diff --git a/pid.c b/pid.c
--- a/pid.c
+++ b/pid.c
@@ -1,22 +1,24 @@
-#include "stm32f0xx_hal.h"
-#include "states.h"
+#include "pid.h"
 
 // PID implementation
-// TODO: Make struct that has the last_temp and i_state in it, pass by ref. Make struct that has other input values maybe.
-static int16_t last_pid_temp = 0;
-static uint8_t last_pid_temp_frac = 0;
-static int32_t i_state = 0;
 
-int16_t pid_update(uint16_t k_p, uint16_t k_i, uint16_t k_d, int16_t temp, uint8_t temp_frac, int16_t setpoint, therm_settings_t* set, therm_status_t* status) 
+void pid_init(pid_state_t* state)
+{
+	state->i_state = 0;
+	state->last_pid_temp = 0;
+	state->last_pid_temp_frac = 0;
+}
+
+int16_t pid_update(therm_settings_t* set, therm_status_t* status, pid_state_t *state)
 {
   // Calculate instantaneous error
-  int16_t error = setpoint - temp; // TODO: Use fixed point fraction
+  int16_t error = status->setpoint - status->temp; // TODO: Use fixed point fraction
 
   // Proportional component
-  int32_t p_term = k_p * error;
+  int32_t p_term = set->val.k_p * error;
 
   // Error accumulator (integrator)
-  i_state += error;
+  state->i_state += error;
 
   // to prevent the iTerm getting huge from lots of 
   //  error, we use a "windup guard" 
@@ -24,22 +26,22 @@ int16_t pid_update(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
-  int32_t windup_guard_res = set->val.windup_guard / k_i;  
+  int32_t windup_guard_res = set->val.windup_guard / set->val.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;
+  if (state->i_state > windup_guard_res)
+	  state->i_state = windup_guard_res;
+  else if (state->i_state < -windup_guard_res)
+	  state->i_state = -windup_guard_res;
 
-  int32_t i_term = k_i * i_state;
+  int32_t i_term = set->val.k_i * state->i_state;
 
   // Calculate differential term (slope since last iteration)
-  int32_t d_term = (k_d * (status->temp - last_pid_temp));
+  int32_t d_term = (set->val.k_d * (status->temp - state->last_pid_temp));
 
   // Save temperature for next iteration
-  last_pid_temp = status->temp;
-  last_pid_temp_frac = status->temp_frac;
+  state->last_pid_temp = status->temp;
+  state->last_pid_temp_frac = status->temp_frac;
 
   int16_t result = p_term + i_term - d_term;