# HG changeset patch
# User Ethan Zonca <ez@ethanzonca.com>
# Date 2015-06-01 17:30:55
# Node ID 7527bab9ca743d88d943a547025b748f0232a6b1
# Parent  2025413db75952513539c472ecefc892d2eaaba4

Tweaks to PID word length, commenting

diff --git a/main.c b/main.c
--- a/main.c
+++ b/main.c
@@ -91,8 +91,9 @@ int main(void)
     // Load settings (if any) from EEPROM
     restore_settings();
 
+    // Go to brew instead of idle if configured thusly
     if(set.boottobrew)
-      status.state = STATE_PREHEAT_BREW; // Go to brew instead of idle if configured thusly
+      status.state = STATE_PREHEAT_BREW; 
 
     // Startup screen 
     ssd1306_DrawString("therm v0.2", 1, 40);
@@ -113,8 +114,7 @@ int main(void)
 
 }
 
-/** System Clock Configuration
-*/
+// Clock configuration
 void SystemClock_Config(void)
 {
 
@@ -142,7 +142,7 @@ void SystemClock_Config(void)
 }
 
 
-
+// Grab temperature reading from MAX31855
 void update_temp() {
 
     // Assert CS
@@ -225,15 +225,15 @@ void update_temp() {
 // 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;
+int32_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
+  int16_t error = setpoint - temp; // TODO: Use fixed point fraction
 
   // Proportional component
-  int16_t p_term = k_p * error;
+  int32_t p_term = k_p * error;
 
   // Error accumulator (integrator)
   i_state += error;
@@ -244,17 +244,18 @@ int16_t update_pid(uint16_t k_p, uint16_
   // 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;  
+  int32_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;
+
+  int32_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));
+  int32_t d_term = (k_d * (status.temp - last_pid_temp));
 
   // Save temperature for next iteration
   last_pid_temp = status.temp;
@@ -278,12 +279,12 @@ 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
+// Turn SSR output on/off according to set duty cycle.
+// TODO: Eventually maybe replace with a very slow timer or something. Double-check this code...
 void process()
 {
     update_temp(); // Read MAX31855
 
-    // TODO: Add calibration offset (linear)
     uint32_t ticks = HAL_GetTick();
 
     if(ticks - last_led > 400) 
@@ -343,6 +344,7 @@ void process()
 
 void save_settings()
 {
+    // TODO: Rework with FLASH read/write 
 /*
    Minimal_EEPROM_Unlock();
     // Try programming a word at an address divisible by 4
@@ -358,6 +360,7 @@ void save_settings()
 
 void save_setpoints()
 {
+    // TODO: Rework with FLASH read/write 
 /*
 
     Minimal_EEPROM_Unlock();
@@ -371,6 +374,7 @@ void save_setpoints()
 // TODO: Make a struct that has all settings in it. Pass by ref to this func in a library.
 void restore_settings()
 {
+    // TODO: Rework with FLASH read/write 
 /*    Minimal_EEPROM_Unlock();
     while(Minimal_FLASH_GetStatus()==FLASH_BUSY);
     boottobrew = (*(__IO uint32_t*)(EEPROM_BASE_ADDR + EEPROM_ADDR_BOOTTOBREW));