Seven color e-paper photo frame

Battery operated photo frame using the Advanced Color ePaper (ACeP™) display from Waveshare. The display has seven colors and measure 5.56 inch, 600 by 448 pixels. Overall dimensions: 125.4 x 99.5 x 9mm (WxHxD, depth includes header and display). Display usable area dimensions: 114.9 x 85.8mm (WxH). The images are preprocessed using Floyd-Steinberg dithering to reduce to 7 colors and still have a reasonable quality and stored on a SD-card. An Arduino is used to read from the SD-card and write to the display. lenna.bmp is a ready to use example image.

BOM

• 7 Color ePaper display
• Arduino pro-mini
• SD card reader (images storage)
• LDR (to not change the image in the dark)
• N-channel MOS FET (for example AO3402) (to switch off the SD card reader)
• 2x AA of 2x AAA battery holder
• 3.3 volt mini boost converter (power supply)
• Capacitor 220uF or bigger (power supply filter)
• Capacitor 100nF (power supply filter)
• 3D printed frame

To make the Adruino and SD card reader low power, remove the voltage regulator.

Wire up the Display, and SD-card reader to the Arduino (Uno / Nano / Pro-Mini)

Pins Arduino <=> SD Card module

• 10 - CS / SS
• 11 - MOSI / DI
• 12 - MISO / DO
• 13 - SCK / CLK
• GND - GND
• Vcc - 3.3V

Pins Arduino <=> 7 color e-paper display

• 7 - BUSY
• 8 - RST
• 9 - DC
• 6 - CS
• 13 - CLK
• 11 - DIN
• GND - GND
• Vcc - 3.3V

Prepare the images using Gimp

Start GIMP and drag the image to be processed into the application.

Create a seven color palette

Use the palette editor to create a seven color palette | |Color |Bin |Hex|R,G,B | |---|-------|-------|-----|-----------| |1. |Black |0b000 |0x0 |0,0,0 | |2. |White |0b001 |0x1 |255,255,255| |3. |Green |0b010 |0x2 |0,255,0 | |4. |Blue |0b011 |0x3 |0,0,255 | |5. |Red |0b100 |0x4 |255,0,0 | |6. |Yellow |0b101 |0x5 |255,255,0 | |7. |Orange |0b110 |0x6 |255,128,0 |

<br/> GIMP Palatte Editor dialog

Rearrange the colormap

Make sure that the colors are arranged in the correct order in the Rearrange Colormap dialog.<br/> Main menu or right click image and select

• Colors >
• Map >
• Rearrange Colormap...
• Make sure the colors are ordered as mentioned above in the color palette or the image below, and select OK

<br/> Rearrange Colormap dialog

Resize and crop

Resize to 600 width or 448 height so an 600 by 448 image can be cropped.

Resize

Main menu / right click image and select

• Image >
• Scale Image...
• Provide width and or height
• Select Scale to apply the selection

Crop

'Shift + C' or main menu / right click image and select

• Tools >
• Transform Tools >
• Crop (Shift + C)
• Use mouse and or size and position fields
• Select Enter to apply the crop or Esc to leave the Crop menu

Dither

Main menu / right click image and select

• Image >
• Mode >
• Indexed...
• Use custom pallete
• Select the created 7 color palette
• Select Floyd-Steinberg for Color dithering
• Select Convert

Export as BMP

'Shift + Ctrl + E' or main menu / right click image and select

• File
• Export as (Shift + Ctrl + E)
• Type a filename and give it the bmp extension
• Deselect 'run-length encoding'
• Under 'Compatibility options' select 'Do not write color space information'
• Select Export

<br/> GIMP Export Image as BMP dialog