Fix: partial refresh, but color still in negative

main/display/eink_display_handler.cpp

@@ -12,16 +12,20 @@
 #define MINIMUM_PIN_SETUP_DELAY_MS 10
 #define MINIMUM_POWER_ON_DELAY_MS 100
 
-static uint8_t black_data[DISPLAY_BUFFER_SIZE]; // all black data
+static uint8_t* DRAW_BUFFER; // 1 bit per pixel
-static uint8_t white_data[DISPLAY_BUFFER_SIZE]; // all white data
+static uint8_t* OLD_DRAW_BUFFER; // 1 bit per pixel
-static uint8_t DRAW_BUFFER[DISPLAY_WIDTH * DISPLAY_HEIGHT / 8]; // 1 bit per pixel
+static uint8_t* black_data;
-static uint8_t OLD_DRAW_BUFFER[DISPLAY_WIDTH * DISPLAY_HEIGHT / 8]; // 1 bit per pixel
+static uint8_t* white_data;
 
 EInkDisplayHandler::EInkDisplayHandler() {
-  memset(black_data, 0xFF, sizeof(black_data)); // eink uses 1 for black
+  black_data = static_cast<uint8_t*>(heap_caps_malloc(DISPLAY_BUFFER_SIZE, MALLOC_CAP_SPIRAM));
-  memset(white_data, 0x00, sizeof(white_data));
+  white_data = static_cast<uint8_t*>(heap_caps_malloc(DISPLAY_BUFFER_SIZE, MALLOC_CAP_SPIRAM));
-  memset(DRAW_BUFFER, 0x00, sizeof(DRAW_BUFFER)); // start with all white (0 = white in e-ink)
+  DRAW_BUFFER = static_cast<uint8_t*>(heap_caps_malloc(DISPLAY_BUFFER_SIZE, MALLOC_CAP_SPIRAM));
-  memset(OLD_DRAW_BUFFER, 0x00, sizeof(OLD_DRAW_BUFFER)); // start with all white (0 = white in e-ink)
+  OLD_DRAW_BUFFER = static_cast<uint8_t*>(heap_caps_malloc(DISPLAY_BUFFER_SIZE, MALLOC_CAP_SPIRAM));
+  memset(black_data, 0xFF, DISPLAY_BUFFER_SIZE); // eink uses 1 for black
+  memset(white_data, 0x00, DISPLAY_BUFFER_SIZE);
+  memset(DRAW_BUFFER, 0x00, DISPLAY_BUFFER_SIZE); // start with all white (0 = white in e-ink)
+  memset(OLD_DRAW_BUFFER, 0x00, DISPLAY_BUFFER_SIZE); // start with all white (0 = white in e-ink)
   draw_buffer_ = DRAW_BUFFER;
   old_buffer_ = OLD_DRAW_BUFFER;
 
@@ -41,6 +45,18 @@ EInkDisplayHandler::~EInkDisplayHandler() {
   if (tp_io_handle_ != nullptr) {
     esp_lcd_panel_io_del(tp_io_handle_);
   }
+  if (black_data != nullptr) {
+    heap_caps_free(black_data);
+  }
+  if (white_data != nullptr) {
+    heap_caps_free(white_data);
+  }
+  if (DRAW_BUFFER != nullptr) {
+    heap_caps_free(DRAW_BUFFER);
+  }
+  if (OLD_DRAW_BUFFER != nullptr) {
+    heap_caps_free(OLD_DRAW_BUFFER);
+  }
 }
 
 esp_err_t EInkDisplayHandler::deep_sleep_display(void) {
@@ -205,27 +221,11 @@ esp_err_t EInkDisplayHandler::full_write(const uint8_t* framebuffer, const bool
   return ESP_OK;
 }
 
+// TODO: Partial refresh is inverted in color
 esp_err_t EInkDisplayHandler::partial_refresh(const uint8_t* incoming_partial_framebuffer, const RefreshArea& incoming_area, const bool is_last_partial_update) {
   ESP_LOGI(TAG, "Starting partial refresh (0.3 seconds)...");
   esp_err_t err = ESP_OK;
 
-
-  {
-    TransactionGuard transaction_guard(this->epd_handler_);
-    err = transaction_guard.begin(pdMS_TO_TICKS(5000));
-    if (err != ESP_OK) {
-      ESP_LOGE(TAG, "Failed to begin transaction for partial refresh: %s", esp_err_to_name(err));
-      return err;
-    }
-    // Wake display from deep sleep INSIDE the transaction to prevent race conditions
-    if (is_deep_sleep_) {
-      err = epd_init_partial_internal_(transaction_guard.transaction_id());
-      if (err != ESP_OK) {
-        ESP_LOGE(TAG, "Failed to initialize EPD for partial refresh: %s", esp_err_to_name(err));
-        return err;
-      }
-    }
-
   write_to_buffer_(incoming_partial_framebuffer, incoming_area);
 
   // Always expand refresh_area_ to include incoming_area
@@ -235,6 +235,27 @@ esp_err_t EInkDisplayHandler::partial_refresh(const uint8_t* incoming_partial_fr
     ESP_LOGI(TAG, "Partial refresh skipped (not last partial update)");
     return ESP_OK;
   }
+  {
+    TransactionGuard transaction_guard(this->epd_handler_);
+    err = transaction_guard.begin(pdMS_TO_TICKS(5000));
+    if (err != ESP_OK) {
+      ESP_LOGE(TAG, "Failed to begin transaction for partial refresh: %s", esp_err_to_name(err));
+      return err;
+    }
+    // Wake display from deep sleep INSIDE the transaction to prevent race conditions
+    if (is_deep_sleep_) {
+      err = epd_init_internal_(transaction_guard.transaction_id());
+      if (err != ESP_OK) {
+        ESP_LOGE(TAG, "Failed to initialize EPD for partial refresh: %s", esp_err_to_name(err));
+        return err;
+      }
+      err = refresh_old_buffer_(transaction_guard.transaction_id());
+      if (err != ESP_OK) {
+        ESP_LOGE(TAG, "Failed to refresh old buffer during partial refresh init: %s", esp_err_to_name(err));
+        return err;
+      }
+    }
+
 
     RefreshArea area = refresh_area_;
     if (area.x1 % 8 != 0 || area.x2 % 8 != 7) {
@@ -248,7 +269,9 @@ esp_err_t EInkDisplayHandler::partial_refresh(const uint8_t* incoming_partial_fr
     const uint32_t area_height = area.y2 - area.y1 + 1;
     const size_t partial_buffer_size = area_width_bytes * area_height;
 
-    uint8_t* partial_buffer = new uint8_t[partial_buffer_size];
+    // uint8_t* partial_buffer = new uint8_t[partial_buffer_size];
+    uint8_t* partial_buffer = static_cast<uint8_t*>(heap_caps_malloc(partial_buffer_size, MALLOC_CAP_DMA | MALLOC_CAP_INTERNAL));
+
     if (partial_buffer == nullptr) {
       ESP_LOGE(TAG, "Failed to allocate partial buffer for partial refresh");
       return ESP_ERR_NO_MEM;
@@ -329,7 +352,7 @@ esp_err_t EInkDisplayHandler::partial_refresh(const uint8_t* incoming_partial_fr
       err = epd_handler_.epd_write_cmd(0x13, transaction_guard.transaction_id());
       if (err != ESP_OK) {
         ESP_LOGE(TAG, "Failed to send new data command for partial refresh: %s", esp_err_to_name(err));
-        delete[] partial_buffer;
+        heap_caps_free(partial_buffer);
         return err;
       }
 
@@ -339,16 +362,19 @@ esp_err_t EInkDisplayHandler::partial_refresh(const uint8_t* incoming_partial_fr
       err = epd_handler_.transfer_spi_data(partial_buffer, partial_buffer_size, transaction_guard.transaction_id());
       if (err != ESP_OK) {
         ESP_LOGE(TAG, "Failed to send partial_buffer data for partial refresh: %s", esp_err_to_name(err));
-        delete[] partial_buffer;
+        heap_caps_free(partial_buffer);
         return err;
       }
+
+      memcpy(old_buffer_, draw_buffer_, DISPLAY_BUFFER_SIZE);
     }
 
     // Clean up partial buffer
-    delete[] partial_buffer;
+    heap_caps_free(partial_buffer);
 
     // Step 6: Trigger partial display refresh (DRF)
-    err = epd_handler_.epd_write_cmd(0x11, transaction_guard.transaction_id());
+    // Use 0x12 (Display Update) command - same as full refresh, per sample code
+    err = epd_handler_.epd_write_cmd(0x12, transaction_guard.transaction_id());
     if (err != ESP_OK) {
       ESP_LOGE(TAG, "Failed to send display refresh command for partial refresh: %s", esp_err_to_name(err));
       return err;
@@ -398,7 +424,6 @@ esp_err_t EInkDisplayHandler::partial_refresh(const uint8_t* incoming_partial_fr
     return err;
   }
 
-  memcpy(old_buffer_, draw_buffer_, DISPLAY_BUFFER_SIZE);
 
   refresh_area_.reset();
 
@@ -702,7 +727,7 @@ esp_err_t EInkDisplayHandler::init_touch_() {
 }
 
 esp_err_t EInkDisplayHandler::refresh_old_buffer_(uint32_t transaction_id) {
-  ESP_LOGI(TAG, "Refreshing display SRAM to match current buffers...");
+  ESP_LOGI(TAG, "Refreshing display SRAM to restore state after wake...");
   esp_err_t err;
 
   err = epd_handler_.epd_write_cmd(0x92, transaction_id); // enter normal mode
@@ -710,7 +735,11 @@ esp_err_t EInkDisplayHandler::refresh_old_buffer_(uint32_t transaction_id) {
     ESP_LOGE(TAG, "Failed to enter normal mode: %s", esp_err_to_name(err));
     return err;
   }
-  // Send command to write old data (0x10)
+
+  // Write OLD data (0x10) as all 0x00 (white in e-ink terms)
+  // This tells the controller: "assume display was all white"
+  // Matches sample's EPD_WhiteScreen_ALL() which uses 0x00 for old SRAM
+  // The differential refresh: old=0 + new=0 → stay white, old=0 + new=1 → drive to black
   err = epd_handler_.epd_write_cmd(0x10, transaction_id);
   if (err != ESP_OK) {
     ESP_LOGE(TAG, "Failed to send old data command: %s", esp_err_to_name(err));
@@ -720,25 +749,25 @@ esp_err_t EInkDisplayHandler::refresh_old_buffer_(uint32_t transaction_id) {
   // Send the old buffer as old data
   err = epd_handler_.transfer_spi_data(old_buffer_, DISPLAY_BUFFER_SIZE, transaction_id);
   if (err != ESP_OK) {
-    ESP_LOGE(TAG, "Failed to send old buffer data: %s", esp_err_to_name(err));
+    ESP_LOGE(TAG, "Failed to send white baseline to old SRAM: %s", esp_err_to_name(err));
     return err;
   }
 
-  // Also write to new data register (0x13) to ensure consistent baseline
+  // Write NEW data (0x13) with the actual display content
-  // This prevents undefined state after hardware reset
+  // This restores the display to show old_buffer_ content
   err = epd_handler_.epd_write_cmd(0x13, transaction_id);
   if (err != ESP_OK) {
     ESP_LOGE(TAG, "Failed to send new data command: %s", esp_err_to_name(err));
     return err;
   }
 
-  // Send the draw buffer as new data (should match old_buffer_ after full refresh)
+  // Send the last displayed content to new SRAM
   err = epd_handler_.transfer_spi_data(old_buffer_, DISPLAY_BUFFER_SIZE, transaction_id);
   if (err != ESP_OK) {
-    ESP_LOGE(TAG, "Failed to send draw buffer data: %s", esp_err_to_name(err));
+    ESP_LOGE(TAG, "Failed to send display content to new SRAM: %s", esp_err_to_name(err));
     return err;
   }
 
-  ESP_LOGI(TAG, "Display SRAM refreshed successfully");
+  ESP_LOGI(TAG, "Display SRAM restored successfully");
   return ESP_OK;
 }