diff --git a/CMakeLists.txt b/CMakeLists.txt
index 991ed63..4a87bbe 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,7 @@ set(PICO_PSRAM_CS_PIN 47 CACHE STRING "GPIO used as Chip Select for PSRAM")
 set(PICO_PSRAM_SIZE_BYTES 8388608 CACHE STRING "PSRAM size in bytes")
 pico_sdk_init()
 
-add_executable(program main.c st7789.c graphics.c graphics_fb.c utf8.c ds1302.c beep.c ss49e.c)
+add_executable(program main.c st7789.c gui.c graphics.c graphics_fb.c utf8.c ds1302.c beep.c ss49e.c)
 target_link_libraries(program pico_stdlib pico_bootrom pico_rand hardware_adc hardware_dma hardware_gpio hardware_pwm hardware_spi hardware_regs hardware_psram pico_stdio_usb pico_time pico_sync)
 #target_compile_definitions(program PRIVATE PICO_PSRAM_CS_PIN=${PICO_PSRAM_CS_PIN} PICO_PSRAM_SIZE_BYTES=${PICO_PSRAM_CS_PIN})
 target_compile_definitions(program PRIVATE PICO_PSRAM_CS_PIN=0 PICO_PSRAM_SIZE_BYTES=8388608)
diff --git a/graphics.h b/graphics.h
index bbe082d..fc0b472 100644
--- a/graphics.h
+++ b/graphics.h
@@ -4,7 +4,7 @@
 
 #define LCD_OFFSET_X 2
 #define LCD_OFFSET_Y 34
-#define LCD_WIDTH 320
+#define LCD_WIDTH 318
 #define LCD_HEIGHT 172
 #define LETTER_SPACING 2
 
diff --git a/gui.c b/gui.c
new file mode 100644
index 0000000..35c2b76
--- /dev/null
+++ b/gui.c
@@ -0,0 +1,199 @@
+#include "gui.h"
+
+#include <pico/bootrom.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "ds1302.h"
+#include "graphics.h"
+#include "st7789.h"
+#include "units.h"
+
+extern uint16_t ticksPerWindow;
+extern uint totalWheelTicks;
+extern uint wheelTicksFromPowerOn;
+extern DateTime currentDatetime;
+
+extern void reset();
+
+static struct GUIState guiState;
+
+void gui_init() {
+  guiState.screen = 0;
+  guiState.screenState.mainScreen.displayMode = DISPLAY_MODE_DISTANCE_FROM_POWER_ON;
+  guiState.screenState.mainScreen.displayModeChanged = true;
+  guiState.drawnTimeTextWidth = 0;
+  guiState.drawnTimeHours = 24;
+  guiState.drawnTimeMinutes = 60;
+}
+
+void on_button_input(short button, enum ButtonInputType type, uint heldButtons) {
+#ifdef LOGGING
+  printf("button %i %s press\n", button, type == BUTTON_SHORT_PRESS ? "short" : "long");
+#endif
+
+  // handle simultaneous long presses
+  if (button == 2 && (heldButtons & (1 << 3)) || button == 3 && (heldButtons & (1 << 2))) {
+    reset();
+  }
+  if (button == 0 && (heldButtons & (1 << 3)) || button == 3 && (heldButtons & (1 << 0))) {
+    rom_reset_usb_boot(0, 0);
+  }
+
+  // handle simple short and long presses
+  if (button == 3 && guiState.screen == MAIN_SCREEN) {
+    uint oldDispMode = guiState.screenState.mainScreen.displayMode;
+    if (oldDispMode == DISPLAY_MODE_SPEED)
+      guiState.screenState.mainScreen.displayMode = DISPLAY_MODE_DISTANCE_FROM_POWER_ON;
+    else if (oldDispMode == DISPLAY_MODE_DISTANCE_FROM_POWER_ON)
+      guiState.screenState.mainScreen.displayMode = DISPLAY_MODE_TOTAL_DISTANCE;
+    else
+      guiState.screenState.mainScreen.displayMode = DISPLAY_MODE_SPEED;
+    guiState.screenState.mainScreen.displayModeChanged = true;
+  }
+}
+
+uint16_t color565_lerp(uint16_t a, uint16_t b, uint alphaPercent) {
+  uint alphaComplement = 100 - alphaPercent;
+  uint16_t red = ((b >> 11) * alphaPercent + (a >> 11) * alphaComplement) / 100;
+  uint16_t green = (((b >> 5) & 0x3F) * alphaPercent + ((a >> 5) & 0x3F) * alphaComplement) / 100;
+  uint16_t blue = ((b & 0x1F) * alphaPercent + (a & 0x1F) * alphaComplement) / 100;
+  return blue | (green << 5) | (red << 11);
+}
+
+// speed is in "2.1" decimal fixed-point, in km/h
+void draw_speed(uint value) {
+  enum {
+    DIGITS_START_X = 20,
+    DIGITS_START_Y = 37,
+    DIGIT_WIDTH = 64,
+    DIGIT_SPACING = 8,
+  };
+
+  if (value > 999)
+    value = 999;
+
+  const uint16_t speedToColorX[] = {0, 50, 100, 150, 200, 300};
+  const uint16_t speedToColorY[] = {0x04ff, 0x27fb, 0x6fe4, 0xdfe4, 0xfe84, 0xfd04};
+  const size_t speedToColorPointCount = 6;
+
+  uint16_t color = speedToColorY[speedToColorPointCount - 1];
+  for (int i = 1; i < speedToColorPointCount; ++i) {
+    if (value <= speedToColorX[i]) {
+      color = color565_lerp(speedToColorY[i - 1], speedToColorY[i],
+                            (value - speedToColorX[i - 1]) * 100 / (speedToColorX[i] - speedToColorX[i - 1]));
+      break;
+    }
+  }
+
+  lcd_draw_digit(value / 100, DIGITS_START_X, DIGITS_START_Y, color, 0x528a);
+  lcd_draw_digit((value / 10) % 10, DIGITS_START_X + DIGIT_WIDTH + DIGIT_SPACING, DIGITS_START_Y, color, 0x528a);
+  lcd_draw_decimal_point(DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING, DIGITS_START_Y + 101, color);
+  lcd_draw_digit(value % 10, DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING * 2 + 5, DIGITS_START_Y, color, 0x528a);
+}
+
+// distance is in "2.3" decimal fixed-point, in kilometers
+void draw_short_term_distance(uint value) {
+  enum {
+    DIGITS_START_X = 20,
+    DIGITS_START_Y = 37,
+    SMALL_DIGITS_Y_OFFSET = 28,
+    XSMALL_DIGITS_Y_OFFSET = 60,
+    DIGIT_WIDTH = 64,
+    SMALL_DIGIT_WIDTH = 48,
+    XSMALL_DIGIT_WIDTH = 30,
+    DIGIT_SPACING = 8,
+    SMALL_DIGIT_SPACING = 6,
+    XSMALL_DIGIT_SPACING = 4,
+  };
+
+  if (value > 99999)
+    value = 99999;
+
+  lcd_draw_digit(value / 10000, DIGITS_START_X, DIGITS_START_Y, 0xffff, 0x528a);
+  lcd_draw_digit((value / 1000) % 10, DIGITS_START_X + DIGIT_WIDTH + DIGIT_SPACING, DIGITS_START_Y, 0xffff, 0x528a);
+  lcd_draw_decimal_point(DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING, DIGITS_START_Y + 101, 0xffff);
+  lcd_draw_small_digit((value / 100) % 10, DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING * 2 + 10,
+                       DIGITS_START_Y + SMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
+  lcd_draw_small_digit((value / 10) % 10,
+                       DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING * 2 + SMALL_DIGIT_WIDTH + SMALL_DIGIT_SPACING +
+                           10,
+                       DIGITS_START_Y + SMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
+  lcd_draw_xsmall_digit(value % 10,
+                        DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING * 2 + SMALL_DIGIT_WIDTH * 2 +
+                            SMALL_DIGIT_SPACING * 2 + 10,
+                        DIGITS_START_Y + XSMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
+}
+
+// long term distance is in "4.2" decimal fixed-point, in kilometers
+void draw_long_term_distance(uint value) {
+  enum {
+    DIGITS_START_X = 15,
+    DIGITS_START_Y = 50,
+    SMALL_DIGIT_WIDTH = 48,
+    XSMALL_DIGITS_Y_OFFSET = 32,
+    XSMALL_DIGIT_WIDTH = 30,
+    SMALL_DIGIT_SPACING = 6,
+    XSMALL_DIGIT_SPACING = 4,
+  };
+
+  if (value > 999999)
+    value = 999999;
+
+  lcd_draw_small_digit(value / 100000, DIGITS_START_X, DIGITS_START_Y, 0xffff, 0x528a);
+  lcd_draw_small_digit((value / 10000) % 10, DIGITS_START_X + SMALL_DIGIT_WIDTH + SMALL_DIGIT_SPACING, DIGITS_START_Y,
+                       0xffff, 0x528a);
+  lcd_draw_small_digit((value / 1000) % 10, DIGITS_START_X + SMALL_DIGIT_WIDTH * 2 + SMALL_DIGIT_SPACING * 2,
+                       DIGITS_START_Y, 0xffff, 0x528a);
+  lcd_draw_small_digit((value / 100) % 10, DIGITS_START_X + SMALL_DIGIT_WIDTH * 3 + SMALL_DIGIT_SPACING * 3,
+                       DIGITS_START_Y, 0xffff, 0x528a);
+  lcd_draw_decimal_point(DIGITS_START_X + SMALL_DIGIT_WIDTH * 4 + SMALL_DIGIT_SPACING * 4 - 6, DIGITS_START_Y + 76,
+                         0xffff);
+  lcd_draw_xsmall_digit((value / 10) % 10, DIGITS_START_X + SMALL_DIGIT_WIDTH * 4 + SMALL_DIGIT_SPACING * 4 + 10,
+                        DIGITS_START_Y + XSMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
+  lcd_draw_xsmall_digit(value % 10,
+                        DIGITS_START_X + SMALL_DIGIT_WIDTH * 4 + SMALL_DIGIT_SPACING * 4 + XSMALL_DIGIT_WIDTH +
+                            XSMALL_DIGIT_SPACING + 10,
+                        DIGITS_START_Y + XSMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
+}
+
+void update_lcd() {
+  if (guiState.screen == MAIN_SCREEN) {
+    bool forceRedrawClock = guiState.screenState.mainScreen.displayModeChanged;
+    if (guiState.screenState.mainScreen.displayModeChanged) {
+      // lcd_fill_rectangle(49, 27, 213, 113, 0x0000);
+      st7789_fill(0x0000);
+      guiState.screenState.mainScreen.displayModeChanged = false;
+    }
+
+    if (guiState.screenState.mainScreen.displayMode == DISPLAY_MODE_SPEED) {
+      uint convertedSpeed = ticksPerWindow * cmphPerTpw / 10000;
+      draw_speed(convertedSpeed);
+      lcd_write_string("Скорость", 10, 0, 0xffff, 0x0000);
+      lcd_write_string("км/ч", 241, 126, 0xffff, 0x0000);
+    } else if (guiState.screenState.mainScreen.displayMode == DISPLAY_MODE_DISTANCE_FROM_POWER_ON) {
+      uint convertedDistance = wheelTicksFromPowerOn * cmPerTick / 100;
+      draw_short_term_distance(convertedDistance);
+      lcd_write_string("Текущий путь", 10, 0, 0xffff, 0x0000);
+      lcd_write_string("км", 280, 37, 0xffff, 0x0000);
+    } else if (guiState.screenState.mainScreen.displayMode == DISPLAY_MODE_TOTAL_DISTANCE) {
+      uint convertedDistance = totalWheelTicks * cmPerTick / 1000;
+      draw_long_term_distance(convertedDistance);
+      lcd_write_string("Общий путь", 10, 0, 0xffff, 0x0000);
+      lcd_write_string("км", 280, 37, 0xffff, 0x0000);
+    }
+
+    if (forceRedrawClock || guiState.drawnTimeHours != currentDatetime.hour ||
+        guiState.drawnTimeMinutes != currentDatetime.minute) {
+      lcd_fill_rectangle(305 - guiState.drawnTimeTextWidth, 0, guiState.drawnTimeTextWidth, 24, 0x0000);
+      guiState.drawnTimeHours = currentDatetime.hour;
+      guiState.drawnTimeMinutes = currentDatetime.minute;
+      char timeDisplay[6];
+      memset(timeDisplay, ' ', sizeof(timeDisplay));
+      timeDisplay[5] = 0;
+      sprintf(timeDisplay, "%i:%02i", currentDatetime.hour, currentDatetime.minute);
+      lcd_write_string(timeDisplay, 305 - lcd_string_width(timeDisplay), 0, 0xffff, 0x0000);
+      guiState.drawnTimeTextWidth = lcd_string_width(timeDisplay);
+    }
+  }
+}
diff --git a/gui.h b/gui.h
new file mode 100644
index 0000000..3017cb9
--- /dev/null
+++ b/gui.h
@@ -0,0 +1,91 @@
+#ifndef VELOMETER_GUI_H
+#define VELOMETER_GUI_H
+#include "config.h"
+#include <pico/stdlib.h>
+
+enum ButtonInputType {
+  BUTTON_SHORT_PRESS,
+  BUTTON_LONG_PRESS,
+};
+
+enum GUIScreen {
+  MAIN_SCREEN,
+  MENU_SCREEN,
+};
+
+enum DisplayMode {
+  DISPLAY_MODE_SPEED,
+  DISPLAY_MODE_DISTANCE_FROM_POWER_ON,
+  DISPLAY_MODE_TOTAL_DISTANCE,
+};
+
+enum MenuOptionType {
+  MENU_OPTION_NUMBER,
+  MENU_OPTION_ONOFF,
+  MENU_OPTION_TEXT,
+  MENU_OPTION_LINK,
+};
+
+#define TEXT_EDIT_STATIC_BUFFER_SIZE 18
+struct TextEditState {
+  uint textLength;     // number of characters in input
+  uint textByteLength; // number of bytes occupied by characters
+
+  // fixed-size buffers for most cases
+  char staticTextBuffer[TEXT_EDIT_STATIC_BUFFER_SIZE];
+  uint8_t staticCharWidthBuffer[TEXT_EDIT_STATIC_BUFFER_SIZE];
+
+  // the same thing but in heap for longer input
+  bool heapBufferInUse;
+  char *heapTextBuffer;
+  uint8_t *heapCharWidthBuffer;
+  uint heapTextBufferCapacity;
+  uint heapCharWidthBufferCapacity;
+
+  // visual edit field properties
+  uint cursorPos;           // in characters
+  uint cursorPosCharOffset; // for quicker character addressing inside a UTF-8 string
+  uint scrollOffset;        // in pixels
+};
+
+struct MenuScreenState {
+  enum {
+    MENU_SCREEN_STATE_CHOOSING_OPTION,
+    MENU_SCREEN_STATE_EDITING_OPTION,
+  } subState;
+  union {
+    struct {
+      uint chosenOptionIndex;
+      short scrollAnimationProgress;
+    } choosingOption;
+    struct {
+      uint optionIndex;
+      enum MenuOptionType optionType;
+      union {
+        uint numberValue;
+        bool onOffValue;
+        struct TextEditState textEditState;
+      };
+    } editingOption;
+  };
+};
+
+struct GUIState {
+  uint screen;
+  union {
+    struct {
+      uint displayMode;
+      bool displayModeChanged;
+    } mainScreen;
+    struct MenuScreenState menuScreen;
+  } screenState;
+  uint8_t drawnTimeHours;
+  uint8_t drawnTimeMinutes;
+  uint16_t drawnTimeTextWidth;
+};
+
+void gui_init();
+void on_button_input(short button, enum ButtonInputType type, uint heldButtons);
+void update_lcd();
+
+#endif
diff --git a/main.c b/main.c
index 7e888a7..8bc9cc4 100644
--- a/main.c
+++ b/main.c
@@ -1,3 +1,5 @@
+#include "config.h"
+
 #include <boot/picobin.h>
 #include <hardware/adc.h>
 #include <hardware/dma.h>
@@ -17,46 +19,11 @@
 
 #include "ds1302.h"
 #include "graphics.h"
+#include "gui.h"
 #include "pins.h"
 #include "ss49e.h"
 #include "st7789.h"
-
-#define LOGGING
-
-#define BUTTON_DEBOUNCE_DELAY_us 3000
-#define BUTTON_HOLD_TIME_ms 1000
-#define TICKS_PER_REVOLUTION 6
-#define SPEED_MEASUREMENT_INTERVAL_ms 100
-#define SPEED_MEASUREMENT_WINDOW_SIZE 16
-
-#define SPEED_MEASUREMENT_WINDOW_INTERVAL (SPEED_MEASUREMENT_INTERVAL_ms * SPEED_MEASUREMENT_WINDOW_SIZE)
-
-enum GUIScreen {
-  MAIN_SCREEN,
-  SETTINGS_SCREEN,
-};
-
-enum DisplayMode {
-  DISPLAY_MODE_SPEED,
-  DISPLAY_MODE_DISTANCE_FROM_POWER_ON,
-  DISPLAY_MODE_TOTAL_DISTANCE,
-};
-
-struct GUIState {
-  uint screen;
-  union {
-    struct {
-      uint displayMode;
-      bool displayModeChanged;
-    } mainScreen;
-    struct {
-      //...
-    } settingsScreen;
-  } screenState;
-  uint8_t drawnTimeHours;
-  uint8_t drawnTimeMinutes;
-  uint16_t drawnTimeTextWidth;
-};
+#include "units.h"
 
 void on_gpio_interrupt(uint pin, uint32_t eventMask);
 static void __not_in_flash_func(dma_irq_handler)();
@@ -66,8 +33,6 @@ void on_button_short_press(uint button);
 void on_button_long_press(uint button);
 void on_wheel_hall_sensor_tick();
 
-void update_lcd();
-void gui_init(struct GUIState *state);
 void init_button_states();
 void save_to_rtc();
 bool load_from_rtc();
@@ -79,11 +44,6 @@ const uint16_t BRIGHTNESS_CONVERT_TABLE_X[] = {0, 10, 20, 30, 40, 50, 60, 70, 80
 const uint16_t BRIGHTNESS_CONVERT_TABLE_Y[] = {0, 7, 12, 21, 37, 64, 111, 194, 338, 588, 1024};
 const size_t BRIGHTNESS_CONVERT_LABLE_LEN = 11;
 
-const uint millimetersPerRevolution = 1540;
-const uint cmphPerTpw = 360000 * millimetersPerRevolution / SPEED_MEASUREMENT_WINDOW_INTERVAL /
-                        TICKS_PER_REVOLUTION;                                // cm/hour per Ticks/window
-const uint cmPerTick = millimetersPerRevolution / TICKS_PER_REVOLUTION / 10; // cm per tick
-
 int16_t convert_brightness(int16_t input) {
   for (int i = 0; i < BRIGHTNESS_CONVERT_LABLE_LEN - 1; ++i) {
     if (input < BRIGHTNESS_CONVERT_TABLE_X[i + 1]) {
@@ -99,10 +59,11 @@ int16_t convert_brightness(int16_t input) {
 
 struct PushButtonState {
   alarm_id_t debounceAlarm, holdAlarm;
-  bool currentState, prevState, isHeld;
+  bool currentState, prevState;
 };
 
-struct PushButtonState buttonStates[4];
+static struct PushButtonState buttonStates[4];
+static uint heldButtons;
 
 // for debug (and for the future)
 absolute_time_t lastWheelTickTime = 0;
@@ -127,18 +88,6 @@ DateTime currentDatetime;
 // unused currently
 // repeating_timer_t audioPlaybackTimer;
 
-struct GUIState guiState;
-
-const uint16_t *find_splash_image_offset(const uint16_t *start) {
-  const uint16_t marker[3] = {0x6f66, 0x626f, 0x7261};
-  for (int offs = 0; offs < 2 * 1024 * 1024; ++offs) {
-    if (start[offs + 0] == marker[0] && start[offs + 1] == marker[1] && start[offs + 2] == marker[2]) {
-      return start + offs;
-    }
-  }
-  return NULL;
-}
-
 int main() {
 #ifdef LOGGING
   stdio_usb_init();
@@ -182,7 +131,7 @@ int main() {
   adc_gpio_init(42);
   adc_select_input(2);
   adc_set_round_robin(1 << 2);
-  adc_set_clkdiv(3000 / 1); // 16kHz for 1 sensor
+  adc_set_clkdiv(3000.0f / 1.0f); // 16kHz for 1 sensor
   adc_fifo_setup(true, true, 1, false, false);
 
   // wheel sensor (with N-S alternating magnet arrangement)
@@ -247,7 +196,7 @@ int main() {
   pwm_set_chan_level(3, PWM_CHAN_B, 0);
   pwm_set_enabled(3, true);
 
-  gui_init(&guiState);
+  gui_init();
 
   absolute_time_t nextLcdUpdateTime = delayed_by_ms(get_absolute_time(), 50);
   absolute_time_t nextClockUpdateTime = get_absolute_time();
@@ -370,10 +319,10 @@ int64_t button_debounce_callback(alarm_id_t alarmId, void *userData) {
       buttonState->holdAlarm = add_alarm_in_ms(BUTTON_HOLD_TIME_ms, button_hold_callback, (void *)buttonIndex, false);
     } else {
       buttonState->holdAlarm = -1;
-      if (!buttonState->isHeld)
-        on_button_short_press(buttonIndex);
+      if (!(heldButtons & (1 << buttonIndex)))
+        on_button_input(buttonIndex, BUTTON_SHORT_PRESS, heldButtons);
       else
-        buttonState->isHeld = false;
+        heldButtons &= ~(1 << buttonIndex);
     }
   }
   return 0;
@@ -384,37 +333,11 @@ int64_t button_hold_callback(alarm_id_t alarmId, void *userData) {
   uint buttonIndex = (uint)userData;
   struct PushButtonState *buttonState = &buttonStates[buttonIndex];
   buttonState->holdAlarm = -1;
-  buttonState->isHeld = true;
-  on_button_long_press(buttonIndex);
+  heldButtons |= 1 << buttonIndex;
+  on_button_input(buttonIndex, BUTTON_LONG_PRESS, heldButtons);
   return 0;
 }
 
-void on_button_short_press(uint button) {
-#ifdef LOGGING
-  printf("button %i short press\n", button);
-#endif
-  if (button == 3 && guiState.screen == MAIN_SCREEN) {
-    uint oldDispMode = guiState.screenState.mainScreen.displayMode;
-    if (oldDispMode == DISPLAY_MODE_SPEED)
-      guiState.screenState.mainScreen.displayMode = DISPLAY_MODE_DISTANCE_FROM_POWER_ON;
-    else if (oldDispMode == DISPLAY_MODE_DISTANCE_FROM_POWER_ON)
-      guiState.screenState.mainScreen.displayMode = DISPLAY_MODE_TOTAL_DISTANCE;
-    else
-      guiState.screenState.mainScreen.displayMode = DISPLAY_MODE_SPEED;
-    guiState.screenState.mainScreen.displayModeChanged = true;
-  }
-}
-
-void on_button_long_press(uint button) {
-#ifdef LOGGING
-  printf("button %i long press\n");
-#endif
-  if (button == 2 && buttonStates[3].isHeld ||
-      button == 3 && buttonStates[2].isHeld) { // if buttons 2 & 3 pressed and held simultaneously...
-    reset();
-  }
-}
-
 void on_wheel_hall_sensor_tick() {
   ++intervalWheelTicks[currentInterval];
   ++totalWheelTicks;
@@ -422,178 +345,14 @@ void on_wheel_hall_sensor_tick() {
   printf("\t\t\tTICK\7\n");
 }
 
-uint16_t color565_lerp(uint16_t a, uint16_t b, uint alphaPercent) {
-  uint alphaComplement = 100 - alphaPercent;
-  uint16_t red = ((b >> 11) * alphaPercent + (a >> 11) * alphaComplement) / 100;
-  uint16_t green = (((b >> 5) & 0x3F) * alphaPercent + ((a >> 5) & 0x3F) * alphaComplement) / 100;
-  uint16_t blue = ((b & 0x1F) * alphaPercent + (a & 0x1F) * alphaComplement) / 100;
-  return blue | (green << 5) | (red << 11);
-}
-
-// speed is in "2.1" decimal fixed-point, in km/h
-void draw_speed(uint value) {
-#define DIGITS_START_X 20
-#define DIGITS_START_Y 37
-#define DIGIT_WIDTH 64
-#define DIGIT_SPACING 8
-
-  if (value > 999)
-    value = 999;
-
-  const uint16_t speedToColorX[] = {0, 50, 100, 150, 200, 300};
-  const uint16_t speedToColorY[] = {0x04ff, 0x27fb, 0x6fe4, 0xdfe4, 0xfe84, 0xfd04};
-  const size_t speedToColorPointCount = 6;
-
-  uint16_t color = speedToColorY[speedToColorPointCount - 1];
-  for (int i = 1; i < speedToColorPointCount; ++i) {
-    if (value <= speedToColorX[i]) {
-      color = color565_lerp(speedToColorY[i - 1], speedToColorY[i],
-                            (value - speedToColorX[i - 1]) * 100 / (speedToColorX[i] - speedToColorX[i - 1]));
-      break;
-    }
-  }
-
-  lcd_draw_digit(value / 100, DIGITS_START_X, DIGITS_START_Y, color, 0x528a);
-  lcd_draw_digit((value / 10) % 10, DIGITS_START_X + DIGIT_WIDTH + DIGIT_SPACING, DIGITS_START_Y, color, 0x528a);
-  lcd_draw_decimal_point(DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING, DIGITS_START_Y + 101, color);
-  lcd_draw_digit(value % 10, DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING * 2 + 5, DIGITS_START_Y, color, 0x528a);
-
-#undef DIGITS_START_X
-#undef DIGITS_START_Y
-#undef DIGIT_WIDTH
-#undef DIGIT_SPACING
-}
-
-// distance is in "2.3" decimal fixed-point, in kilometers
-void draw_short_term_distance(uint value) {
-#define DIGITS_START_X 20
-#define DIGITS_START_Y 37
-#define SMALL_DIGITS_Y_OFFSET 28
-#define XSMALL_DIGITS_Y_OFFSET 60
-#define DIGIT_WIDTH 64
-#define SMALL_DIGIT_WIDTH 48
-#define XSMALL_DIGIT_WIDTH 30
-#define DIGIT_SPACING 8
-#define SMALL_DIGIT_SPACING 6
-#define XSMALL_DIGIT_SPACING 4
-
-  if (value > 99999)
-    value = 99999;
-
-  lcd_draw_digit(value / 10000, DIGITS_START_X, DIGITS_START_Y, 0xffff, 0x528a);
-  lcd_draw_digit((value / 1000) % 10, DIGITS_START_X + DIGIT_WIDTH + DIGIT_SPACING, DIGITS_START_Y, 0xffff, 0x528a);
-  lcd_draw_decimal_point(DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING, DIGITS_START_Y + 101, 0xffff);
-  lcd_draw_small_digit((value / 100) % 10, DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING * 2 + 10,
-                       DIGITS_START_Y + SMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
-  lcd_draw_small_digit((value / 10) % 10,
-                       DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING * 2 + SMALL_DIGIT_WIDTH + SMALL_DIGIT_SPACING +
-                           10,
-                       DIGITS_START_Y + SMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
-  lcd_draw_xsmall_digit(value % 10,
-                        DIGITS_START_X + DIGIT_WIDTH * 2 + DIGIT_SPACING * 2 + SMALL_DIGIT_WIDTH * 2 +
-                            SMALL_DIGIT_SPACING * 2 + 10,
-                        DIGITS_START_Y + XSMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
-
-#undef DIGITS_START_X
-#undef DIGITS_START_Y
-#undef DIGIT_WIDTH
-#undef DIGIT_SPACING
-#undef XSMALL_DIGITS_Y_OFFSET
-}
-
-// long term distance is in "4.2" decimal fixed-point, in kilometers
-void draw_long_term_distance(uint value) {
-#define DIGITS_START_X 15
-#define DIGITS_START_Y 50
-#define XSMALL_DIGITS_Y_OFFSET 32
-#define XSMALL_DIGIT_WIDTH 30
-#define XSMALL_DIGIT_SPACING 4
-
-  if (value > 999999)
-    value = 999999;
-
-  lcd_draw_small_digit(value / 100000, DIGITS_START_X, DIGITS_START_Y, 0xffff, 0x528a);
-  lcd_draw_small_digit((value / 10000) % 10, DIGITS_START_X + SMALL_DIGIT_WIDTH + SMALL_DIGIT_SPACING, DIGITS_START_Y,
-                       0xffff, 0x528a);
-  lcd_draw_small_digit((value / 1000) % 10, DIGITS_START_X + SMALL_DIGIT_WIDTH * 2 + SMALL_DIGIT_SPACING * 2,
-                       DIGITS_START_Y, 0xffff, 0x528a);
-  lcd_draw_small_digit((value / 100) % 10, DIGITS_START_X + SMALL_DIGIT_WIDTH * 3 + SMALL_DIGIT_SPACING * 3,
-                       DIGITS_START_Y, 0xffff, 0x528a);
-  lcd_draw_decimal_point(DIGITS_START_X + SMALL_DIGIT_WIDTH * 4 + SMALL_DIGIT_SPACING * 4 - 6, DIGITS_START_Y + 76,
-                         0xffff);
-  lcd_draw_xsmall_digit((value / 10) % 10, DIGITS_START_X + SMALL_DIGIT_WIDTH * 4 + SMALL_DIGIT_SPACING * 4 + 10,
-                        DIGITS_START_Y + XSMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
-  lcd_draw_xsmall_digit(value % 10,
-                        DIGITS_START_X + SMALL_DIGIT_WIDTH * 4 + SMALL_DIGIT_SPACING * 4 + XSMALL_DIGIT_WIDTH +
-                            XSMALL_DIGIT_SPACING + 10,
-                        DIGITS_START_Y + XSMALL_DIGITS_Y_OFFSET, 0xffff, 0x528a);
-
-#undef DIGITS_START_X
-#undef DIGITS_START_Y
-#undef XSMALL_DIGITS_Y_OFFSET
-#undef XSMALL_DIGIT_WIDTH
-#undef XSMALL_DIGIT_SPACING
-}
-
-void update_lcd() {
-  if (guiState.screen == MAIN_SCREEN) {
-    bool forceRedrawClock = guiState.screenState.mainScreen.displayModeChanged;
-    if (guiState.screenState.mainScreen.displayModeChanged) {
-      // lcd_fill_rectangle(49, 27, 213, 113, 0x0000);
-      st7789_fill(0x0000);
-      guiState.screenState.mainScreen.displayModeChanged = false;
-    }
-
-    if (guiState.screenState.mainScreen.displayMode == DISPLAY_MODE_SPEED) {
-      uint convertedSpeed = ticksPerWindow * cmphPerTpw / 10000;
-      draw_speed(convertedSpeed);
-      lcd_write_string("Скорость", 10, 0, 0xffff, 0x0000);
-      lcd_write_string("км/ч", 241, 126, 0xffff, 0x0000);
-    } else if (guiState.screenState.mainScreen.displayMode == DISPLAY_MODE_DISTANCE_FROM_POWER_ON) {
-      uint convertedDistance = wheelTicksFromPowerOn * cmPerTick / 100;
-      draw_short_term_distance(convertedDistance);
-      lcd_write_string("Текущий путь", 10, 0, 0xffff, 0x0000);
-      lcd_write_string("км", 280, 37, 0xffff, 0x0000);
-    } else if (guiState.screenState.mainScreen.displayMode == DISPLAY_MODE_TOTAL_DISTANCE) {
-      uint convertedDistance = totalWheelTicks * cmPerTick / 1000;
-      draw_long_term_distance(convertedDistance);
-      lcd_write_string("Общий путь", 10, 0, 0xffff, 0x0000);
-      lcd_write_string("км", 280, 37, 0xffff, 0x0000);
-    }
-
-    if (forceRedrawClock || guiState.drawnTimeHours != currentDatetime.hour ||
-        guiState.drawnTimeMinutes != currentDatetime.minute) {
-      lcd_fill_rectangle(305 - guiState.drawnTimeTextWidth, 0, guiState.drawnTimeTextWidth, 24, 0x0000);
-      guiState.drawnTimeHours = currentDatetime.hour;
-      guiState.drawnTimeMinutes = currentDatetime.minute;
-      char timeDisplay[6];
-      memset(timeDisplay, ' ', sizeof(timeDisplay));
-      timeDisplay[5] = 0;
-      sprintf(timeDisplay, "%i:%02i", currentDatetime.hour, currentDatetime.minute);
-      lcd_write_string(timeDisplay, 305 - lcd_string_width(timeDisplay), 0, 0xffff, 0x0000);
-      guiState.drawnTimeTextWidth = lcd_string_width(timeDisplay);
-    }
-  } else if (guiState.screen == SETTINGS_SCREEN) {
-  }
-}
-
-void gui_init(struct GUIState *state) {
-  state->screen = 0;
-  state->screenState.mainScreen.displayMode = DISPLAY_MODE_DISTANCE_FROM_POWER_ON;
-  state->screenState.mainScreen.displayModeChanged = true;
-  state->drawnTimeTextWidth = 0;
-  state->drawnTimeHours = 24;
-  state->drawnTimeMinutes = 60;
-}
-
 void init_button_states() {
   for (int i = 0; i < 4; ++i) {
     buttonStates[i].debounceAlarm = -100;
     buttonStates[i].holdAlarm = -1;
     buttonStates[i].currentState = 0;
     buttonStates[i].prevState = 0;
-    buttonStates[i].isHeld = 0;
   }
+  heldButtons = 0;
 }
 
 void reset() {