therm Changeset - 8a3e6f39733b · protofusion repositories

Changeset - 8a3e6f39733b

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Ethan Zonca - 10 years ago 2014-08-26 22:57:39
ez@ethanzonca.com

Initial PID implementation functional

1 file changed with 75 insertions and 4 deletions:

main.c

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main.c

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@@ @@ -62,133 +62,204 @@ int main(void) @@
     // Turn on power LED
     GPIO_SetBits(LED_POWER);
     // TODO: Awesome pwm of power LED (TIM4_CH4 or TIM11_CH1)
     // TODO: PWM of stat led (TIM3_CH2)
     // 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();
     // Startup screen
     ssd1306_DrawString("therm v0.1", 1, 40);
     ssd1306_DrawString("protofusion.org/therm", 3, 0);
     delay(1500);
     ssd1306_clearscreen();
     GPIO_ResetBits(LED_STAT);
     // Main loop
     while(1)
+    {
         // Process sensor inputs
         process();
         // Run state machine
         machine();
+    }
+}
 // 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) {
         ssd1306_DrawString("Fatal Error", 2, 35);
+    }
     else if(temp_pre & 0b0000000000000001) {
         ssd1306_DrawString("Error: No TC", 2, 40);
         temp = 0;
         temp_frac = 0;
+    }
     else
+    {
         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);
+}
 // PID implementation
 int16_t last_pid_temp = 0;
 uint8_t last_pid_temp_frac = 0;
 int16_t i_state = 0;
 #define WINDUP_GUARD_GAIN 100
 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 = WINDUP_GUARD_GAIN / k_i;
   // Calculate integral term with windup guard
   if (i_state > windup_guard)
     i_state = windup_guard;
   else if (i_state < -windup_guard)
     i_state = -windup_guard;
   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)
     result = -1000;
   // Return feedback
   return result;
+}
 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
+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)
     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)
     if((ticks - last_ssr_on > SSR_PERIOD))
+    {
         // 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;
         // Only support heating (ssr_output > 0) right now
         if(ssr_output > 0) {
             char tempstr[6];
             itoa(ssr_output, tempstr);
             ssd1306_DrawString("#=", 2, 45);
             ssd1306_DrawString("    ", 2, 57);
             ssd1306_DrawString(tempstr, 2, 57);
         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;

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