diff --git a/Core/Inc/PSE_unit.h b/Core/Inc/PSE_unit.h
index 07213f6..1454db3 100644
--- a/Core/Inc/PSE_unit.h
+++ b/Core/Inc/PSE_unit.h
@@ -31,7 +31,9 @@ typedef struct{
   int32_t steps_counter;
 	uint8_t stop_at_limit; // boolean to stop at stop_steps
 	int32_t stop_steps; // position to stop at
+} pse_stepper_status;
 
+typedef struct{
   GPIO_TypeDef* EN_GPIO_Port; // Pin definitions
   uint16_t EN_GPIO_Pin;
   GPIO_TypeDef* DIR_GPIO_Port;
@@ -59,12 +61,13 @@ typedef struct{
   pse_syringe* syringe; // associated syringe
   pse_stepper_conf* stepper_conf; // hardware configuration for the associated stepper
   pse_home_display* home_display; // Widgets for updating the home screen
+	pse_stepper_status* stepper_status; // stepper position/speed status
 	int32_t start_pos; // movement start position for volume calculation
 	uint32_t nL_per_step; // pL delivered per step
 } pse_unit;
 
 
-void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs, pse_home_display* home_displays, uint8_t unit_num, uint16_t ws_ind);
+void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs, pse_stepper_status* stepper_status, pse_home_display* home_displays, uint8_t unit_num, uint16_t ws_ind);
 void load_units_short(pse_unit* units, uint8_t unit_num, uint16_t ws_ind);
 void save_units(pse_unit* units, uint8_t unit_num, uint16_t ws_ind);
 
diff --git a/Core/Inc/pse_stepper_planer.h b/Core/Inc/pse_stepper_planer.h
index a4d3fe1..60162bc 100644
--- a/Core/Inc/pse_stepper_planer.h
+++ b/Core/Inc/pse_stepper_planer.h
@@ -16,12 +16,12 @@
 #define PSE_STEPPER_JOG_PRESC 64 // jog step frequency 50kHz
 #define PSE_STEPPER_JOG_PERIOD 25 // 64Mhz / 64 / 10 / 2
 
-void pse_sp_start_axis(pse_stepper_conf* conf);
+void pse_sp_start_axis(pse_stepper_conf* conf, pse_stepper_status* status);
 void pse_sp_stop_axis(pse_stepper_conf* conf);
 void pse_sp_set_dir(pse_stepper_conf* conf, int dir);
 int pse_sp_get_dir(pse_stepper_conf* conf);
 void pse_stepper_planer_tick(pse_unit* unit);
-void pse_sp_jog_speed(pse_stepper_conf* conf, int status);
+void pse_sp_jog_speed(pse_stepper_conf* conf, pse_stepper_status* sta, int status);
 
 void pse_sp_set_dir_all(pse_unit* units, int unit_num, int dir);
 void pse_sp_start_all(pse_unit* units, int unit_num);
diff --git a/Core/Src/PSE_unit.c b/Core/Src/PSE_unit.c
index 20006eb..b264a88 100644
--- a/Core/Src/PSE_unit.c
+++ b/Core/Src/PSE_unit.c
@@ -16,7 +16,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-static void generate_default_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs, pse_home_display* home_displays, uint8_t unit_num){
+static void generate_default_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs,pse_stepper_status* stepper_status, pse_home_display* home_displays, uint8_t unit_num){
 	for(int i = 0; i < unit_num; i++){
 		units[i] = (pse_unit){
 	      .enabled = i%2,
@@ -25,8 +25,9 @@ static void generate_default_units(pse_unit* units, pse_syringe* syringes, pse_s
 	      .volume = 0,
 	      .set_volume = 0,
 	      .syringe = &syringes[i],
-		  .stepper_conf = &stepper_confs[i],
-		  .home_display = &home_displays[i],
+			  .stepper_conf = &stepper_confs[i],
+				.stepper_status = &stepper_status[i],
+			  .home_display = &home_displays[i],
 	    };
 	    syringes[i] = (pse_syringe){
 	    	.name = "Test",
@@ -39,7 +40,7 @@ static void generate_default_units(pse_unit* units, pse_syringe* syringes, pse_s
 // Load units from file
 // Units configuration are saved as binary, in the order [pse_unit, pse_syringe, pse_stepper_conf] with each unit back to back
 // In case of any error fallback to a default configuration
-void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs, pse_home_display* home_displays, uint8_t unit_num, uint16_t ws_ind){
+void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs, pse_stepper_status* stepper_status, pse_home_display* home_displays, uint8_t unit_num, uint16_t ws_ind){
 	// Open save file
 	FIL saveFile;
 
@@ -54,7 +55,7 @@ void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* steppe
 	if(f_open(&saveFile, filename, FA_READ) != FR_OK){
 		lv_obj_t * mbox1 = lv_msgbox_create(NULL, "Error", "Could not load configuration from SD card", NULL, true);
 		lv_obj_center(mbox1);
-		generate_default_units(units, syringes, stepper_confs, home_displays, unit_num);
+		generate_default_units(units, syringes, stepper_confs, stepper_status, home_displays, unit_num);
 		free(filename);
 		return;
 	}
@@ -68,12 +69,13 @@ void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* steppe
 		units[i].syringe = &syringes[i];
 		units[i].stepper_conf = &stepper_confs[i];
 		units[i].home_display = &home_displays[i];
+		units[i].stepper_status = &stepper_status[i];
 
 		res += f_read(&saveFile, units[i].syringe, sizeof(pse_syringe), &bytesRead);
-		res += f_read(&saveFile, units[i].stepper_conf, sizeof(pse_stepper_conf), &bytesRead);
+		res += f_read(&saveFile, units[i].stepper_status, sizeof(pse_stepper_status), &bytesRead);
 
 		if(res != FR_OK){
-			generate_default_units(units, syringes, stepper_confs, home_displays, unit_num);
+			generate_default_units(units, syringes, stepper_confs, stepper_status, home_displays, unit_num);
 			return;
 		}
 	}
@@ -82,7 +84,7 @@ void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* steppe
 }
 
 void load_units_short(pse_unit* units, uint8_t unit_num, uint16_t ws_ind){
-	load_units(units, units->syringe, units->stepper_conf, units->home_display, unit_num, ws_ind);
+	load_units(units, units->syringe, units->stepper_conf, units->stepper_status , units->home_display, unit_num, ws_ind);
 }
 
 void save_units(pse_unit* units, uint8_t unit_num, uint16_t ws_ind){
@@ -112,7 +114,7 @@ void save_units(pse_unit* units, uint8_t unit_num, uint16_t ws_ind){
 		UINT bytesRead;
 		res = f_write(&saveFile, &units[i], sizeof(units[i]), &bytesRead);
 		res += f_write(&saveFile, units[i].syringe, sizeof(pse_syringe), &bytesRead);
-		res += f_write(&saveFile, units[i].stepper_conf, sizeof(pse_stepper_conf), &bytesRead);
+		res += f_write(&saveFile, units[i].stepper_status, sizeof(pse_stepper_status), &bytesRead);
 
 		if(res != FR_OK){
 			return;
@@ -124,7 +126,7 @@ void save_units(pse_unit* units, uint8_t unit_num, uint16_t ws_ind){
 }
 
 void pse_unit_compute_volume_delivered(pse_unit* unit){
-	unit->volume = (int64_t)1 * (unit->stepper_conf->steps_counter - unit->start_pos) * unit->nL_per_step / 1000;
+	unit->volume = (int64_t)1 * (unit->stepper_status->steps_counter - unit->start_pos) * unit->nL_per_step / 1000;
 }
 
 void pse_unit_compute_volume_per_step(pse_unit* unit){
diff --git a/Core/Src/PSE_unit_edit_screen.c b/Core/Src/PSE_unit_edit_screen.c
index 2511aaa..19b05e0 100644
--- a/Core/Src/PSE_unit_edit_screen.c
+++ b/Core/Src/PSE_unit_edit_screen.c
@@ -38,10 +38,12 @@ static void back_button_handler(lv_event_t * e){
 
 		// set limit if volume defined
 		if(c_pse_unit->set_volume != 0){
-			c_pse_unit->stepper_conf->stop_at_limit = 1;
-			c_pse_unit->stepper_conf->stop_steps = (uint64_t)1000 * c_pse_unit->set_volume / c_pse_unit->nL_per_step;	}
+			if(c_pse_unit->nL_per_step == 0) return; // TODO: alert popup / better resolution
+			if(c_pse_unit->flow == 0) return;
+			c_pse_unit->stepper_status->stop_at_limit = 1;
+			c_pse_unit->stepper_status->stop_steps = (uint64_t)1000 * c_pse_unit->set_volume / c_pse_unit->nL_per_step;	}
 		else
-			c_pse_unit->stepper_conf->stop_at_limit = 0;
+			c_pse_unit->stepper_status->stop_at_limit = 0;
 
 		// go back to the main menu
 		Home_Screen_Gen(c_pse_units, c_pse_units_num, true);
@@ -167,12 +169,12 @@ static void jog_forward_button_handler(lv_event_t* e){
 	pse_unit* unit = lv_event_get_user_data(e);
 
 	if(code == LV_EVENT_PRESSED) {
-		pse_sp_jog_speed(unit->stepper_conf, 1);
+		pse_sp_jog_speed(unit->stepper_conf, unit->stepper_status, 1);
 		pse_sp_set_dir(unit->stepper_conf, 1);
-		pse_sp_start_axis(unit->stepper_conf);
+		pse_sp_start_axis(unit->stepper_conf, unit->stepper_status);
 	}
 	else if(code == LV_EVENT_RELEASED){
-		pse_sp_jog_speed(unit->stepper_conf, 0);
+		pse_sp_jog_speed(unit->stepper_conf, unit->stepper_status, 0);
 		pse_sp_stop_axis(unit->stepper_conf);
 	}
 }
@@ -182,12 +184,12 @@ static void jog_backward_button_handler(lv_event_t* e){
 	pse_unit* unit = lv_event_get_user_data(e);
 
 	if(code == LV_EVENT_PRESSED) {
-		pse_sp_jog_speed(unit->stepper_conf, 1);
+		pse_sp_jog_speed(unit->stepper_conf, unit->stepper_status, 1);
 		pse_sp_set_dir(unit->stepper_conf, 0);
-		pse_sp_start_axis(unit->stepper_conf);
+		pse_sp_start_axis(unit->stepper_conf, unit->stepper_status);
 	}
 	else if(code == LV_EVENT_RELEASED){
-		pse_sp_jog_speed(unit->stepper_conf, 0);
+		pse_sp_jog_speed(unit->stepper_conf, unit->stepper_status, 0);
 		pse_sp_stop_axis(unit->stepper_conf);
 	}
 }
@@ -197,7 +199,7 @@ static void set_home_button_handler(lv_event_t* e){
 	pse_unit* unit = lv_event_get_user_data(e);
 
 	if(code == LV_EVENT_CLICKED) {
-		unit->stepper_conf->steps_counter = 0;
+		unit->stepper_status->steps_counter = 0;
 	}
 }
 
diff --git a/Core/Src/home_screen.c b/Core/Src/home_screen.c
index 4f80bdb..51caf24 100644
--- a/Core/Src/home_screen.c
+++ b/Core/Src/home_screen.c
@@ -95,12 +95,13 @@ static void unit_home_handler(lv_event_t * e){
 	if(code == LV_EVENT_CLICKED) {
 		pse_unit* unit = lv_event_get_user_data(e);
 		pse_stepper_conf* c = unit->stepper_conf;
-		if(c->steps_counter == 0) return;
-		c->stop_at_limit = 1;
-		c->stop_steps = 0;
-		pse_sp_jog_speed(c, 1);
-		pse_sp_set_dir(c, c->steps_counter < 0);
-		pse_sp_start_axis(c);
+		pse_stepper_status* s = unit->stepper_status;
+		if(s->steps_counter == 0) return;
+		s->stop_at_limit = 1;
+		s->stop_steps = 0;
+		pse_sp_jog_speed(c, s, 1);
+		pse_sp_set_dir(c, s->steps_counter < 0);
+		pse_sp_start_axis(c, s);
 	}
 }
 
diff --git a/Core/Src/pse_stepper_planer.c b/Core/Src/pse_stepper_planer.c
index 1e45fe7..c178876 100644
--- a/Core/Src/pse_stepper_planer.c
+++ b/Core/Src/pse_stepper_planer.c
@@ -15,17 +15,18 @@
 
 void pse_stepper_planer_tick(pse_unit* unit){
 	pse_stepper_conf* c = unit->stepper_conf;
+	pse_stepper_status* s = unit->stepper_status;
 
 	HAL_GPIO_TogglePin(c->STEP_GPIO_Port, c->STEP_GPIO_Pin);
-	c->steps_counter += (pse_sp_get_dir(c)?1:-1) * HAL_GPIO_ReadPin(c->STEP_GPIO_Port, c->STEP_GPIO_Pin);
-	if(c->stop_at_limit && c->steps_counter == c->stop_steps){
-		pse_sp_jog_speed(c, 0);
+	s->steps_counter += (pse_sp_get_dir(c)?1:-1) * HAL_GPIO_ReadPin(c->STEP_GPIO_Port, c->STEP_GPIO_Pin);
+	if(s->stop_at_limit && s->steps_counter == s->stop_steps){
+		pse_sp_jog_speed(c, s, 0);
 		pse_sp_stop_axis(c);
 	}
 }
 
-void pse_sp_start_axis(pse_stepper_conf* conf){
-	if(conf->stop_at_limit && conf->steps_counter == conf->stop_steps) return;
+void pse_sp_start_axis(pse_stepper_conf* conf, pse_stepper_status* status){
+	if(status->stop_at_limit && status->steps_counter == status->stop_steps) return;
 	
 	HAL_GPIO_WritePin(conf->EN_GPIO_Port, conf->EN_GPIO_Pin, GPIO_PIN_RESET);
 	HAL_TIM_Base_Start_IT(conf->tim);
@@ -61,6 +62,8 @@ static uint16_t int_sqrt(uint32_t s){
 
 void pse_stepper_planer_compute_sps(pse_unit* unit){
 	pse_stepper_conf* c = unit->stepper_conf;
+	pse_stepper_status* s = unit->stepper_status;
+	
 	// magic constants are used to approximate pi and other multiplicatives constant as a rationnal
 	uint64_t numerator = (uint64_t)14323 * unit->syringe->diameter * unit->syringe->diameter * PSE_STEPPER_TIMER_CLOCK * PSE_STEPPER_SCREW_PITCH;
 	uint64_t denominator = (uint64_t)607887 * unit->flow * PSE_STEPPER_STEPS_PER_ROTATION;
@@ -77,17 +80,17 @@ void pse_stepper_planer_compute_sps(pse_unit* unit){
 	}
 
 	if(res < 65536){
-		c->tim_presc = 0;
-		c->tim_period = res - 1;
-		__HAL_TIM_SET_AUTORELOAD(c->tim, c->tim_period);
-		__HAL_TIM_SET_PRESCALER(c->tim, c->tim_presc);
+		s->tim_presc = 0;
+		s->tim_period = res - 1;
+		__HAL_TIM_SET_AUTORELOAD(c->tim, s->tim_period);
+		__HAL_TIM_SET_PRESCALER(c->tim, s->tim_presc);
 	}
 	else{
 		uint16_t sqrt = int_sqrt(res);
-		c->tim_presc = sqrt - 1;
-		c->tim_period = sqrt;
-		__HAL_TIM_SET_AUTORELOAD(c->tim, c->tim_period);
-		__HAL_TIM_SET_PRESCALER(c->tim, c->tim_presc);
+		s->tim_presc = sqrt - 1;
+		s->tim_period = sqrt;
+		__HAL_TIM_SET_AUTORELOAD(c->tim, s->tim_period);
+		__HAL_TIM_SET_PRESCALER(c->tim, s->tim_presc);
 	}
 }
 
@@ -100,7 +103,7 @@ void pse_sp_set_dir_all(pse_unit* units, int units_num, int dir){
 void pse_sp_start_all(pse_unit* units, int units_num){
 	for(int i = 0; i < units_num; i++){
 		if(units[i].enabled){
-			pse_sp_start_axis(units[i].stepper_conf);
+			pse_sp_start_axis(units[i].stepper_conf, units[i].stepper_status);
 		}
 	}
 }
@@ -111,13 +114,13 @@ void pse_sp_stop_all(pse_unit* units, int units_num){
 	}
 }
 
-void pse_sp_jog_speed(pse_stepper_conf* conf, int status){
+void pse_sp_jog_speed(pse_stepper_conf* conf, pse_stepper_status* sta, int status){
 	if(status){
 		__HAL_TIM_SET_AUTORELOAD(conf->tim, PSE_STEPPER_JOG_PERIOD);
 		__HAL_TIM_SET_PRESCALER(conf->tim, PSE_STEPPER_JOG_PRESC);
 	}
 	else{
-		__HAL_TIM_SET_AUTORELOAD(conf->tim, conf->tim_period);
-		__HAL_TIM_SET_PRESCALER(conf->tim, conf->tim_presc);
+		__HAL_TIM_SET_AUTORELOAD(conf->tim, sta->tim_period);
+		__HAL_TIM_SET_PRESCALER(conf->tim, sta->tim_presc);
 	}
 }