feat: merge PR #522 - add HalDisplay and HalGPIO abstraction layer

Cherry-picked upstream PR #522 (da4d3b5) with conflict resolution:
- Added new lib/hal/ files (HalDisplay, HalGPIO)
- Updated GfxRenderer to use HalDisplay, preserving base viewable margins
- Adopted PR #522's MappedInputManager lookup table implementation
- Updated main.cpp to use HAL while preserving custom Serial initialization
- Updated all EInkDisplay::RefreshMode references to HalDisplay::RefreshMode

This introduces a Hardware Abstraction Layer for display and GPIO,
enabling easier emulation and testing.

lib/GfxRenderer/GfxRenderer.cpp

@@ -10,19 +10,19 @@ void GfxRenderer::rotateCoordinates(const int x, const int y, int* rotatedX, int
       // Logical portrait (480x800) → panel (800x480)
       // Rotation: 90 degrees clockwise
       *rotatedX = y;
-      *rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - x;
+      *rotatedY = HalDisplay::DISPLAY_HEIGHT - 1 - x;
       break;
     }
     case LandscapeClockwise: {
       // Logical landscape (800x480) rotated 180 degrees (swap top/bottom and left/right)
-      *rotatedX = EInkDisplay::DISPLAY_WIDTH - 1 - x;
+      *rotatedX = HalDisplay::DISPLAY_WIDTH - 1 - x;
-      *rotatedY = EInkDisplay::DISPLAY_HEIGHT - 1 - y;
+      *rotatedY = HalDisplay::DISPLAY_HEIGHT - 1 - y;
       break;
     }
     case PortraitInverted: {
       // Logical portrait (480x800) → panel (800x480)
       // Rotation: 90 degrees counter-clockwise
-      *rotatedX = EInkDisplay::DISPLAY_WIDTH - 1 - y;
+      *rotatedX = HalDisplay::DISPLAY_WIDTH - 1 - y;
       *rotatedY = x;
       break;
     }
@@ -36,7 +36,7 @@ void GfxRenderer::rotateCoordinates(const int x, const int y, int* rotatedX, int
 }
 
 void GfxRenderer::drawPixel(const int x, const int y, const bool state) const {
-  uint8_t* frameBuffer = einkDisplay.getFrameBuffer();
+  uint8_t* frameBuffer = display.getFrameBuffer();
 
   // Early return if no framebuffer is set
   if (!frameBuffer) {
@@ -49,14 +49,13 @@ void GfxRenderer::drawPixel(const int x, const int y, const bool state) const {
   rotateCoordinates(x, y, &rotatedX, &rotatedY);
 
   // Bounds checking against physical panel dimensions
-  if (rotatedX < 0 || rotatedX >= EInkDisplay::DISPLAY_WIDTH || rotatedY < 0 ||
+  if (rotatedX < 0 || rotatedX >= HalDisplay::DISPLAY_WIDTH || rotatedY < 0 || rotatedY >= HalDisplay::DISPLAY_HEIGHT) {
-      rotatedY >= EInkDisplay::DISPLAY_HEIGHT) {
     Serial.printf("[%lu] [GFX] !! Outside range (%d, %d) -> (%d, %d)\n", millis(), x, y, rotatedX, rotatedY);
     return;
   }
 
   // Calculate byte position and bit position
-  const uint16_t byteIndex = rotatedY * EInkDisplay::DISPLAY_WIDTH_BYTES + (rotatedX / 8);
+  const uint16_t byteIndex = rotatedY * HalDisplay::DISPLAY_WIDTH_BYTES + (rotatedX / 8);
   const uint8_t bitPosition = 7 - (rotatedX % 8);  // MSB first
 
   if (state) {
@@ -202,7 +201,7 @@ void GfxRenderer::drawImage(const uint8_t bitmap[], const int x, const int y, co
       break;
   }
   // TODO: Rotate bits
-  einkDisplay.drawImage(bitmap, rotatedX, rotatedY, width, height);
+  display.drawImage(bitmap, rotatedX, rotatedY, width, height);
 }
 
 void GfxRenderer::drawImageRotated(const uint8_t bitmap[], const int x, const int y, const int width, const int height,
@@ -519,22 +518,20 @@ void GfxRenderer::fillPolygon(const int* xPoints, const int* yPoints, int numPoi
   free(nodeX);
 }
 
-void GfxRenderer::clearScreen(const uint8_t color) const { einkDisplay.clearScreen(color); }
+void GfxRenderer::clearScreen(const uint8_t color) const { display.clearScreen(color); }
 
 void GfxRenderer::invertScreen() const {
-  uint8_t* buffer = einkDisplay.getFrameBuffer();
+  uint8_t* buffer = display.getFrameBuffer();
   if (!buffer) {
     Serial.printf("[%lu] [GFX] !! No framebuffer in invertScreen\n", millis());
     return;
   }
-  for (int i = 0; i < EInkDisplay::BUFFER_SIZE; i++) {
+  for (int i = 0; i < HalDisplay::BUFFER_SIZE; i++) {
     buffer[i] = ~buffer[i];
   }
 }
 
-void GfxRenderer::displayBuffer(const EInkDisplay::RefreshMode refreshMode) const {
+void GfxRenderer::displayBuffer(const HalDisplay::RefreshMode refreshMode) const { display.displayBuffer(refreshMode); }
-  einkDisplay.displayBuffer(refreshMode);
-}
 
 std::string GfxRenderer::truncatedText(const int fontId, const char* text, const int maxWidth,
                                        const EpdFontFamily::Style style) const {
@@ -553,13 +550,13 @@ int GfxRenderer::getScreenWidth() const {
     case Portrait:
     case PortraitInverted:
       // 480px wide in portrait logical coordinates
-      return EInkDisplay::DISPLAY_HEIGHT;
+      return HalDisplay::DISPLAY_HEIGHT;
     case LandscapeClockwise:
     case LandscapeCounterClockwise:
       // 800px wide in landscape logical coordinates
-      return EInkDisplay::DISPLAY_WIDTH;
+      return HalDisplay::DISPLAY_WIDTH;
   }
-  return EInkDisplay::DISPLAY_HEIGHT;
+  return HalDisplay::DISPLAY_HEIGHT;
 }
 
 int GfxRenderer::getScreenHeight() const {
@@ -567,13 +564,13 @@ int GfxRenderer::getScreenHeight() const {
     case Portrait:
     case PortraitInverted:
       // 800px tall in portrait logical coordinates
-      return EInkDisplay::DISPLAY_WIDTH;
+      return HalDisplay::DISPLAY_WIDTH;
     case LandscapeClockwise:
     case LandscapeCounterClockwise:
       // 480px tall in landscape logical coordinates
-      return EInkDisplay::DISPLAY_HEIGHT;
+      return HalDisplay::DISPLAY_HEIGHT;
   }
-  return EInkDisplay::DISPLAY_WIDTH;
+  return HalDisplay::DISPLAY_WIDTH;
 }
 
 int GfxRenderer::getSpaceWidth(const int fontId) const {
@@ -902,17 +899,18 @@ void GfxRenderer::drawTextRotated90CCW(const int fontId, const int x, const int
   }
 }
 
-uint8_t* GfxRenderer::getFrameBuffer() const { return einkDisplay.getFrameBuffer(); }
+uint8_t* GfxRenderer::getFrameBuffer() const { return display.getFrameBuffer(); }
 
-size_t GfxRenderer::getBufferSize() { return EInkDisplay::BUFFER_SIZE; }
+size_t GfxRenderer::getBufferSize() { return HalDisplay::BUFFER_SIZE; }
 
-void GfxRenderer::grayscaleRevert() const { einkDisplay.grayscaleRevert(); }
+// unused
+// void GfxRenderer::grayscaleRevert() const { display.grayscaleRevert(); }
 
-void GfxRenderer::copyGrayscaleLsbBuffers() const { einkDisplay.copyGrayscaleLsbBuffers(einkDisplay.getFrameBuffer()); }
+void GfxRenderer::copyGrayscaleLsbBuffers() const { display.copyGrayscaleLsbBuffers(display.getFrameBuffer()); }
 
-void GfxRenderer::copyGrayscaleMsbBuffers() const { einkDisplay.copyGrayscaleMsbBuffers(einkDisplay.getFrameBuffer()); }
+void GfxRenderer::copyGrayscaleMsbBuffers() const { display.copyGrayscaleMsbBuffers(display.getFrameBuffer()); }
 
-void GfxRenderer::displayGrayBuffer() const { einkDisplay.displayGrayBuffer(); }
+void GfxRenderer::displayGrayBuffer() const { display.displayGrayBuffer(); }
 
 void GfxRenderer::freeBwBufferChunks() {
   for (auto& bwBufferChunk : bwBufferChunks) {
@@ -930,7 +928,7 @@ void GfxRenderer::freeBwBufferChunks() {
  * Returns true if buffer was stored successfully, false if allocation failed.
  */
 bool GfxRenderer::storeBwBuffer() {
-  const uint8_t* frameBuffer = einkDisplay.getFrameBuffer();
+  const uint8_t* frameBuffer = display.getFrameBuffer();
   if (!frameBuffer) {
     Serial.printf("[%lu] [GFX] !! No framebuffer in storeBwBuffer\n", millis());
     return false;
@@ -985,14 +983,14 @@ void GfxRenderer::restoreBwBuffer() {
     // CRITICAL: Even if restore fails, we must clean up the grayscale state
     // to prevent grayscaleRevert() from being called with corrupted RAM state
     // Use the current framebuffer content (which may not be ideal but prevents worse issues)
-    uint8_t* frameBuffer = einkDisplay.getFrameBuffer();
+    uint8_t* frameBuffer = display.getFrameBuffer();
     if (frameBuffer) {
-      einkDisplay.cleanupGrayscaleBuffers(frameBuffer);
+      display.cleanupGrayscaleBuffers(frameBuffer);
     }
     return;
   }
 
-  uint8_t* frameBuffer = einkDisplay.getFrameBuffer();
+  uint8_t* frameBuffer = display.getFrameBuffer();
   if (!frameBuffer) {
     Serial.printf("[%lu] [GFX] !! No framebuffer in restoreBwBuffer\n", millis());
     freeBwBufferChunks();
@@ -1005,7 +1003,7 @@ void GfxRenderer::restoreBwBuffer() {
       Serial.printf("[%lu] [GFX] !! BW buffer chunks not stored - this is likely a bug\n", millis());
       freeBwBufferChunks();
       // CRITICAL: Clean up grayscale state even on mid-restore failure
-      einkDisplay.cleanupGrayscaleBuffers(frameBuffer);
+      display.cleanupGrayscaleBuffers(frameBuffer);
       return;
     }
 
@@ -1013,7 +1011,7 @@ void GfxRenderer::restoreBwBuffer() {
     memcpy(frameBuffer + offset, bwBufferChunks[i], BW_BUFFER_CHUNK_SIZE);
   }
 
-  einkDisplay.cleanupGrayscaleBuffers(frameBuffer);
+  display.cleanupGrayscaleBuffers(frameBuffer);
 
   freeBwBufferChunks();
   Serial.printf("[%lu] [GFX] Restored and freed BW buffer chunks\n", millis());
@@ -1024,9 +1022,9 @@ void GfxRenderer::restoreBwBuffer() {
  * Use this when BW buffer was re-rendered instead of stored/restored.
  */
 void GfxRenderer::cleanupGrayscaleWithFrameBuffer() const {
-  uint8_t* frameBuffer = einkDisplay.getFrameBuffer();
+  uint8_t* frameBuffer = display.getFrameBuffer();
   if (frameBuffer) {
-    einkDisplay.cleanupGrayscaleBuffers(frameBuffer);
+    display.cleanupGrayscaleBuffers(frameBuffer);
   }
 }
 

lib/GfxRenderer/GfxRenderer.h

@@ -1,7 +1,7 @@
 #pragma once
 
-#include <EInkDisplay.h>
 #include <EpdFontFamily.h>
+#include <HalDisplay.h>
 
 #include <map>
 
@@ -24,8 +24,8 @@ class GfxRenderer {
 
  private:
   static constexpr size_t BW_BUFFER_CHUNK_SIZE = 8000;  // 8KB chunks to allow for non-contiguous memory
-  static constexpr size_t BW_BUFFER_NUM_CHUNKS = EInkDisplay::BUFFER_SIZE / BW_BUFFER_CHUNK_SIZE;
+  static constexpr size_t BW_BUFFER_NUM_CHUNKS = HalDisplay::BUFFER_SIZE / BW_BUFFER_CHUNK_SIZE;
-  static_assert(BW_BUFFER_CHUNK_SIZE * BW_BUFFER_NUM_CHUNKS == EInkDisplay::BUFFER_SIZE,
+  static_assert(BW_BUFFER_CHUNK_SIZE * BW_BUFFER_NUM_CHUNKS == HalDisplay::BUFFER_SIZE,
                 "BW buffer chunking does not line up with display buffer size");
 
   // Base viewable margins (hardware-specific, before bezel compensation)
@@ -34,7 +34,7 @@ class GfxRenderer {
   static constexpr int BASE_VIEWABLE_MARGIN_BOTTOM = 3;
   static constexpr int BASE_VIEWABLE_MARGIN_LEFT = 3;
 
-  EInkDisplay& einkDisplay;
+  HalDisplay& display;
   RenderMode renderMode;
   Orientation orientation;
   int bezelCompensation = 0;  // Pixels to add for bezel defect compensation
@@ -47,7 +47,7 @@ class GfxRenderer {
   void rotateCoordinates(int x, int y, int* rotatedX, int* rotatedY) const;
 
  public:
-  explicit GfxRenderer(EInkDisplay& einkDisplay) : einkDisplay(einkDisplay), renderMode(BW), orientation(Portrait) {}
+  explicit GfxRenderer(HalDisplay& halDisplay) : display(halDisplay), renderMode(BW), orientation(Portrait) {}
   ~GfxRenderer() { freeBwBufferChunks(); }
 
   // Viewable margins (includes bezel compensation applied to the configured edge)
@@ -79,7 +79,7 @@ class GfxRenderer {
   // Screen ops
   int getScreenWidth() const;
   int getScreenHeight() const;
-  void displayBuffer(EInkDisplay::RefreshMode refreshMode = EInkDisplay::FAST_REFRESH) const;
+  void displayBuffer(HalDisplay::RefreshMode refreshMode = HalDisplay::FAST_REFRESH) const;
   // EXPERIMENTAL: Windowed update - display only a rectangular region
   void displayWindow(int x, int y, int width, int height) const;
   void invertScreen() const;

lib/hal/HalDisplay.cpp

@@ -0,0 +1,51 @@
+#include <HalDisplay.h>
+#include <HalGPIO.h>
+
+#define SD_SPI_MISO 7
+
+HalDisplay::HalDisplay() : einkDisplay(EPD_SCLK, EPD_MOSI, EPD_CS, EPD_DC, EPD_RST, EPD_BUSY) {}
+
+HalDisplay::~HalDisplay() {}
+
+void HalDisplay::begin() { einkDisplay.begin(); }
+
+void HalDisplay::clearScreen(uint8_t color) const { einkDisplay.clearScreen(color); }
+
+void HalDisplay::drawImage(const uint8_t* imageData, uint16_t x, uint16_t y, uint16_t w, uint16_t h,
+                           bool fromProgmem) const {
+  einkDisplay.drawImage(imageData, x, y, w, h, fromProgmem);
+}
+
+EInkDisplay::RefreshMode convertRefreshMode(HalDisplay::RefreshMode mode) {
+  switch (mode) {
+    case HalDisplay::FULL_REFRESH:
+      return EInkDisplay::FULL_REFRESH;
+    case HalDisplay::HALF_REFRESH:
+      return EInkDisplay::HALF_REFRESH;
+    case HalDisplay::FAST_REFRESH:
+    default:
+      return EInkDisplay::FAST_REFRESH;
+  }
+}
+
+void HalDisplay::displayBuffer(HalDisplay::RefreshMode mode) { einkDisplay.displayBuffer(convertRefreshMode(mode)); }
+
+void HalDisplay::refreshDisplay(HalDisplay::RefreshMode mode, bool turnOffScreen) {
+  einkDisplay.refreshDisplay(convertRefreshMode(mode), turnOffScreen);
+}
+
+void HalDisplay::deepSleep() { einkDisplay.deepSleep(); }
+
+uint8_t* HalDisplay::getFrameBuffer() const { return einkDisplay.getFrameBuffer(); }
+
+void HalDisplay::copyGrayscaleBuffers(const uint8_t* lsbBuffer, const uint8_t* msbBuffer) {
+  einkDisplay.copyGrayscaleBuffers(lsbBuffer, msbBuffer);
+}
+
+void HalDisplay::copyGrayscaleLsbBuffers(const uint8_t* lsbBuffer) { einkDisplay.copyGrayscaleLsbBuffers(lsbBuffer); }
+
+void HalDisplay::copyGrayscaleMsbBuffers(const uint8_t* msbBuffer) { einkDisplay.copyGrayscaleMsbBuffers(msbBuffer); }
+
+void HalDisplay::cleanupGrayscaleBuffers(const uint8_t* bwBuffer) { einkDisplay.cleanupGrayscaleBuffers(bwBuffer); }
+
+void HalDisplay::displayGrayBuffer() { einkDisplay.displayGrayBuffer(); }

lib/hal/HalDisplay.h

@@ -0,0 +1,52 @@
+#pragma once
+#include <Arduino.h>
+#include <EInkDisplay.h>
+
+class HalDisplay {
+ public:
+  // Constructor with pin configuration
+  HalDisplay();
+
+  // Destructor
+  ~HalDisplay();
+
+  // Refresh modes
+  enum RefreshMode {
+    FULL_REFRESH,  // Full refresh with complete waveform
+    HALF_REFRESH,  // Half refresh (1720ms) - balanced quality and speed
+    FAST_REFRESH   // Fast refresh using custom LUT
+  };
+
+  // Initialize the display hardware and driver
+  void begin();
+
+  // Display dimensions
+  static constexpr uint16_t DISPLAY_WIDTH = EInkDisplay::DISPLAY_WIDTH;
+  static constexpr uint16_t DISPLAY_HEIGHT = EInkDisplay::DISPLAY_HEIGHT;
+  static constexpr uint16_t DISPLAY_WIDTH_BYTES = DISPLAY_WIDTH / 8;
+  static constexpr uint32_t BUFFER_SIZE = DISPLAY_WIDTH_BYTES * DISPLAY_HEIGHT;
+
+  // Frame buffer operations
+  void clearScreen(uint8_t color = 0xFF) const;
+  void drawImage(const uint8_t* imageData, uint16_t x, uint16_t y, uint16_t w, uint16_t h,
+                 bool fromProgmem = false) const;
+
+  void displayBuffer(RefreshMode mode = RefreshMode::FAST_REFRESH);
+  void refreshDisplay(RefreshMode mode = RefreshMode::FAST_REFRESH, bool turnOffScreen = false);
+
+  // Power management
+  void deepSleep();
+
+  // Access to frame buffer
+  uint8_t* getFrameBuffer() const;
+
+  void copyGrayscaleBuffers(const uint8_t* lsbBuffer, const uint8_t* msbBuffer);
+  void copyGrayscaleLsbBuffers(const uint8_t* lsbBuffer);
+  void copyGrayscaleMsbBuffers(const uint8_t* msbBuffer);
+  void cleanupGrayscaleBuffers(const uint8_t* bwBuffer);
+
+  void displayGrayBuffer();
+
+ private:
+  EInkDisplay einkDisplay;
+};

lib/hal/HalGPIO.cpp

@@ -0,0 +1,55 @@
+#include <HalGPIO.h>
+#include <SPI.h>
+#include <esp_sleep.h>
+
+void HalGPIO::begin() {
+  inputMgr.begin();
+  SPI.begin(EPD_SCLK, SPI_MISO, EPD_MOSI, EPD_CS);
+  pinMode(BAT_GPIO0, INPUT);
+  pinMode(UART0_RXD, INPUT);
+}
+
+void HalGPIO::update() { inputMgr.update(); }
+
+bool HalGPIO::isPressed(uint8_t buttonIndex) const { return inputMgr.isPressed(buttonIndex); }
+
+bool HalGPIO::wasPressed(uint8_t buttonIndex) const { return inputMgr.wasPressed(buttonIndex); }
+
+bool HalGPIO::wasAnyPressed() const { return inputMgr.wasAnyPressed(); }
+
+bool HalGPIO::wasReleased(uint8_t buttonIndex) const { return inputMgr.wasReleased(buttonIndex); }
+
+bool HalGPIO::wasAnyReleased() const { return inputMgr.wasAnyReleased(); }
+
+unsigned long HalGPIO::getHeldTime() const { return inputMgr.getHeldTime(); }
+
+void HalGPIO::startDeepSleep() {
+  esp_deep_sleep_enable_gpio_wakeup(1ULL << InputManager::POWER_BUTTON_PIN, ESP_GPIO_WAKEUP_GPIO_LOW);
+  // Ensure that the power button has been released to avoid immediately turning back on if you're holding it
+  while (inputMgr.isPressed(BTN_POWER)) {
+    delay(50);
+    inputMgr.update();
+  }
+  // Enter Deep Sleep
+  esp_deep_sleep_start();
+}
+
+int HalGPIO::getBatteryPercentage() const {
+  static const BatteryMonitor battery = BatteryMonitor(BAT_GPIO0);
+  return battery.readPercentage();
+}
+
+bool HalGPIO::isUsbConnected() const {
+  // U0RXD/GPIO20 reads HIGH when USB is connected
+  return digitalRead(UART0_RXD) == HIGH;
+}
+
+bool HalGPIO::isWakeupByPowerButton() const {
+  const auto wakeupCause = esp_sleep_get_wakeup_cause();
+  const auto resetReason = esp_reset_reason();
+  if (isUsbConnected()) {
+    return wakeupCause == ESP_SLEEP_WAKEUP_GPIO;
+  } else {
+    return (wakeupCause == ESP_SLEEP_WAKEUP_UNDEFINED) && (resetReason == ESP_RST_POWERON);
+  }
+}

lib/hal/HalGPIO.h

@@ -0,0 +1,61 @@
+#pragma once
+
+#include <Arduino.h>
+#include <BatteryMonitor.h>
+#include <InputManager.h>
+
+// Display SPI pins (custom pins for XteinkX4, not hardware SPI defaults)
+#define EPD_SCLK 8   // SPI Clock
+#define EPD_MOSI 10  // SPI MOSI (Master Out Slave In)
+#define EPD_CS 21    // Chip Select
+#define EPD_DC 4     // Data/Command
+#define EPD_RST 5    // Reset
+#define EPD_BUSY 6   // Busy
+
+#define SPI_MISO 7  // SPI MISO, shared between SD card and display (Master In Slave Out)
+
+#define BAT_GPIO0 0  // Battery voltage
+
+#define UART0_RXD 20  // Used for USB connection detection
+
+class HalGPIO {
+#if CROSSPOINT_EMULATED == 0
+  InputManager inputMgr;
+#endif
+
+ public:
+  HalGPIO() = default;
+
+  // Start button GPIO and setup SPI for screen and SD card
+  void begin();
+
+  // Button input methods
+  void update();
+  bool isPressed(uint8_t buttonIndex) const;
+  bool wasPressed(uint8_t buttonIndex) const;
+  bool wasAnyPressed() const;
+  bool wasReleased(uint8_t buttonIndex) const;
+  bool wasAnyReleased() const;
+  unsigned long getHeldTime() const;
+
+  // Setup wake up GPIO and enter deep sleep
+  void startDeepSleep();
+
+  // Get battery percentage (range 0-100)
+  int getBatteryPercentage() const;
+
+  // Check if USB is connected
+  bool isUsbConnected() const;
+
+  // Check if wakeup was caused by power button press
+  bool isWakeupByPowerButton() const;
+
+  // Button indices
+  static constexpr uint8_t BTN_BACK = 0;
+  static constexpr uint8_t BTN_CONFIRM = 1;
+  static constexpr uint8_t BTN_LEFT = 2;
+  static constexpr uint8_t BTN_RIGHT = 3;
+  static constexpr uint8_t BTN_UP = 4;
+  static constexpr uint8_t BTN_DOWN = 5;
+  static constexpr uint8_t BTN_POWER = 6;
+};

src/MappedInputManager.cpp

@@ -2,103 +2,77 @@
 
 #include "CrossPointSettings.h"
 
-decltype(InputManager::BTN_BACK) MappedInputManager::mapButton(const Button button) const {
+namespace {
+using ButtonIndex = uint8_t;
+
+struct FrontLayoutMap {
+  ButtonIndex back;
+  ButtonIndex confirm;
+  ButtonIndex left;
+  ButtonIndex right;
+};
+
+struct SideLayoutMap {
+  ButtonIndex pageBack;
+  ButtonIndex pageForward;
+};
+
+// Order matches CrossPointSettings::FRONT_BUTTON_LAYOUT.
+constexpr FrontLayoutMap kFrontLayouts[] = {
+    {HalGPIO::BTN_BACK, HalGPIO::BTN_CONFIRM, HalGPIO::BTN_LEFT, HalGPIO::BTN_RIGHT},
+    {HalGPIO::BTN_LEFT, HalGPIO::BTN_RIGHT, HalGPIO::BTN_BACK, HalGPIO::BTN_CONFIRM},
+    {HalGPIO::BTN_CONFIRM, HalGPIO::BTN_LEFT, HalGPIO::BTN_BACK, HalGPIO::BTN_RIGHT},
+    {HalGPIO::BTN_BACK, HalGPIO::BTN_CONFIRM, HalGPIO::BTN_RIGHT, HalGPIO::BTN_LEFT},
+};
+
+// Order matches CrossPointSettings::SIDE_BUTTON_LAYOUT.
+constexpr SideLayoutMap kSideLayouts[] = {
+    {HalGPIO::BTN_UP, HalGPIO::BTN_DOWN},
+    {HalGPIO::BTN_DOWN, HalGPIO::BTN_UP},
+};
+}  // namespace
+
+bool MappedInputManager::mapButton(const Button button, bool (HalGPIO::*fn)(uint8_t) const) const {
   const auto frontLayout = static_cast<CrossPointSettings::FRONT_BUTTON_LAYOUT>(SETTINGS.frontButtonLayout);
   const auto sideLayout = static_cast<CrossPointSettings::SIDE_BUTTON_LAYOUT>(SETTINGS.sideButtonLayout);
+  const auto& front = kFrontLayouts[frontLayout];
+  const auto& side = kSideLayouts[sideLayout];
 
   switch (button) {
     case Button::Back:
-      switch (frontLayout) {
+      return (gpio.*fn)(front.back);
-        case CrossPointSettings::LEFT_RIGHT_BACK_CONFIRM:
-          return InputManager::BTN_LEFT;
-        case CrossPointSettings::LEFT_BACK_CONFIRM_RIGHT:
-          return InputManager::BTN_CONFIRM;
-        case CrossPointSettings::BACK_CONFIRM_LEFT_RIGHT:
-          /* fall through */
-        case CrossPointSettings::BACK_CONFIRM_RIGHT_LEFT:
-          /* fall through */
-        default:
-          return InputManager::BTN_BACK;
-      }
     case Button::Confirm:
-      switch (frontLayout) {
+      return (gpio.*fn)(front.confirm);
-        case CrossPointSettings::LEFT_RIGHT_BACK_CONFIRM:
-          return InputManager::BTN_RIGHT;
-        case CrossPointSettings::LEFT_BACK_CONFIRM_RIGHT:
-          return InputManager::BTN_LEFT;
-        case CrossPointSettings::BACK_CONFIRM_LEFT_RIGHT:
-          /* fall through */
-        case CrossPointSettings::BACK_CONFIRM_RIGHT_LEFT:
-          /* fall through */
-        default:
-          return InputManager::BTN_CONFIRM;
-      }
     case Button::Left:
-      switch (frontLayout) {
+      return (gpio.*fn)(front.left);
-        case CrossPointSettings::LEFT_RIGHT_BACK_CONFIRM:
-          /* fall through */
-        case CrossPointSettings::LEFT_BACK_CONFIRM_RIGHT:
-          return InputManager::BTN_BACK;
-        case CrossPointSettings::BACK_CONFIRM_RIGHT_LEFT:
-          return InputManager::BTN_RIGHT;
-        case CrossPointSettings::BACK_CONFIRM_LEFT_RIGHT:
-          /* fall through */
-        default:
-          return InputManager::BTN_LEFT;
-      }
     case Button::Right:
-      switch (frontLayout) {
+      return (gpio.*fn)(front.right);
-        case CrossPointSettings::LEFT_RIGHT_BACK_CONFIRM:
-          return InputManager::BTN_CONFIRM;
-        case CrossPointSettings::BACK_CONFIRM_RIGHT_LEFT:
-          return InputManager::BTN_LEFT;
-        case CrossPointSettings::BACK_CONFIRM_LEFT_RIGHT:
-          /* fall through */
-        case CrossPointSettings::LEFT_BACK_CONFIRM_RIGHT:
-          /* fall through */
-        default:
-          return InputManager::BTN_RIGHT;
-      }
     case Button::Up:
-      return InputManager::BTN_UP;
+      return (gpio.*fn)(HalGPIO::BTN_UP);
     case Button::Down:
-      return InputManager::BTN_DOWN;
+      return (gpio.*fn)(HalGPIO::BTN_DOWN);
     case Button::Power:
-      return InputManager::BTN_POWER;
+      return (gpio.*fn)(HalGPIO::BTN_POWER);
     case Button::PageBack:
-      switch (sideLayout) {
+      return (gpio.*fn)(side.pageBack);
-        case CrossPointSettings::NEXT_PREV:
-          return InputManager::BTN_DOWN;
-        case CrossPointSettings::PREV_NEXT:
-          /* fall through */
-        default:
-          return InputManager::BTN_UP;
-      }
     case Button::PageForward:
-      switch (sideLayout) {
+      return (gpio.*fn)(side.pageForward);
-        case CrossPointSettings::NEXT_PREV:
-          return InputManager::BTN_UP;
-        case CrossPointSettings::PREV_NEXT:
-          /* fall through */
-        default:
-          return InputManager::BTN_DOWN;
-      }
   }
 
-  return InputManager::BTN_BACK;
+  return false;
 }
 
-bool MappedInputManager::wasPressed(const Button button) const { return inputManager.wasPressed(mapButton(button)); }
+bool MappedInputManager::wasPressed(const Button button) const { return mapButton(button, &HalGPIO::wasPressed); }
 
-bool MappedInputManager::wasReleased(const Button button) const { return inputManager.wasReleased(mapButton(button)); }
+bool MappedInputManager::wasReleased(const Button button) const { return mapButton(button, &HalGPIO::wasReleased); }
 
-bool MappedInputManager::isPressed(const Button button) const { return inputManager.isPressed(mapButton(button)); }
+bool MappedInputManager::isPressed(const Button button) const { return mapButton(button, &HalGPIO::isPressed); }
 
-bool MappedInputManager::wasAnyPressed() const { return inputManager.wasAnyPressed(); }
+bool MappedInputManager::wasAnyPressed() const { return gpio.wasAnyPressed(); }
 
-bool MappedInputManager::wasAnyReleased() const { return inputManager.wasAnyReleased(); }
+bool MappedInputManager::wasAnyReleased() const { return gpio.wasAnyReleased(); }
 
-unsigned long MappedInputManager::getHeldTime() const { return inputManager.getHeldTime(); }
+unsigned long MappedInputManager::getHeldTime() const { return gpio.getHeldTime(); }
 
 MappedInputManager::Labels MappedInputManager::mapLabels(const char* back, const char* confirm, const char* previous,
                                                          const char* next) const {

src/MappedInputManager.h

@@ -1,6 +1,6 @@
 #pragma once
 
-#include <InputManager.h>
+#include <HalGPIO.h>
 
 class MappedInputManager {
  public:
@@ -13,7 +13,7 @@ class MappedInputManager {
     const char* btn4;
   };
 
-  explicit MappedInputManager(InputManager& inputManager) : inputManager(inputManager) {}
+  explicit MappedInputManager(HalGPIO& gpio) : gpio(gpio) {}
 
   bool wasPressed(Button button) const;
   bool wasReleased(Button button) const;
@@ -24,6 +24,7 @@ class MappedInputManager {
   Labels mapLabels(const char* back, const char* confirm, const char* previous, const char* next) const;
 
  private:
-  InputManager& inputManager;
+  HalGPIO& gpio;
-  decltype(InputManager::BTN_BACK) mapButton(Button button) const;
+
+  bool mapButton(Button button, bool (HalGPIO::*fn)(uint8_t) const) const;
 };

src/activities/boot_sleep/SleepActivity.cpp

@@ -154,7 +154,7 @@ void SleepActivity::renderDefaultSleepScreen() const {
     renderer.invertScreen();
   }
 
-  renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
+  renderer.displayBuffer(HalDisplay::HALF_REFRESH);
 }
 
 void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap, const std::string& bmpPath) const {
@@ -269,7 +269,7 @@ void SleepActivity::renderBitmapSleepScreen(const Bitmap& bitmap, const std::str
     renderer.invertScreen();
   }
 
-  renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
+  renderer.displayBuffer(HalDisplay::HALF_REFRESH);
 
   if (hasGreyscale) {
     // Grayscale LSB pass
@@ -400,7 +400,7 @@ void SleepActivity::renderCoverSleepScreen() const {
 
 void SleepActivity::renderBlankSleepScreen() const {
   renderer.clearScreen();
-  renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
+  renderer.displayBuffer(HalDisplay::HALF_REFRESH);
 }
 
 std::string SleepActivity::getEdgeCachePath(const std::string& bmpPath) {

src/activities/dictionary/EpubWordSelectionActivity.cpp

@@ -1,6 +1,6 @@
 #include "EpubWordSelectionActivity.h"
 
-#include <EInkDisplay.h>
+#include <HalDisplay.h>
 #include <GfxRenderer.h>
 
 #include <algorithm>
@@ -263,5 +263,5 @@ void EpubWordSelectionActivity::render() const {
   const char* sideBottomHint = (currentLineIndex < lastLine) ? "DOWN" : "";
   renderer.drawSideButtonHints(SMALL_FONT_ID, sideTopHint, sideBottomHint, false);  // No border
 
-  renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
+  renderer.displayBuffer(HalDisplay::FAST_REFRESH);
 }

src/activities/reader/EpubReaderActivity.cpp

@@ -89,7 +89,7 @@ void EpubReaderActivity::onEnter() {
     renderer.fillRect(boxX, boxY, boxWidth, boxHeight, false);
     renderer.drawRect(boxX + 5, boxY + 5, boxWidth - 10, boxHeight - 10);
     renderer.drawText(UI_12_FONT_ID, boxX + boxMargin, boxY + boxMargin, "Preparing book... [0%]");
-    renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
+    renderer.displayBuffer(HalDisplay::FAST_REFRESH);
 
     // Generate covers with progress callback
     epub->generateAllCovers([&](int percent) {
@@ -103,7 +103,7 @@ void EpubReaderActivity::onEnter() {
         char progressStr[32];
         snprintf(progressStr, sizeof(progressStr), "Preparing book... [%d%%]", percent);
         renderer.drawText(UI_12_FONT_ID, boxX + boxMargin, boxY + boxMargin, progressStr);
-        renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
+        renderer.displayBuffer(HalDisplay::FAST_REFRESH);
       }
     });
   }
@@ -717,7 +717,7 @@ void EpubReaderActivity::renderScreen() {
       auto progressCallback = [this, barX, barY, barWidth, barHeight](int progress) {
         const int fillWidth = (barWidth - 2) * progress / 100;
         renderer.fillRect(barX + 1, barY + 1, fillWidth, barHeight - 2, true);
-        renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
+        renderer.displayBuffer(HalDisplay::FAST_REFRESH);
       };
 
       if (!section->createSectionFile(SETTINGS.getReaderFontId(), SETTINGS.getReaderLineCompression(),
@@ -835,7 +835,7 @@ void EpubReaderActivity::renderContents(std::unique_ptr<Page> page, const int or
 
   renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
   if (pagesUntilFullRefresh <= 1) {
-    renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
+    renderer.displayBuffer(HalDisplay::HALF_REFRESH);
     pagesUntilFullRefresh = SETTINGS.getRefreshFrequency();
   } else {
     renderer.displayBuffer();

src/activities/reader/TxtReaderActivity.cpp

@@ -85,7 +85,7 @@ void TxtReaderActivity::onEnter() {
     renderer.fillRect(boxX, boxY, boxWidth, boxHeight, false);
     renderer.drawRect(boxX + 5, boxY + 5, boxWidth - 10, boxHeight - 10);
     renderer.drawText(UI_12_FONT_ID, boxX + boxMargin, boxY + boxMargin, "Preparing book... [0%]");
-    renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
+    renderer.displayBuffer(HalDisplay::FAST_REFRESH);
 
     // Generate covers with progress callback
     (void)txt->generateAllCovers([&](int percent) {
@@ -99,7 +99,7 @@ void TxtReaderActivity::onEnter() {
         char progressStr[32];
         snprintf(progressStr, sizeof(progressStr), "Preparing book... [%d%%]", percent);
         renderer.drawText(UI_12_FONT_ID, boxX + boxMargin, boxY + boxMargin, progressStr);
-        renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
+        renderer.displayBuffer(HalDisplay::FAST_REFRESH);
       }
     });
   }
@@ -339,7 +339,7 @@ void TxtReaderActivity::buildPageIndex() {
       // Fill progress bar
       const int fillWidth = (barWidth - 2) * progressPercent / 100;
       renderer.fillRect(barX + 1, barY + 1, fillWidth, barHeight - 2, true);
-      renderer.displayBuffer(EInkDisplay::FAST_REFRESH);
+      renderer.displayBuffer(HalDisplay::FAST_REFRESH);
     }
 
     // Yield to other tasks periodically
@@ -571,7 +571,7 @@ void TxtReaderActivity::renderPage() {
   renderStatusBar(orientedMarginRight, orientedMarginBottom, orientedMarginLeft);
 
   if (pagesUntilFullRefresh <= 1) {
-    renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
+    renderer.displayBuffer(HalDisplay::HALF_REFRESH);
     pagesUntilFullRefresh = SETTINGS.getRefreshFrequency();
   } else {
     renderer.displayBuffer();

src/activities/util/FullScreenMessageActivity.h

@@ -1,6 +1,6 @@
 #pragma once
-#include <EInkDisplay.h>
 #include <EpdFontFamily.h>
+#include <HalDisplay.h>
 
 #include <string>
 #include <utility>
@@ -10,12 +10,12 @@
 class FullScreenMessageActivity final : public Activity {
   std::string text;
   EpdFontFamily::Style style;
-  EInkDisplay::RefreshMode refreshMode;
+  HalDisplay::RefreshMode refreshMode;
 
  public:
   explicit FullScreenMessageActivity(GfxRenderer& renderer, MappedInputManager& mappedInput, std::string text,
                                      const EpdFontFamily::Style style = EpdFontFamily::REGULAR,
-                                     const EInkDisplay::RefreshMode refreshMode = EInkDisplay::FAST_REFRESH)
+                                     const HalDisplay::RefreshMode refreshMode = HalDisplay::FAST_REFRESH)
       : Activity("FullScreenMessage", renderer, mappedInput),
         text(std::move(text)),
         style(style),

src/main.cpp

@@ -1,9 +1,9 @@
 #include <Arduino.h>
 #include <BitmapHelpers.h>
-#include <EInkDisplay.h>
 #include <Epub.h>
 #include <GfxRenderer.h>
-#include <InputManager.h>
+#include <HalDisplay.h>
+#include <HalGPIO.h>
 #include <SDCardManager.h>
 #include <SPI.h>
 #include <builtinFonts/all.h>
@@ -32,23 +32,10 @@
 #include "fontIds.h"
 #include "images/LockIcon.h"
 
-#define SPI_FQ 40000000
+HalDisplay display;
-// Display SPI pins (custom pins for XteinkX4, not hardware SPI defaults)
+HalGPIO gpio;
-#define EPD_SCLK 8   // SPI Clock
+MappedInputManager mappedInputManager(gpio);
-#define EPD_MOSI 10  // SPI MOSI (Master Out Slave In)
+GfxRenderer renderer(display);
-#define EPD_CS 21    // Chip Select
-#define EPD_DC 4     // Data/Command
-#define EPD_RST 5    // Reset
-#define EPD_BUSY 6   // Busy
-
-#define UART0_RXD 20  // Used for USB connection detection
-
-#define SD_SPI_MISO 7
-
-EInkDisplay einkDisplay(EPD_SCLK, EPD_MOSI, EPD_CS, EPD_DC, EPD_RST, EPD_BUSY);
-InputManager inputManager;
-MappedInputManager mappedInputManager(inputManager);
-GfxRenderer renderer(einkDisplay);
 Activity* currentActivity;
 
 // Fonts
@@ -221,7 +208,7 @@ void checkForFlashCommand() {
         renderer.drawImageRotated(LockIcon, iconX, iconY, LOCK_ICON_WIDTH, LOCK_ICON_HEIGHT, rotation);
 
         // Use full refresh for clean display before flash overwrites firmware
-        renderer.displayBuffer(EInkDisplay::HALF_REFRESH);
+        renderer.displayBuffer(HalDisplay::HALF_REFRESH);
       }
       flashCmdBuffer = "";
     } else if (c != '\r') {
@@ -272,21 +259,20 @@ void verifyPowerButtonDuration() {
   const uint16_t calibratedPressDuration =
       (calibration < SETTINGS.getPowerButtonDuration()) ? SETTINGS.getPowerButtonDuration() - calibration : 1;
 
-  inputManager.update();
+  gpio.update();
-  // Verify the user has actually pressed
   // Needed because inputManager.isPressed() may take up to ~500ms to return the correct state
-  while (!inputManager.isPressed(InputManager::BTN_POWER) && millis() - start < 1000) {
+  while (!gpio.isPressed(HalGPIO::BTN_POWER) && millis() - start < 1000) {
     delay(10);  // only wait 10ms each iteration to not delay too much in case of short configured duration.
-    inputManager.update();
+    gpio.update();
   }
 
   t2 = millis();
-  if (inputManager.isPressed(InputManager::BTN_POWER)) {
+  if (gpio.isPressed(HalGPIO::BTN_POWER)) {
     do {
       delay(10);
-      inputManager.update();
+      gpio.update();
-    } while (inputManager.isPressed(InputManager::BTN_POWER) && inputManager.getHeldTime() < calibratedPressDuration);
+    } while (gpio.isPressed(HalGPIO::BTN_POWER) && gpio.getHeldTime() < calibratedPressDuration);
-    abort = inputManager.getHeldTime() < calibratedPressDuration;
+    abort = gpio.getHeldTime() < calibratedPressDuration;
   } else {
     abort = true;
   }
@@ -294,16 +280,15 @@ void verifyPowerButtonDuration() {
   if (abort) {
     // Button released too early. Returning to sleep.
     // IMPORTANT: Re-arm the wakeup trigger before sleeping again
-    esp_deep_sleep_enable_gpio_wakeup(1ULL << InputManager::POWER_BUTTON_PIN, ESP_GPIO_WAKEUP_GPIO_LOW);
+    gpio.startDeepSleep();
-    esp_deep_sleep_start();
   }
 }
 
 void waitForPowerRelease() {
-  inputManager.update();
+  gpio.update();
-  while (inputManager.isPressed(InputManager::BTN_POWER)) {
+  while (gpio.isPressed(HalGPIO::BTN_POWER)) {
     delay(50);
-    inputManager.update();
+    gpio.update();
   }
 }
 
@@ -312,14 +297,11 @@ void enterDeepSleep() {
   exitActivity();
   enterNewActivity(new SleepActivity(renderer, mappedInputManager));
 
-  einkDisplay.deepSleep();
+  display.deepSleep();
   Serial.printf("[%lu] [   ] Power button press calibration value: %lu ms\n", millis(), t2 - t1);
   Serial.printf("[%lu] [   ] Entering deep sleep.\n", millis());
-  esp_deep_sleep_enable_gpio_wakeup(1ULL << InputManager::POWER_BUTTON_PIN, ESP_GPIO_WAKEUP_GPIO_LOW);
+
-  // Ensure that the power button has been released to avoid immediately turning back on if you're holding it
+  gpio.startDeepSleep();
-  waitForPowerRelease();
-  // Enter Deep Sleep
-  esp_deep_sleep_start();
 }
 
 void onGoHome();
@@ -444,7 +426,7 @@ void onGoHome() {
 }
 
 void setupDisplayAndFonts() {
-  einkDisplay.begin();
+  display.begin();
   Serial.printf("[%lu] [   ] Display initialized\n", millis());
   renderer.insertFont(BOOKERLY_14_FONT_ID, bookerly14FontFamily);
 #ifndef OMIT_FONTS
@@ -466,45 +448,24 @@ void setupDisplayAndFonts() {
   Serial.printf("[%lu] [   ] Fonts setup\n", millis());
 }
 
-bool isUsbConnected() {
-  // U0RXD/GPIO20 reads HIGH when USB is connected
-  return digitalRead(UART0_RXD) == HIGH;
-}
-
-bool isWakeupByPowerButton() {
-  const auto wakeupCause = esp_sleep_get_wakeup_cause();
-  const auto resetReason = esp_reset_reason();
-  if (isUsbConnected()) {
-    return wakeupCause == ESP_SLEEP_WAKEUP_GPIO;
-  } else {
-    return (wakeupCause == ESP_SLEEP_WAKEUP_UNDEFINED) && (resetReason == ESP_RST_POWERON);
-  }
-}
-
 void setup() {
   t1 = millis();
 
+  gpio.begin();
+
   // Always initialize Serial - safe on ESP32-C3 USB CDC even without USB connected
   // (the peripheral just remains idle).
-  pinMode(UART0_RXD, INPUT);
   Serial.begin(115200);
 
   // Only wait for terminal connection if USB is physically connected
   // This allows catching early debug logs when a serial monitor is attached
-  if (isUsbConnected()) {
+  if (gpio.isUsbConnected()) {
     unsigned long start = millis();
     while (!Serial && (millis() - start) < 3000) {
       delay(10);
     }
   }
 
-  inputManager.begin();
-  // Initialize pins
-  pinMode(BAT_GPIO0, INPUT);
-
-  // Initialize SPI with custom pins
-  SPI.begin(EPD_SCLK, SD_SPI_MISO, EPD_MOSI, EPD_CS);
-
   // SD Card Initialization
   // We need 6 open files concurrently when parsing a new chapter
   if (!SdMan.begin()) {
@@ -521,7 +482,7 @@ void setup() {
   // Apply bezel compensation from settings
   renderer.setBezelCompensation(SETTINGS.bezelCompensation, SETTINGS.bezelCompensationEdge);
 
-  if (isWakeupByPowerButton()) {
+  if (gpio.isWakeupByPowerButton()) {
     // For normal wakeups, verify power button press duration
     Serial.printf("[%lu] [   ] Verifying power button press duration\n", millis());
     verifyPowerButtonDuration();
@@ -561,7 +522,7 @@ void loop() {
   const unsigned long loopStartTime = millis();
   static unsigned long lastMemPrint = 0;
 
-  inputManager.update();
+  gpio.update();
 
   if (Serial && millis() - lastMemPrint >= 10000) {
     // Basic heap info
@@ -579,8 +540,7 @@ void loop() {
 
   // Check for any user activity (button press or release) or active background work
   static unsigned long lastActivityTime = millis();
-  if (inputManager.wasAnyPressed() || inputManager.wasAnyReleased() ||
+  if (gpio.wasAnyPressed() || gpio.wasAnyReleased() || (currentActivity && currentActivity->preventAutoSleep())) {
-      (currentActivity && currentActivity->preventAutoSleep())) {
     lastActivityTime = millis();  // Reset inactivity timer
   }
 
@@ -592,8 +552,7 @@ void loop() {
     return;
   }
 
-  if (inputManager.isPressed(InputManager::BTN_POWER) &&
+  if (gpio.isPressed(HalGPIO::BTN_POWER) && gpio.getHeldTime() > SETTINGS.getPowerButtonDuration()) {
-      inputManager.getHeldTime() > SETTINGS.getPowerButtonDuration()) {
     enterDeepSleep();
     // This should never be hit as `enterDeepSleep` calls esp_deep_sleep_start
     return;