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+---
+title: "Esp32 OLED Counter Display"
+date: 2025-11-10T19:10:33+02:00
+tags: []
+author: "Elias Ahokas"
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+---
+
+![Project working](photo_2025-11-10_15-36-01.jpg)
+
+Integrating LVGL embedded graphics library with SSD1306 OLED display on ESP32.
+
+[Source code](https://git.sirian.me/sirian/oled-counter-esp32/src/branch/main)
+
+## Project goal
+
+Get LVGL working on a 128x64 monochrome OLED display connected to ESP32 with I2C. Quick googling resulted only in outdated libraries. This implementation uses the latest libraries to ensure future proofing.
+
+## Main challenge
+
+LVGL outputs pixels in a linear framebuffer format but the display uses page addressing where the screen is divided into 8 horizontal pages of 128x8 pixels. Required implementing a custom flush callback to convert between these formats.
+
+## Implementation
+
+- Custom I2C driver for SSD1306 using ESP-IDF's master driver API
+- Multi-threaded FreeRTOS architecture separating rendering, display updates and application logic
+- Pixel format conversion algorithm for transforming LVGL's I1 framebuffer to SSD1306 page format
+- Queue based page transmission system for non blocking I2C operations
+- Semaphore protected flush pipeline ensuring thread safe rendering