diff --git a/Core/Src/Gui/app_gui.c b/Core/Src/Gui/app_gui.c
index 0d29f05..ba7c188 100644
--- a/Core/Src/Gui/app_gui.c
+++ b/Core/Src/Gui/app_gui.c
@@ -13,6 +13,7 @@
 #include "ufb/framebuffer.h"
 #include "ufb/fb_text.h"
 #include "app_safety.h"
+#include "app_heater.h"
 
 struct State s_app = {};
 
@@ -134,10 +135,10 @@ void switch_screen(screen_t pScreen, bool init) {
 
 /** Draw GUI common to all screens */
 static void draw_common_overlay() {
-    SPRINTF(stmp, "%5.1f°C →%3d°C", s_app.oven_temp, s_app.set_temp);
+    SPRINTF(stmp, "%5.1f°C →%3d°C", app_temp_read_oven(), (int) app_heater_get_target());
     fb_text(3, 3, stmp, FONT_3X5, 1);
 
-    if (s_app.heater_enabled) {
+    if (app_heater_get_state()) {
         fb_frame(0, 0, FBW, 11, 1, 1);
     }
 }
diff --git a/Core/Src/Gui/screen_calibration.c b/Core/Src/Gui/screen_calibration.c
index 71a4be1..a17a17c 100644
--- a/Core/Src/Gui/screen_calibration.c
+++ b/Core/Src/Gui/screen_calibration.c
@@ -30,6 +30,17 @@ enum Phase {
     PH_DONE,
 };
 
+static void stop_heater() {
+    app_heater_set_target(0);
+    app_heater_enable(false);
+}
+
+static void calib_abort() {
+    app_temp_restore_calib();
+    stop_heater();
+    switch_screen(screen_home, true);
+}
+
 static void next_phase() {
     PUTS("Phase++\r\n");
     s_calib.phase++;
@@ -47,11 +58,12 @@ static void hello_menu_cb(int opt) {
             // Continue
             next_phase();
             request_paint();
-            app_heater_manual_override(100);
+            app_heater_set_target(100);
+            app_heater_enable(true);
             break;
 
         case 1:
-            switch_screen(screen_home, true);
+            calib_abort();
             break;
     }
 }
@@ -70,12 +82,11 @@ static void sample1_menu_cb(int opt) {
             next_phase();
             request_paint();
             s_calib.sample1 = app_temp_read_oven_raw();
-            app_heater_manual_override(0);
+            app_heater_enable(false);
             break;
 
         case 1:
-            app_heater_manual_override(-1);
-            switch_screen(screen_home, true);
+            calib_abort();
             break;
     }
 }
@@ -94,12 +105,11 @@ static void sample2_menu_cb(int opt) {
             next_phase();
             request_paint();
             s_calib.sample2 = app_temp_read_oven_raw();
-            app_heater_manual_override(0);
+            app_heater_enable(false);
             break;
 
         case 1:
-            app_heater_manual_override(-1);
-            switch_screen(screen_home, true);
+            calib_abort();
             break;
     }
 }
@@ -107,6 +117,8 @@ static void sample2_menu_cb(int opt) {
 void screen_calibration(GuiEvent event)
 {
     if (event == GUI_EVENT_SCREEN_INIT) {
+        app_temp_backup_calib();
+        app_temp_set_calib_temporary(1, 0);
         memset(&s_calib, 0, sizeof(s_calib));
         // continue to the rest - so the menu can be inited
     }
@@ -121,17 +133,20 @@ void screen_calibration(GuiEvent event)
             screen_menu_offset(event, hello_menu_opts, hello_menu_cb, 30);
             break;
 
-        case PH_SAMPLE1: // Heater is active, waiting for mark
-        case PH_SAMPLE2:
+        case PH_SAMPLE1:
             if (event == GUI_EVENT_PAINT) {
-                fb_text(FBW/2, 16, "Zapiš", TEXT_CENTER, 1);
-                fb_text(FBW/2, 26, "teplotu", TEXT_CENTER, 1);
+                fb_text(FBW/2, 16, "Vyčkej", TEXT_CENTER, 1);
+                fb_text(FBW/2, 26, "ustálení", TEXT_CENTER, 1);
             }
-            if (s_calib.phase == PH_SAMPLE1) {
-                screen_menu_offset(event, sample1_menu_opts, sample1_menu_cb, 30);
-            } else {
-                screen_menu_offset(event, sample2_menu_opts, sample2_menu_cb, 30);
+            screen_menu_offset(event, sample1_menu_opts, sample1_menu_cb, 30);
+            break;
+
+        case PH_SAMPLE2:
+            if (event == GUI_EVENT_PAINT) {
+                fb_text(FBW/2, 16, "Vyčkej", TEXT_CENTER, 1);
+                fb_text(FBW/2, 26, "ustálení", TEXT_CENTER, 1);
             }
+            screen_menu_offset(event, sample2_menu_opts, sample2_menu_cb, 30);
             break;
 
         case PH_TEMP1:
@@ -144,8 +159,7 @@ void screen_calibration(GuiEvent event)
 
             if (push_time() > pdMS_TO_TICKS(500)) {
                 input_sound_effect();
-                app_heater_manual_override_clear();
-                switch_screen(screen_home, true);
+                calib_abort();
                 return;
             }
 
@@ -184,7 +198,9 @@ void screen_calibration(GuiEvent event)
                     request_paint();
 
                     if (s_calib.phase == PH_DONE) {
-                        app_heater_manual_override(-1);
+                        app_heater_set_target(0);
+                        app_heater_enable(false);
+
                         // TODO do the math
                         PRINTF("Sample 1 %f, T1 %d\r\n", s_calib.sample1, s_calib.temp1);
                         PRINTF("Sample 2 %f, T2 %d\r\n", s_calib.sample2, s_calib.temp2);
@@ -195,10 +211,13 @@ void screen_calibration(GuiEvent event)
                         float a = (corrected1 - corrected2) / (s_calib.sample1 - s_calib.sample2);
                         float b = corrected1 - a * s_calib.sample1;
 
-                        app_temp_set_calib(a, b);
-                    } else {
-                        // for the next phase
-                        app_heater_manual_override(100);
+                        app_temp_set_persistent_calib(a, b);
+                    } else if (s_calib.phase == PH_SAMPLE1) {
+                        app_heater_set_target(100);
+                        app_heater_enable(true);
+                    } else if (s_calib.phase == PH_SAMPLE2) {
+                        app_heater_set_target(200);
+                        app_heater_enable(true);
                     }
                     break;
                 }
@@ -211,6 +230,7 @@ void screen_calibration(GuiEvent event)
                 fb_text(FBW/2, 36, "→Hlavní menu", TEXT_CENTER, 1);
             }
             if (event == GUI_EVENT_KNOB_RELEASE) {
+                stop_heater();
                 switch_screen(screen_home, 1);
             }
             break;
diff --git a/Core/Src/app_heater.c b/Core/Src/app_heater.c
index 64b81a3..1e8ed5d 100644
--- a/Core/Src/app_heater.c
+++ b/Core/Src/app_heater.c
@@ -98,6 +98,14 @@ void app_heater_set_target(float target) {
     heaterExitCritical();
 }
 
+bool app_heater_get_state() {
+    return state.pid.ctlMode == PID_AUTOMATIC;
+}
+
+float app_heater_get_target() {
+    return state.pid.Setpoint;
+}
+
 // emergency shutdown, this must not block use RTOS since it can be called from fault handlers or interrupt
 void app_heater_emergency_shutdown() {
     // Stop pwm
diff --git a/Core/Src/app_heater.h b/Core/Src/app_heater.h
index edcc9ba..5b912a1 100644
--- a/Core/Src/app_heater.h
+++ b/Core/Src/app_heater.h
@@ -36,4 +36,9 @@ void app_heater_set_target(float target);
 /// Shutdown the heater; This function does not use mutex and just disables the PWM via register access.
 void app_heater_emergency_shutdown();
 
+
+bool app_heater_get_state();
+
+float app_heater_get_target();
+
 #endif //BLUEPILLTROUBA_APP_HEATER_H
diff --git a/Core/Src/app_temp.c b/Core/Src/app_temp.c
index 1d57aa2..62336ee 100644
--- a/Core/Src/app_temp.c
+++ b/Core/Src/app_temp.c
@@ -30,6 +30,8 @@ static struct App {
   float soc_temp;
   float cal_a;
   float cal_b;
+  float saved_cal_a;
+  float saved_cal_b;
   float oventemp_history[OVENTEMP_HISTORY_DEPTH]; // raw temp
   uint16_t adc_averagebuf[AVERAGEBUF_DEPTH * 4];
   uint8_t averagebuf_ptr;
@@ -158,7 +160,7 @@ static void correct_invalid_calib() {
 }
 
 /// Set and persist calibration constants
-void app_temp_set_calib(float a, float b) {
+void app_temp_set_persistent_calib(float a, float b) {
     s_analog.cal_a = a;
     s_analog.cal_b = b;
     correct_invalid_calib();
@@ -177,6 +179,21 @@ void app_temp_set_calib(float a, float b) {
     }
 }
 
+void app_temp_backup_calib() {
+    s_analog.saved_cal_a = s_analog.cal_a;
+    s_analog.saved_cal_b = s_analog.cal_b;
+}
+
+void app_temp_set_calib_temporary(float a, float b) {
+    s_analog.cal_a = a;
+    s_analog.cal_b = b;
+}
+
+void app_temp_restore_calib() {
+    s_analog.cal_a = s_analog.saved_cal_a;
+    s_analog.cal_b = s_analog.saved_cal_b;
+}
+
 void app_analog_init()
 {
     // read calibration constants
diff --git a/Core/Src/app_temp.h b/Core/Src/app_temp.h
index 85425ee..a11554d 100644
--- a/Core/Src/app_temp.h
+++ b/Core/Src/app_temp.h
@@ -10,7 +10,13 @@ void app_analog_init();
 float val_to_c(float val);
 float c_to_val(float c);
 
-void app_temp_set_calib(float a, float b);
+void app_temp_set_persistent_calib(float a, float b);
+
+void app_temp_backup_calib();
+
+void app_temp_set_calib_temporary(float a, float b);
+
+void app_temp_restore_calib();
 
 /**
  * Update temperature measurement.
diff --git a/Lib/ufb/Src/font_57.inc.c b/Lib/ufb/Src/font_57.inc.c
index 47cde97..b9b43b3 100644
--- a/Lib/ufb/Src/font_57.inc.c
+++ b/Lib/ufb/Src/font_57.inc.c
@@ -106,5 +106,6 @@ static const struct utf_glyph5x PROGMEM font57_extra[] = {
     {.utf={.symbol="í"}, {{0x00, 0x44, 0x7d, 0x41, 0x00}}},
     {.utf={.symbol="ž"}, {{0x44, 0x65, 0x56, 0x4d, 0x44}}},
     {.utf={.symbol="ď"}, {{0x38, 0x44, 0x45, 0x48, 0x7f}}},
+    {.utf={.symbol="á"}, {{0x20, 0x54, 0x54, 0x55, 0x79}}},
     {.utf={.symbol="»"}, {{0x22, 0x14, 0x2a, 0x14, 0x08}}},
 };
diff --git a/Lib/ufb/Src/fontedit_57.c b/Lib/ufb/Src/fontedit_57.c
index 1545880..8262322 100644
--- a/Lib/ufb/Src/fontedit_57.c
+++ b/Lib/ufb/Src/fontedit_57.c
@@ -935,6 +935,14 @@ const char *font_extras[] = {
     "#   #",
     "#   #",
     " ####",
+    // 97 "a"
+    "   xx",
+    "     ",
+    " ### ",
+    "    #",
+    " ####",
+    "#   #",
+    " ####",
     // »
     "     ",
     "x x  ",
@@ -967,6 +975,7 @@ const char *font_extras_utf[] = {
     "í",
     "ž",
     "ď",
+    "á",
     "»",
 };