# HG changeset patch
# User Ethan Zonca <ez@ethanzonca.com>
# Date 2014-09-03 21:04:19
# Node ID 68a022485d9bd204d9b8d19834c528835e0d41e1
# Parent  b3359e4381b15da289093184cd21b2c9ef41c22a

Implement windup guard

diff --git a/main.c b/main.c
--- a/main.c
+++ b/main.c
@@ -146,7 +146,9 @@ void update_temp() {
 int16_t last_pid_temp = 0;
 uint8_t last_pid_temp_frac = 0;
 int16_t i_state = 0;
+
 #define WINDUP_GUARD_GAIN 100
+uint16_t windup_guard = WINDUP_GUARD_GAIN;
 
 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) 
 {
@@ -165,13 +167,13 @@ 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 = WINDUP_GUARD_GAIN / k_i;  
+  int16_t windup_guard_res = 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;
+  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)
@@ -203,7 +205,6 @@ int32_t setpoint = 0;
 uint16_t k_p = 1;
 uint16_t k_i = 1;
 uint16_t k_d = 1;
-uint16_t windup_guard = 1;
 int16_t ssr_output = 0; // Duty cycle of ssr, 0 to SSR_PERIOD 
 uint8_t pid_enabled = 0;