Any experience with Waveshare E-ink Displays?



  • I have been given one of these Waveshare 4.2 Inch e-paper module and wonder if anyone has had any experience at trying to get them to work with an Omega?

    It supports a variety of platforms like RPi Arduno and STM32 and uses a SPI interface.

    Python and C libs are available for the Pi and are GPL2

    Any thoughts ?

    Thanks.



  • @T-NT well, spi is for the most part broken you could spend some time searching the forum for the details. unfortunately the issues are most obvious when using oled and i would guess relatively large [4.2"] e-paper screens. but, i have a particle photon that drives a small one ok. i've seen a teensy 3.6 work well with them also. those are nice screens.
    this guy has a pretty good understanding of them,
    http://benkrasnow.blogspot.com/2017/10/fast-partial-refresh-on-42-e-paper.html



  • @Douglas-Kryder

    Why is SPI so broken? I know pulling some pins high will stop the Omega from booting but is it more than that ?

    Thanks for the link I'll check it out.



  • @T-NT just type spi into the search box in the upper right corner and read of others findings on spi on the omegas



  • There are almost certainly ways to make this work, but they may take some non-trivial engineering.

    • Understand and work around the SPI issues. They mostly have to do with simultaneous write/read operations and long transfers, both of which can usually be avoided at the cost of some efficiency
    • Proxy the SPI through something else, for example a fixed-function chip (FTDI, etc) or a small MCU, hanging off either the USB or one of the UARTs
    • See if you can use the I2S interface instead - this is normally meant to move audio data but it is not dissimilar to SPI. Many chips have offered functional blocks that did both SPI and I2S by configuring different details, which may be well within the range of what you can do with clever software
    • Bitbang SPI on arbitrary GPIOs. Probably slow, though you can do the actually twiddling in kernel mode

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