diff --git a/Inc/stepper.h b/Inc/stepper.h
index 73cfb16..c65683b 100644
--- a/Inc/stepper.h
+++ b/Inc/stepper.h
@@ -11,12 +11,14 @@ typedef struct {
     uint8_t home_pin;
     uint8_t homed:1;
     uint8_t trigger_step:1;
-    int16_t pos;
-    int16_t speed;
-    int16_t ramp_to_speed;
+    int32_t pos;
+    int32_t speed;
+    int32_t ramp_to_speed;
     uint32_t next_step;
 } stepper_T;
   
+#define STEPPERS_MAX_SPEED 300
+
 void Timer1_Init(void);
 void stepper_gpio_init();
 void do_steps();
diff --git a/Makefile b/Makefile
index 4270395..a487317 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ TARGET = Parafraktor
 # debug build?
 DEBUG = 1
 # optimization
-OPT = -Og
+OPT = -O0
 
 
 #######################################
diff --git a/Src/stepper.c b/Src/stepper.c
index 1198469..637dd4d 100644
--- a/Src/stepper.c
+++ b/Src/stepper.c
@@ -89,10 +89,10 @@ void do_steps(){
                steppers[i].speed--;
 
             /* limit max speed */
-            if(steppers[i].speed >= 100)
-               steppers[i].speed=100;
-            if(steppers[i].speed <= -100)
-               steppers[i].speed=-100;
+            if(steppers[i].speed >= STEPPERS_MAX_SPEED)
+               steppers[i].speed=STEPPERS_MAX_SPEED;
+            if(steppers[i].speed <= -STEPPERS_MAX_SPEED)
+               steppers[i].speed=-STEPPERS_MAX_SPEED;
 
             /* get direction from sign */
             if(steppers[i].speed>0)
@@ -122,16 +122,15 @@ void do_steps(){
                 steppers[i].next_step = timer + 1;
             }
 
-            printf("pos %d\tspeed %d\n", steppers[i].pos, steppers[i].speed);
+            printf("motor[%d]: pos %ld\tspeed %d\n", i, steppers[i].pos, steppers[i].speed);
         }
 
         if(steppers[i].homed){
             static uint16_t old_ramp_to_speed;
             old_ramp_to_speed = steppers[i].ramp_to_speed;
 
-            uint16_t *p = (uint16_t*)&rxBuffer[1];
-
-            steppers[i].ramp_to_speed = __builtin_bswap16(*p) - steppers[i].pos;
+            int32_t swapped_val = rxBuffer[2*i+1]<<8 | (rxBuffer[2*i+2]&0xFF);
+            steppers[i].ramp_to_speed = swapped_val - steppers[i].pos;
 
             if(old_ramp_to_speed == 0 && steppers[i].ramp_to_speed != 0)
                 steppers[i].trigger_step = 1;
diff --git a/compile_flags.txt b/compile_flags.txt
index 92d6f97..9edb108 100644
--- a/compile_flags.txt
+++ b/compile_flags.txt
@@ -12,7 +12,7 @@
 -IDrivers/SystemView/Config
 -IDrivers/SystemView/SEGGER
 -IDrivers/SystemView/SYSVIEW
--Og
+-O0
 -Wall
 -fdata-sections
 -ffunction-sections