4.2″ and 7.5″ NFC-powered e-Paper Displays Work without Battery

e-Paper displays have great readability under sunlight, and only consume power when updated. But their refresh rate is limited, and most displays are fairly expensive. One way to reduce the cost is to completely remove the battery from the display, and update it through NFC providing both data and power.

I’ve just found out about that possibility through 4.2″ and 7.5″ displays offered by Waveshare. All you need is a compatible NFC smartphone, or the company’s ST25R3911B NFC Board to power the display and transfer your image of choice. This works best for signs you may need to infrequently update such as menus, daily schedules, conference badges, labels, etc…

Waveshare NFC-powered e-Paper display key features and specifications:

• Screens
  • 7.5″ display
    • 800×480 resolution
    • 2-level greyscale
    • 170° viewing angle
    • Refresh Time – 5s + data transfer time
  • 4.2″ display
    • 400×300 resolution
    • 2-level greyscale
    • 170° viewing angle
    • Refresh Time – 4s + data transfer time
• Wireless Connectivity – NFC
• Power Supply – Wireless over NFC
• Dimensions
  • 4.2″ model: 105.0 x 94.1 x 9.90mm
  • 7.5″ model: 195.84 x 137.68 x 13 mm

Then all you need to do is to install NFCTag app to your Android 4.0+ smartphone, to load and edit images, and transfer them to the display.

It’s been tested successfully with various NFC phones including various models from Samsung, Huawei, Sony, Google Pixel, LG, Xiaomi, and others. But as long as your phone supports NFC, and delivers enough power to the display it should work with any phone. Once the image or processed photo is loaded on the display it will show for weeks until you update the image. The process to update the is demonstrated in the video below.

As an alternative to smartphones, Waveshare also provides ST25R3911B NFC board based on STM32F103R microcontroller and equipped with an OLED display, user buttons, and a MicroSD card socket where you’d put the image to load to the display. It can deliver 1.4 Watt of power. Note the image must be prepared for use on e-Paper display using Floyd-Steinberg dithering algorithm in photo editing software like Photoshop or Gimp.

You’ll find some more details and instructions in the Wiki. The 4.2″ model is sold on Aliexpress for $42.29 shipped with free shipping, and the 7.5″ model for $70.19 from the same shop.

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