Files

T

Adolfo Reyna adfbef7228 abstracting display, touch and sd

2026-01-28 20:12:41 -05:00

8.9 KiB

Raw Blame History

RP2350 TFT Display with Touch and SD Card Demo

A modular embedded application for RP2350 microcontrollers featuring display, touch, and SD card support with hardware abstraction layers.

Features

Display Abstraction Layer - Support for multiple display types (ST7796, ST7789, E-Paper)
Touch Abstraction Layer - Extensible touch controller support (FT6336U)
SD Card with FatFS - File system support with board-aware initialization
Multi-Board Support - Automatic pin configuration for different RP2350 boards
1-bit Rendering - Memory-efficient monochrome graphics with GUI widgets
Board Configuration - Single configuration file for all hardware settings

Supported Hardware

Boards

Adafruit Feather RP2350 (default)
Raspberry Pi Pico 2
Raspberry Pi Pico 2 W

Displays

ST7796 (480x320 TFT LCD) - Fully implemented
ST7789 - Ready for driver implementation
E-Paper - Ready for driver implementation

Touch Controllers

FT6336U (I2C capacitive touch) - Fully implemented
Extensible for additional controllers

Storage

SD Card via SPI with FatFS file system

Quick Start

Building for Default Board (Feather RP2350)

mkdir -p build
cd build
cmake -G Ninja ..
ninja

Building for Specific Board

cmake -G Ninja -DPICO_BOARD=pico2 ..
ninja

Available boards: adafruit_feather_rp2350, pico2, pico2_w

Building for All Boards

./build_all_boards.sh

Generates:

basic1_adafruit_feather_rp2350.uf2
basic1_pico2.uf2
basic1_pico2_w.uf2

Flashing

Hold BOOTSEL button while connecting USB
Copy the .uf2 file to the mounted drive
Device will automatically reboot and run

Or use the flash script:

./build_and_flash.sh

Project Structure

basic1/
├── basic1.cpp                      # Main application
├── board_config.h                  # Board-specific pin configuration
├── CMakeLists.txt                  # Build configuration
├── build_all_boards.sh             # Multi-board build script
├── build_and_flash.sh              # Build and flash helper
│
├── display/                        # Display and GUI abstraction
│   ├── low_level_display.h         # Display interface
│   ├── low_level_display_*.cpp     # Display implementations
│   ├── low_level_touch.h           # Touch interface
│   ├── low_level_touch_*.cpp       # Touch implementations
│   ├── low_level_render.h/cpp      # 1-bit rendering engine
│   └── low_level_gui.h/cpp         # GUI widgets
│
├── lib/                            # Hardware drivers
│   ├── ft6336u/                    # FT6336U touch driver
│   ├── st7796/                     # ST7796 display driver
│   ├── sd_card/                    # SD card driver with FatFS test
│   └── fatfs/                      # FatFS filesystem
│
├── fonts/                          # Bitmap font definitions
└── fatfs_time.c                    # FatFS timestamp (uses compile time)

Configuration

Board Configuration (`board_config.h`)

All hardware settings are defined per board:

// Display configuration
#define DISPLAY_WIDTH 480
#define DISPLAY_HEIGHT 320
#define DISPLAY_TYPE_SELECTED 0  // DISPLAY_TYPE_ST7796

// Touch configuration
#define TOUCH_TYPE_SELECTED 0  // TOUCH_TYPE_FT6336U
#define TOUCH_SWAP_XY true
#define TOUCH_INVERT_X true
#define TOUCH_INVERT_Y false

// SPI pins for display
#define DISPLAY_SPI_PORT spi1
#define DISPLAY_SCK_PIN  18
#define DISPLAY_MOSI_PIN 19
#define DISPLAY_MISO_PIN 20
#define DISPLAY_CS_PIN   17
// ... more pins

Changing Display Type

Modify DISPLAY_TYPE_SELECTED in board_config.h:

0 = ST7796 (480x320 TFT)
1 = ST7789
2 = E-Paper

Changing Touch Type

Modify TOUCH_TYPE_SELECTED in board_config.h:

0 = FT6336U
1 = None (disable touch)

Touch Coordinate Transformation

Adjust orientation in board_config.h:

#define TOUCH_SWAP_XY true      // Swap X/Y coordinates
#define TOUCH_INVERT_X true     // Invert X axis
#define TOUCH_INVERT_Y false    // Invert Y axis

Architecture

Display Abstraction Layer

Provides a unified interface for different display types:

class LowLevelDisplay {
public:
    virtual bool init() = 0;
    virtual void clear(bool white = true) = 0;
    virtual void draw_buffer(const uint8_t* bit_buffer) = 0;
    virtual void refresh() = 0;
    // ... more methods
    
    static LowLevelDisplay* create(DisplayType type, int width, int height);
};

Usage:

LowLevelDisplay* display = LowLevelDisplay::create(
    (DisplayType)DISPLAY_TYPE_SELECTED, V_WIDTH, V_HEIGHT);
display->init();
display->draw_buffer(buffer);
display->refresh();

Touch Abstraction Layer

Unified interface for touch controllers:

class LowLevelTouch {
public:
    virtual bool init() = 0;
    virtual bool read_touch(TouchData* data) = 0;
    virtual bool is_touched() = 0;
    // ... more methods
    
    static LowLevelTouch* create(TouchType type, int width, int height,
                                 bool swap_xy, bool invert_x, bool invert_y);
};

Usage:

LowLevelTouch* touch = LowLevelTouch::create(
    (TouchType)TOUCH_TYPE_SELECTED, V_WIDTH, V_HEIGHT,
    TOUCH_SWAP_XY, TOUCH_INVERT_X, TOUCH_INVERT_Y);
    
TouchData touch_data;
if (touch->read_touch(&touch_data)) {
    int x = touch_data.points[0].x;
    int y = touch_data.points[0].y;
    // Handle touch
}

SD Card Abstraction

Board-aware initialization:

// Initialize with board configuration
if (sd_card_init_with_board_config()) {
    // Test FatFS functionality
    sd_card_test_fatfs();
}

The test function:

Mounts FatFS
Lists directory contents
Creates and reads test file
Safely unmounts filesystem

Pin Configurations

Adafruit Feather RP2350

Display (SPI1): SCK=18, MOSI=19, MISO=20, CS=17, DC=16, RST=15, BL=14
Touch (I2C0): SDA=4, SCL=5, INT=6, RST=7
SD Card (SPI1): CS=10 (shares SPI with display)

Raspberry Pi Pico 2 / Pico 2 W

Display (SPI0): SCK=2, MOSI=3, MISO=4, CS=5, DC=6, RST=7, BL=8
Touch (I2C0): SDA=12, SCL=13, INT=14, RST=15
SD Card (SPI1): CS=17

Adding New Hardware

Adding a New Display Driver

Create implementation files:

display/low_level_display_mydriver.h
display/low_level_display_mydriver.cpp

Implement the LowLevelDisplay interface

Add to factory in low_level_display_factory.cpp:

case DISPLAY_TYPE_MYDRIVER:
    display = new LowLevelDisplayMyDriver(width, height);
    break;

Update CMakeLists.txt to include new files

Adding a New Touch Controller