diff --git a/Core/Inc/PSE_unit.h b/Core/Inc/PSE_unit.h
index 5e192b2..0d3d13e 100644
--- a/Core/Inc/PSE_unit.h
+++ b/Core/Inc/PSE_unit.h
@@ -43,5 +43,6 @@ typedef struct{
 } pse_unit;
 
 void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs, uint8_t unit_num);
+void save_units(pse_unit* units, uint8_t unit_num);
 
 #endif 
diff --git a/Core/Inc/PSE_unit_edit_screen.h b/Core/Inc/PSE_unit_edit_screen.h
index 93cc602..14027d7 100644
--- a/Core/Inc/PSE_unit_edit_screen.h
+++ b/Core/Inc/PSE_unit_edit_screen.h
@@ -10,6 +10,6 @@
 
 #include "PSE_unit.h"
 
-void PSE_unit_edit_screen_Gen(lv_obj_t* parent, pse_unit* unit);
+void PSE_unit_edit_screen_Gen(lv_obj_t* parent, pse_unit* units, pse_unit* unit, uint8_t units_num);
 
 #endif /* INC_PSE_EDIT_SCREEN_H_ */
diff --git a/Core/Inc/pse_stepper_planer.h b/Core/Inc/pse_stepper_planer.h
index ff022c9..1cf181a 100644
--- a/Core/Inc/pse_stepper_planer.h
+++ b/Core/Inc/pse_stepper_planer.h
@@ -12,7 +12,7 @@
 
 #define PSE_STEPPER_INTERRUPT_RATE 20000 // 64Mhz (Presc 64, count 50) : 20kHz
 #define PSE_STEPPER_SCREW_PITCH 1000 // M6 : 1000µm / rotation
-#define PSE_STEPPER_STEPS_PER_ROTATION 200 // NEMA17 without microstepping 200 steps/rotation
+#define PSE_STEPPER_STEPS_PER_ROTATION 6400 // NEMA17 200 steps/rotation with 32x microstepping
 
 void pse_sp_start_axis(pse_stepper_conf* conf);
 void pse_sp_stop_axis(pse_stepper_conf* conf);
diff --git a/Core/Src/PSE_unit.c b/Core/Src/PSE_unit.c
index e0ff0c5..8fd4c54 100644
--- a/Core/Src/PSE_unit.c
+++ b/Core/Src/PSE_unit.c
@@ -7,21 +7,81 @@
 
 #include "PSE_unit.h"
 
-// TODO: load from SD-card
-void load_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs, uint8_t unit_num){
-  for(int i = 0; i < unit_num; i++){
-    units[i] = (pse_unit){
-      .enabled = i%2,
-      .port = i,
-      .flow = 1500*i,
-      .volume = 0,
-      .set_volume = 0,
-      .syringe = &syringes[i],
-	  .stepper_conf = &stepper_confs[i],
-    };
-    syringes[i] = (pse_syringe){
-    	.name = "Test",
-    	.diameter = 26700,
-    };
-  }
+#include "fatfs.h"
+#include "lvgl.h"
+
+static void generate_default_units(pse_unit* units, pse_syringe* syringes, pse_stepper_conf* stepper_confs, uint8_t unit_num){
+	for(int i = 0; i < unit_num; i++){
+		units[i] = (pse_unit){
+	      .enabled = i%2,
+	      .port = i,
+	      .flow = 1500*i,
+	      .volume = 0,
+	      .set_volume = 0,
+	      .syringe = &syringes[i],
+		  .stepper_conf = &stepper_confs[i],
+	    };
+	    syringes[i] = (pse_syringe){
+	    	.name = "Test",
+	    	.diameter = 26700,
+	    };
+	  }
+}
+
+
+// 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, uint8_t unit_num){
+	// Open save file
+	FIL saveFile;
+	if(f_open(&saveFile, "PSE_save.txt", FA_READ) != FR_OK){
+		lv_obj_t * mbox1 = lv_msgbox_create(NULL, "Error", "Could not load configuration to SD card", NULL, true);
+		lv_obj_center(mbox1);
+		generate_default_units(units, syringes, stepper_confs, unit_num);
+		return;
+	}
+
+	// read configuration sequentially
+	for(int i = 0; i < unit_num; i++){
+		FRESULT res;
+		UINT bytesRead;
+		res = f_read(&saveFile, &units[i], sizeof(units[i]), &bytesRead);
+		units[i].syringe = &syringes[i];
+		units[i].stepper_conf = &stepper_confs[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);
+
+		if(res != FR_OK){
+			generate_default_units(units, syringes, stepper_confs, unit_num);
+			return;
+		}
+	}
+
+	f_close(&saveFile);
+}
+
+void save_units(pse_unit* units, uint8_t unit_num){
+	// Open save file
+	FIL saveFile;
+	if(f_open(&saveFile, "PSE_save.txt", FA_WRITE | FA_OPEN_ALWAYS) != FR_OK){
+		lv_obj_t * mbox1 = lv_msgbox_create(NULL, "Error", "Could not save configuration to SD card", NULL, true);
+		lv_obj_center(mbox1);
+		return;
+	}
+
+	for(int i = 0; i < unit_num; i++){
+		FRESULT res;
+		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);
+
+		if(res != FR_OK){
+			return;
+		}
+	}
+
+	f_close(&saveFile);
 }
diff --git a/Core/Src/PSE_unit_edit_screen.c b/Core/Src/PSE_unit_edit_screen.c
index b5131ce..4d87a27 100644
--- a/Core/Src/PSE_unit_edit_screen.c
+++ b/Core/Src/PSE_unit_edit_screen.c
@@ -19,13 +19,16 @@
 
 static lv_obj_t* parent_screen;
 static lv_obj_t* this_screen;
+static pse_unit* c_pse_units;
 static pse_unit* c_pse_unit;
+static uint8_t c_pse_units_num;
 
 static void back_button_handler(lv_event_t * e){
   lv_event_code_t code = lv_event_get_code(e);
 
 	if(code == LV_EVENT_CLICKED) {
-    // Save
+		save_units(c_pse_units, c_pse_units_num);
+
 		// update stepper pwm generation
 		pse_stepper_planer_compute_sps(c_pse_unit);
 
@@ -191,13 +194,15 @@ static lv_obj_t* controls_widget(lv_obj_t* parent, pse_unit* unit){
 	return cont;
 }
 
-void PSE_unit_edit_screen_Gen(lv_obj_t* parent, pse_unit* unit){
+void PSE_unit_edit_screen_Gen(lv_obj_t* parent, pse_unit* units, pse_unit* c_unit, uint8_t units_num){
 	parent_screen = parent;
 	// Create a new screen
 	lv_obj_t* scr = lv_obj_create(NULL);
 	this_screen = scr;
 
-	c_pse_unit = unit;
+	c_pse_units = units;
+	c_pse_unit = c_unit;
+	c_pse_units_num = units_num;
 
 	// create the top menu on the top 20%
 	lv_obj_t* top_menu = lv_obj_create(scr);
@@ -226,16 +231,16 @@ void PSE_unit_edit_screen_Gen(lv_obj_t* parent, pse_unit* unit){
 	lv_obj_set_grid_dsc_array(units_grid, widg_col_dsc, widg_row_dsc);
 
 	// Flow widget
-	lv_obj_t* flow = flow_widget(units_grid, unit);
+	lv_obj_t* flow = flow_widget(units_grid, c_unit);
 	lv_obj_set_grid_cell(flow, LV_GRID_ALIGN_CENTER, 0, 1, LV_GRID_ALIGN_CENTER, 0, 1);
 	// Set volume widget
-	lv_obj_t* vol = volume_widget(units_grid, unit);
+	lv_obj_t* vol = volume_widget(units_grid, c_unit);
 	lv_obj_set_grid_cell(vol, LV_GRID_ALIGN_CENTER, 1, 1, LV_GRID_ALIGN_CENTER, 0, 1);
 	// Syringe widget
-	lv_obj_t* syringe = syringe_widget(units_grid, unit);
+	lv_obj_t* syringe = syringe_widget(units_grid, c_unit);
 	lv_obj_set_grid_cell(syringe, LV_GRID_ALIGN_CENTER, 2, 1, LV_GRID_ALIGN_CENTER, 0, 1);
 	// controls widget
-	lv_obj_t* controls = controls_widget(units_grid, unit);
+	lv_obj_t* controls = controls_widget(units_grid, c_unit);
 	lv_obj_set_grid_cell(controls, LV_GRID_ALIGN_CENTER, 3, 1, LV_GRID_ALIGN_CENTER, 0, 1);
 
 	// fade in the new screen
diff --git a/Core/Src/home_screen.c b/Core/Src/home_screen.c
index 712c710..23dd921 100644
--- a/Core/Src/home_screen.c
+++ b/Core/Src/home_screen.c
@@ -66,7 +66,7 @@ static void unit_widget_clicked_handler(lv_event_t* e){
 
 	if(code == LV_EVENT_CLICKED) {
 		pse_unit* unit = lv_event_get_user_data(e);
-		PSE_unit_edit_screen_Gen(screen, unit);
+		PSE_unit_edit_screen_Gen(screen, units, unit, units_num);
 	}
 }
 
diff --git a/Core/Src/main.c b/Core/Src/main.c
index 61c8a56..778149c 100644
--- a/Core/Src/main.c
+++ b/Core/Src/main.c
@@ -231,7 +231,7 @@ int main(void)
   disp_drv.flush_cb = &my_flush_cb;
   lv_disp_drv_register(&disp_drv);
 
-  lv_disp_t * disp = lv_disp_drv_register(&disp_drv);
+  lv_disp_drv_register(&disp_drv);
 
   // load the default theme
   lv_theme_t * th = lv_theme_default_init(lv_disp_get_default(), lv_color_hex(0x2BAEE1), lv_color_hex(0x001361), true, LV_FONT_DEFAULT);
@@ -261,23 +261,19 @@ int main(void)
   // initialize the Touchscreen Driver
   ADS7843_Init(&Touch_Def);
 
-  load_units(pse_units, pse_syringes, pse_stepper_confs, PSE_UNITS_NUM);
-  pse_sp_set_timer(&htim4);
-  Home_Screen_Gen(pse_units, PSE_UNITS_NUM);
-
-  // SD tests
-  char mynewdiskPath[4];
+  // mount the SD card
+  char SD_disk_path[4];
   FATFS FatFs;
-  uint8_t wtext[] = "Hello world";
-  uint32_t wbytes;
-  FIL MyFile;
+  f_mount(&FatFs, SD_disk_path, 0);
 
-  HAL_Delay(1000);
+  // Load saved units
+  load_units(pse_units, pse_syringes, pse_stepper_confs, PSE_UNITS_NUM);
 
-  f_mount(&FatFs, mynewdiskPath, 0);
-  f_open(&MyFile, "STM32.TXT", FA_CREATE_ALWAYS | FA_WRITE);
-  f_write(&MyFile, wtext, sizeof(wtext), (void *)&wbytes);
-  f_close(&MyFile);
+  // Set timer used for step interrupts
+  pse_sp_set_timer(&htim4);
+
+  // Load the home screen
+  Home_Screen_Gen(pse_units, PSE_UNITS_NUM);
   /* USER CODE END 2 */
 
   /* Infinite loop */