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/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;
+};