Split heap gate into separate free-memory (50KB) and largest-block (20KB) thresholds based on field measurements. Enable wolfSSL single-precision ECC to use fixed 256-bit arrays instead of heap-allocated fast-math bignums, reducing TLS handshake memory footprint. Reclaim ~7KB by right-sizing ESP timer task stacks and move WiFi code out of IRAM to free ~25-30KB for heap. Add memory audit landmarks for font and EPUB allocations.
Adds residentBytes() and cssRuleCount() methods to track EPUB memory usage including parsed CSS. Enhances memory audit logging with EPUB heap usage, max allocatable block size, and CSS rule count. Implements one-shot heap block map dump on first settled audit to identify fragmentation and long-lived allocations.
Implements reportMemory() methods across SdCardFont, SdCardFontManager, and Section classes to track resident heap usage. Adds heap audit logging in EpubReaderActivity to attribute memory to fonts, framebuffer, section data, and other components for measurement-driven optimization.
Preload glyphs for the next page during idle time to reduce page-turn latency. After a 400ms debounce period, scan the next page in FCM scan mode (no pixels drawn) to cache missing glyphs from SD card, avoiding ~100ms of SD reads during the actual page turn. Prewarm is deferred when rendering is active, heap is low, or during rapid page-flipping.
Buffer JSON file list entries into ~1.4KB batches before sending to avoid one TCP segment per file. This eliminates client delayed ACK delays that were causing large directory listings to take tens of seconds. Falls back to per-entry sends if buffer allocation fails.
Explicitly stop the BLE stack before bringing up WiFi in CrossPointWebServerActivity, FontDownloadActivity, and OtaUpdateActivity. On ESP32-C3, the shared radio and heap between BLE and WiFi stacks causes WiFi to be permanently starved if initialized while NimBLE's ~50KB is still resident, as the WiFi driver sizes its RX/TX buffer pools at init time.
Previously the status bar showed 'BT connecting' until the next page turn. Now monitors connection state in loop() and redraws the status bar immediately when connection completes or disconnects, restoring the chapter/book title. The connecting message now takes over the entire title slot instead of prepending to it.
Introduces non-blocking display refresh methods that allow CPU work (like grayscale rendering) to overlap with the e-ink panel's refresh time. The async path starts the waveform and returns immediately, with the caller responsible for waiting via waitRefreshComplete(). Falls back to blocking refresh when fadingFix is enabled or the panel lacks deferral support.
Changes all sleep screen display refreshes and boot screens from
FULL_REFRESH to HALF_REFRESH to match OEM firmware behavior. The stock
firmware uses a single-pass 0xD7 waveform for sleep screens, not the
multi-flash GC waveform (0xF7) that FULL_REFRESH triggers. For grayscale
mode, HALF_REFRESH is required because the gray nudge LUT is calibrated
against the pixel charge state left by the single-pass waveform; using
FULL_REFRESH causes blotchy noise in gray areas. Also adds X3 wb_gc
passive byte (the one-byte 0x54 to 0x00, matching stock's passive WB
table in the gc nudge bank): Every X3 grayscale render, reader AA,
covers, and the sleep-cover nudge, gets it.
Display a Bluetooth icon in the status bar when BLE is connected. Also optimize memory management by lending the framebuffer instead of immediately tearing down BLE when heap is low, allowing BLE to remain active during rendering.
Temporarily release framebuffer memory during section pagination to reduce heap pressure. The framebuffer can be released before memory-intensive operations and restored afterward, allowing BLE stack startup threshold to be lowered from 80KB to 70KB. Implements RAII-style FrameBufferBuildLoan class to ensure proper cleanup and automatic restart on restoration failure.
Add missingInclude suppression to prevent false positives on fresh CI checkouts where include paths are unresolved. Add inline suppression for constVariableReference warning where cppcheck cannot detect mutations without full include path resolution.
Reduce BLE stack memory usage from ~68KB to ~52KB by disabling unused NimBLE roles (peripheral, broadcaster), limiting connections to 1, and reducing buffer counts for ACL, HCI events, and ATT entries. Remove unused cloud components (esp_insights, esp_rainmaker) that require unavailable server certificates. These changes prevent stack collision with the render shed, eliminating restart flaps on the reader device.
Replace per-page buffer free+realloc pattern with capacity tracking that only reallocates when needed size exceeds current capacity. This prevents heap fragmentation from non-coalescing holes that occurred when each page's freed block rarely fit the next page's allocation. After a few page turns, capacities converge on the book's maximum and page turns stop touching the allocator entirely.
Prevent OOM aborts by shedding BLE stack when free heap drops below 24KB before rendering. Lower BLE start threshold from 100KB to 80KB to match steady-state heap levels (~84KB). Reserve vector capacity upfront in page parsing to avoid reallocation crashes on fragmented heaps. Gate background section builds on heap availability.
Justin Mitchell