// Go backwards and write out remaining digits 

    do{ 

        *--p = digit[i%10];

        i = i/10;

    }while(i);

    return b;

}

static __IO uint32_t TimingDelay;

// Move to header file

void init_gpio();

void init_spi();

void process();

void machine();

int main(void)

{

    // Init clocks

    SystemInit();

    init_gpio();

    // Init USB

    //Set_USBClock();

    //USB_Interrupts_Config();

    //USB_Init();

    GPIO_SetBits(LED_POWER);

    RCC_ClocksTypeDef RCC_Clocks;

    // SysTick end of count event each 1ms

    RCC_GetClocksFreq(&RCC_Clocks);

    SysTick_Config(RCC_Clocks.HCLK_Frequency / 1000);

    GPIO_ResetBits(LED_STAT);

    Delay(100);

    GPIO_SetBits(LED_POWER);

    Delay(500);

    GPIO_ResetBits(LED_POWER);

    init_spi();

    ssd1306_Init();

    ssd1306_block_write();

    ssd1306_DrawString("therm 0.1", 0, 40);

    uint8_t toggle = 0;

    int16_t temp = -231;

    while(1)

    {

        //ssd1306_block_write();

        // Process sensor inputs [TODO: 5hz?]

        process();

        // Run state machine [TODO: 50hz?]

        machine(); 

        // probably just passed the actual port

        // TODO: Grab buttonpresses with interrupts

        //uint8_t sw_btn = GPIO_ReadInputDataBit(SW_BTN);

        //uint8_t sw_up = GPIO_ReadInputDataBit(SW_UP);

        //uint8_t sw_down = GPIO_ReadInputDataBit(SW_DOWN);

        //uint8_t sw_left = GPIO_ReadInputDataBit(SW_LEFT);

        //uint8_t sw_right = GPIO_ReadInputDataBit(SW_RIGHT);

        GPIO_SetBits(LED_POWER);

        Delay(50);

        GPIO_ResetBits(LED_POWER);

        Delay(50);

    }

}

// Read temperature and update global temp vars

int16_t temp = 0;

uint8_t temp_frac = 0;

void update_temp() {

    // Assert CS

    GPIO_ResetBits(MAX_CS);

    Delay(1);

    // This may not clock at all... might need to send 16 bits first

    SPI_I2S_SendData(SPI2, 0xAAAA); // send dummy data

    //SPI_I2S_SendData(SPI2, 0xAA); // send dummy data

    uint16_t temp_pre = SPI_I2S_ReceiveData(SPI2);

    if(temp_pre & 0b0000000000000010) {

    }

    else if(temp_pre & 0b0000000000000001) {

    }

    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 

    if(sign) {

        temp = -temp_pre;

    }

    else {

        temp = temp_pre;

    }

    // Deassert CS

    Delay(1);

    GPIO_SetBits(MAX_CS);

}

int32_t setpoint = 0;

uint16_t k_p = 1;

uint16_t k_i = 1;

uint16_t k_d = 1;

// Process things

void process()

{

    update_temp(); // Read MAX31855

    // TODO: Add calibration offset (linear)

    // Perform PID calculations

    //if(

    GPIO_SetBits(LED_STAT);

    // Write output to SSR

}

enum state {

    STATE_IDLE = 0,

    STATE_SETP,

    STATE_SETI,

    STATE_SETD,

    STATE_PREHEAT_BREW,

    STATE_MAINTAIN_BREW,

    STATE_PREHEAT_STEAM,

    STATE_MAINTAIN_STEAM,

};

void draw_setpoint() {

    char tempstr[3];

    itoa_fp(temp, temp_frac, tempstr);

    //ssd1306_DrawString("        ", 3, 40);

    ssd1306_DrawString(tempstr, 3, 40);

    ssd1306_DrawString("-> ", 3, 80);

    itoa(setpoint, tempstr);

    ssd1306_DrawString("    ", 3, 95);

    ssd1306_DrawString(tempstr, 3, 95);

}

uint8_t state = STATE_IDLE;

uint8_t goto_mode = 2;

// State machine

void machine()

{

    uint8_t last_state = state;

    switch(state)

    {

        // Idle state

        case STATE_IDLE:

        {

            // Write text to OLED

            // [ therm :: idle ]

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

            char tempstr[6];

            itoa_fp(temp, temp_frac, tempstr);

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

            ssd1306_DrawString("    ", 3, 70);

            ssd1306_DrawString(tempstr, 3, 72);

            ssd1306_drawlogo();