@@ -127,368 +127,399 @@ void update_temp() {
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);
uint32_t ticks = 0;
uint32_t last_ssr_on = 0;
uint32_t last_led = 0;
int32_t setpoint = 0;
uint16_t k_p = 1;
uint16_t k_i = 1;
uint16_t k_d = 1;
uint8_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)
if(ticks - last_led > 400)
GPIO_ToggleBits(LED_POWER);
last_led = ticks;
// Every 200ms, set the SSR on unless output is 0
if((ticks - last_ssr_on > SSR_PERIOD) && ssr_output > 0)
GPIO_SetBits(LED_STAT);
last_ssr_on = ticks;
// Kill SSR after elapsed period less than SSR_PERIOD
if(ticks - last_ssr_on > ssr_output)
GPIO_ResetBits(LED_STAT);
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
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 machine()
uint8_t last_state = state;
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);
switch(state)
// Idle state
case STATE_IDLE:
// Write text to OLED
// [ therm :: idle ]
ssd1306_DrawString("therm :: idle ", 0, 40);
char tempstr[6];
ssd1306_DrawString("Temp: ", 3, 40);
ssd1306_DrawString(" ", 3, 70);
ssd1306_DrawString(tempstr, 3, 72);
ssd1306_drawlogo();
switch(goto_mode) {
case 2:
ssd1306_DrawString("-> brew ", 1, 40);
} break;
case 1:
ssd1306_DrawString("-> set P/I/D", 1, 40);
case 0:
ssd1306_DrawString("-> setup ", 1, 40);
// Button handler
if(!GPIO_ReadInputDataBit(SW_BTN)) {
if(SW_BTN_PRESSED) {
state = STATE_PREHEAT_BREW;
break;
state = STATE_SETP;
default:
else if(!GPIO_ReadInputDataBit(SW_UP) && goto_mode < 2) {
else if(SW_UP_PRESSED && goto_mode < 2) {
goto_mode++;
else if(!GPIO_ReadInputDataBit(SW_DOWN) && k_p > 0 && goto_mode > 0) {
else if(SW_DOWN_PRESSED && k_p > 0 && goto_mode > 0) {
goto_mode--;
// Event Handler
// N/A
case STATE_SETP:
// [ therm :: set p ]
// [ p = 12 ]
ssd1306_DrawString("Proportional", 0, 40);
itoa(k_p, tempstr);
ssd1306_DrawString("P=", 1, 45);
ssd1306_DrawString(" ", 1, 57);
ssd1306_DrawString(tempstr, 1, 57);
ssd1306_DrawString("Press to accept", 3, 40);
state = STATE_SETI;
else if(!GPIO_ReadInputDataBit(SW_UP)) {
k_p++;
else if(!GPIO_ReadInputDataBit(SW_DOWN) && k_p > 0) {
k_p--;
case STATE_SETI:
// [ therm :: set i ]
// [ i = 12 ]
ssd1306_DrawString("Integral", 0, 40);
itoa(k_i, tempstr);
ssd1306_DrawString("I=", 1, 45);
state = STATE_SETD;
k_i++;
else if(!GPIO_ReadInputDataBit(SW_DOWN) && k_i > 0) {
k_i--;
case STATE_SETD:
// [ therm :: set d ]
// [ d = 12 ]
ssd1306_DrawString("Derivative", 0, 40);
itoa(k_d, tempstr);
ssd1306_DrawString("D=", 1, 45);
state = STATE_IDLE;
k_d++;
else if(!GPIO_ReadInputDataBit(SW_DOWN) && k_d > 0) {
k_d--;
case STATE_PREHEAT_BREW:
// [ therm : preheating brew ]
// [ 30 => 120 C ]
ssd1306_DrawString("Preheating...", 0, 40);
draw_setpoint();
setpoint++;
else if(!GPIO_ReadInputDataBit(SW_DOWN) && setpoint > 0) {
setpoint--;
if(temp >= setpoint) {
state = STATE_MAINTAIN_BREW;
case STATE_MAINTAIN_BREW:
// [ therm : ready to brew ]
ssd1306_DrawString("Ready to Brew!", 0, 40);
case STATE_PREHEAT_STEAM:
// [ therm : preheating steam ]
state = STATE_MAINTAIN_STEAM;
case STATE_MAINTAIN_STEAM:
// [ therm : ready to steam ]
ssd1306_DrawString("Ready to Steam!", 0, 40);
// Something is terribly wrong
if(last_state != state) {
// Clear screen on state change
ssd1306_clearscreen();
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;
// Delay a number of systicks
void delay(__IO uint32_t nTime)
TimingDelay = nTime;
while(TimingDelay != 0);
// ISR-triggered decrement of delay and increment of tickcounter
void TimingDelay_Decrement(void)
if (TimingDelay != 0x00)
TimingDelay--;
ticks++;
void init_spi(void)
SPI_InitTypeDef SPI_InitStructure;
Status change: