ESP32-P4 MIPI DSI LCD Demo

This project demonstrates how to initialize and drive a 1280×720 MIPI DSI LCD panel using an ESP32-P4 development kit with PSRAM enabled and MIPI DPI + DSI interface.

It includes:

• Powering the MIPI DSI PHY via LDO
• Setting up the DSI bus and DBI interface
• Initializing the LCD panel
• Drawing a software-generated color bar
• Displaying a hardware color pattern

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🧰 Requirements

• ESP32-P4-Module-DEV-KIT
• Waveshare MIPI DSI 7" LCD (or similar)
• ESP-IDF v5.2 or later
• LCD resolution: 1280x720
• External PSRAM enabled
• Sufficient I2C and GPIO wiring if required for initialization
• LCD backlight control (optional)

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🛠️ Configuration

Ensure the following are enabled in menuconfig:

Component config → ESP System Settings → [*] Support for external, SPI-connected RAM

Also verify:

• PSRAM is large enough for framebuffer(s)
• Pixel clock isn't too high for PSRAM (≤ 40 MHz recommended)

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⚙️ Pin Definitions

Signal	GPIO
LCD RESET	-1 (disabled) or GPIO27
Backlight	-1 (disabled)
I2C SDA/SCL	GPIO7 / GPIO8 (by default)

Adjust as needed in your project configuration.

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📁 Project Structure

• test_init_lcd()
  Initializes LDO, MIPI DSI bus, DBI IO, and the LCD panel.

• test_draw_color_bar()
  Draws a vertical color bar using software rendering.

• app_main()
  Entry point: initializes LCD, shows hardware and software color bars, then deinitializes.

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💡 Notes

• The framebuffer is allocated in PSRAM using heap_caps_calloc() with MALLOC_CAP_DMA.
• A refresh semaphore ensures synchronization between software rendering and DPI refresh.
• Double buffering is supported but not explicitly enabled in this example.

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🖼️ Display Output

The program:

1. Initializes the panel and turns it on
2. Shows a hardware-drawn horizontal color bar pattern
3. Then shows a custom-drawn software color bar using DMA
4. Waits a few seconds before deinitializing

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🚫 Known Issues

• If pixel clock (pclk_hz) is too high, DMA underruns will occur.
• Ensure .psram_trans_align and buffer alignment are correct.
• DSI configuration must match the panel datasheet (number of lanes, timings, etc.).

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✅ Example Output (Log)

I (324) DEBUG +++++++++ log : : New panel I (324) Waveshare DSI: version: 1.0.6 I (334) i2c_bus: I2C Bus V2 uses the externally initialized bus handle I (345) MIPI DSI PHY Powered on I (351) Install panel IO I (359) Install LCD driver of dsi - OK I (365) Show color bar pattern drawn by hardware I (378) Show color bar drawn by software I (398) End of test

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🧪 Optional Features to Try

• Pixel-by-pixel test (uncomment in app_main)
• Double framebuffer (.num_frame_buffers = 2)
• Use esp_cache_msync() when drawing from PSRAM directly

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📜 License

MIT — use this freely for personal or commercial projects.

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🤝 Contributing

Feel free to fork, modify, and submit PRs if you improve performance, compatibility, or add new panel support.

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🧾 Credits

• Based on ESP-IDF MIPI DSI and LCD component APIs
• Tested on ESP32-P4 with Waveshare 7" DSI display

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