#include "states.h"

#include "ssd1306.h"

#include "eeprom_min.h"

#include "gpio.h"

#include "spi.h"

#include "stringhelpers.h"

#include "display.h"

#include "usb_device.h"

#include "usbd_cdc_if.h"

// Prototypes

// Move to header file

void process();

void restore_settings();

void save_settings();

void save_setpoints();

void SystemClock_Config(void);

therm_settings_t set;

therm_status_t status;

// Globalish setting vars

SPI_HandleTypeDef hspi1;

static __IO uint32_t TimingDelay;

void deinit(void)

{

    HAL_DeInit();

}

volatile int i=0;

int main(void)

{

    /* Reset of all peripherals, Initializes the Flash interface and the Systick. */

    HAL_Init();

    /* Configure the system clock */

    SystemClock_Config();

    /* Unset bootloader option bytes (if set) */

    void bootloader_unset(void);

    /* Initialize all configured peripherals */

    init_gpio();

    MX_USB_DEVICE_Init();

    // USB startup delay

    HAL_Delay(1000);

    HAL_GPIO_WritePin(LED_POWER, 1);

    // TODO: Awesome pwm of power LED 

    // Configure 1ms SysTick (change if more temporal resolution needed) 

    //RCC_ClocksTypeDef RCC_Clocks;

    //RCC_GetClocksFreq(&RCC_Clocks);

    //SysTick_Config(RCC_Clocks.HCLK_Frequency / 1000);

    // Init SPI busses

    init_spi();

    // Init OLED over SPI

    ssd1306_Init();

    ssd1306_clearscreen();

    // Default settings 

    set.boottobrew = 0;

    set.temp_units = TEMP_UNITS_CELSIUS;

    set.windup_guard = 1;

    set.k_p = 1;

    set.k_i = 1;

    set.k_d = 1;

    set.ignore_tc_error = 0;

    set.setpoint_brew = 0;

    set.setpoint_steam = 0;

    // Default status

    status.temp = 0;

    status.temp_frac = 0;

    status.state_resume = 0;

    status.state = STATE_IDLE;

    status.setpoint = 0;

    status.pid_enabled = 0;

    // Load settings (if any) from EEPROM

    restore_settings();

    if(set.boottobrew)

      status.state = STATE_PREHEAT_BREW; // Go to brew instead of idle if configured thusly

    // Startup screen 

    ssd1306_DrawString("therm v0.1", 1, 40);

    ssd1306_DrawString("protofusion.org/therm", 3, 0);

    HAL_Delay(1500);

    ssd1306_clearscreen();

    // Main loop

    while(1)

    {

        // Process sensor inputs

        process();

        // Run state machine

        display_process(&set, &status); 

    }

}

/** System Clock Configuration

*/

void SystemClock_Config(void)

{

  RCC_OscInitTypeDef RCC_OscInitStruct;

  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();

}

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();

        status.state = STATE_TC_ERROR;

        status.temp = 0;

        status.temp_frac = 0;

    }

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

        status.state_resume = status.state;

        status.state = STATE_TC_ERROR;

        status.temp = 0;

        status.temp_frac = 0;

    }

    else 

    {

        if(status.state == STATE_TC_ERROR)

        {

            status.state = status.state_resume;

            ssd1306_clearscreen();

        }

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

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

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

        status.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(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;

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 = 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;

  int16_t i_term = k_i * i_state;

  // Calculate differential term (slope since last iteration)

  int16_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 

// 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(status.pid_enabled) 

        {

            // Get ssr output for next time

            int16_t power_percent = update_pid(set.k_p, set.k_i, set.k_d, status.temp, status.temp_frac, status.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);

    }

    if(ticks - last_vcp_tx > VCP_TX_FREQ)

    {

        // Print temp to cdc

        char tempstr[16];

        itoa_fp(status.temp, status.temp_frac, tempstr);

        uint8_t numlen = strlen(tempstr);

        tempstr[numlen] = '\r';

        tempstr[numlen+1] = '\n';

        CDC_Transmit_FS(tempstr, numlen+2);

       // while(CDC_Transmit_FS("\r\n", 2) == USBD_BUSY);

        last_vcp_tx = ticks;

    }

}

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); 

#ifndef STATES_H

#define STATES_H

typedef struct {

    int32_t temp;

    uint8_t temp_frac;

    uint8_t state_resume;

    uint8_t state;

    int32_t setpoint;

    uint8_t pid_enabled;

} therm_status_t;

typedef struct {

    uint8_t boottobrew;

    uint8_t temp_units;

    uint16_t windup_guard;

    uint16_t k_p;

    uint16_t k_i;

    uint16_t k_d;

    int16_t temp_offset;

    uint8_t ignore_tc_error;

    int16_t setpoint_brew;

    int16_t setpoint_steam;

} therm_settings_t;

enum tempunits {

    TEMP_UNITS_CELSIUS = 0,

    TEMP_UNITS_FAHRENHEIT,

};

enum state {

    STATE_IDLE = 0,

    STATE_SETP,

    STATE_SETI,

    STATE_SETD,

    STATE_SETSTEPS,

    STATE_SETWINDUP,

    STATE_SETBOOTTOBREW,

    STATE_SETUNITS,

    STATE_SETTEMPOFFSET,

    STATE_PREHEAT_BREW,

    STATE_MAINTAIN_BREW,

    STATE_PREHEAT_STEAM,

    STATE_MAINTAIN_STEAM,

    STATE_TC_ERROR

};

#endif