PhotoPainter_B E-Paper Photo Frame

PhotoPainter_B is an enhanced firmware for the Waveshare PhotoPainter (B) e-paper photo frame. This project enables automatic slideshow functionality with various operation modes, supporting custom image selection methods.

Features

• Battery-powered e-paper photo frame
• Multiple display modes for different slideshow preferences
• Low power consumption with automatic sleep mode
• Image rotation at fixed intervals (configurable from 1 minute to 24 hours)
• True random image selection in Mode 3 using RP2040 hardware RNG
• Settings configuration via settings.txt file
• Charging status indication with LED
• Low battery protection
• Support for SD card to store images

Operation Modes

The PhotoPainter_B supports four operation modes:

1. Mode 0: Automatically scans the pic folder on the SD card, sorts the filenames alphabetically, and displays them sequentially.
2. Mode 1: Automatically scans the pic folder on the SD card, displays images in the order they are found (unsorted).
3. Mode 2: Uses a user-created fileList.txt file with custom paths to images. No file limit, allowing for a large collection of images.
4. Mode 3: Same as Mode 2, but selects the next image randomly from the fileList.txt file using true hardware random number generation.

Settings

You can now configure the device using a settings.txt file on the SD card. If this file doesn't exist, it will be created automatically with default values.

Settings File Format

The settings.txt file uses a simple key-value format:

Mode=3
TimeInterval=720
CurrentIndex=1

• Mode: Operation mode (0-3) as described above
• TimeInterval: Time between image changes in minutes (1-1440, default is 720 = 12 hours)
• CurrentIndex: Current position in the image list (automatically updated)

You can edit this file manually to change settings without modifying the code.

Hardware Configuration

• Display: 7.3-inch e-paper display
• Processor: Raspberry Pi Pico (RP2040)
• Storage: MicroSD card for image storage
• Power: Built-in rechargeable battery with USB-C charging

Timing Configuration

The image rotation interval can now be set directly in the settings.txt file:

TimeInterval=720  # 12 hours (in minutes)

For shorter intervals:

TimeInterval=60   # 1 hour
TimeInterval=5    # 5 minutes
TimeInterval=1    # 1 minute

Note: When using very short intervals (e.g., 1 minute), the device should be connected to power. In battery mode, the device powers off between updates and requires hardware support to wake up from RTC alarm.

Random Image Selection

Mode 3 now uses the RP2040's hardware ring oscillator as a source of true randomness, ensuring a better distribution of random images and avoiding repetition.

Battery Protection

The device will automatically power off when the battery voltage falls below 3.1V:

if(measureVBAT() < 3.1) {   // Low battery threshold
    // Power off sequence
}

File Structure

For Mode 0 and Mode 1, place your images in the pic folder at the root of the SD card.

For Mode 2 and Mode 3, create a file named fileList.txt at the root of the SD card with each line containing a path to an image file, for example:

pic/image1.bmp
pic/image2.bmp
pic/subfolder/image3.bmp

Image Conversion

For the best display quality on the e-paper screen, images should be properly converted. Please use the dedicated image conversion tool from:

PhotoPainter_image_converter

This tool provides:

• Optimal image formatting for e-ink displays
• Orientation filtering (portrait/landscape)
• Image enhancement options (brightness, contrast, saturation)
• Optional date display on images
• Support for multiple image formats including HEIC
• Batch processing with progress indication

Usage

1. Convert your images using the PhotoPainter_image_converter
2. Copy the converted images to the SD card's pic folder
3. If using Mode 2 or 3, create a fileList.txt file listing the images
4. (Optional) Create or modify settings.txt to customize operation mode and timing
5. Insert the SD card into the PhotoPainter device
6. Power on the device and enjoy your slideshows

Troubleshooting

• If the display doesn't update, check the battery level
• If images don't appear, verify the SD card is properly formatted (FAT32 recommended)
• For Mode 2 and 3, make sure the paths in fileList.txt are correct
• If settings aren't being saved, check SD card permissions and ensure it's not write-protected
• For 1-minute intervals, keep the device connected to power to ensure it stays active
• Images must be in a compatible format (BMP files work best with this firmware)
• If you experience issues, check the debug output when connected via USB

Recent Updates

• Added settings.txt file for easy configuration
• Improved random image selection using hardware RNG
• Enhanced mount/unmount handling for more reliable file operations
• Better error recovery and validation for all user inputs
• Improved RTC alarm handling
• Added comprehensive debug logging

License

This project is available under open-source licensing. Feel free to modify and enhance the code for your own use.