E-Ink (Waveshare) Displays Support

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fvolk
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E-Ink (Waveshare) Displays Support

Unread post by fvolk » Fri Jul 05, 2019 2:12 am

E-ink displays are useful for data that has a low refresh rate (e.g. room temperature).
Odroids would be nice low-power drivers to drive E-ink displays.
From my search Waveshare displays seem to be a common brand, they are attached via SPI.
Search in this forum leads to following thread, which seemed to have died: viewtopic.php?f=115&t=20158

I'd like to attach an E-Ink display to my C2 or H2.
Any plans to support these or provide information how to do these?

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Re: E-Ink (Waveshare) Displays Support

Unread post by odroid » Fri Jul 05, 2019 9:45 am

C2 has no hardware SPI.
H2 has no hardware/software SPI. H2 has only UART and I2C.

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Re: E-Ink (Waveshare) Displays Support

Unread post by fvolk » Sat Jul 06, 2019 3:31 am

So no SPI to attach directly to, and as the thread didn't go anywhere I guess there is no easy workaround :-/

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Re: E-Ink (Waveshare) Displays Support

Unread post by fvolk » Thu Jul 25, 2019 9:22 pm

Actually, looking again, there are 4 Waveshare E-paper displays that claim multibus USB/SPI/I80/I2C interface support https://www.waveshare.com/wiki/Category:I80_interface
Unfortunately these products are as HATs for the RPi.
But if it works on the RPi and there is some example code, it should be possible to port it to Odroid and use via USB/I2C? (although they say I2C is too slow)

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Re: E-Ink (Waveshare) Displays Support

Unread post by mh-g » Sun Dec 01, 2019 3:18 am

The Odroid C2 may be missing hardware SPI, but SW SPI is working just fine. I connected a Waveshare 4.2 inch (bw) e-ink and got it working quite quickly.

My OS:
$ uname -a
Linux media-staging 3.16.75-47 #1 SMP PREEMPT Sat Oct 19 14:21:52 -03 2019 aarch64 aarch64 aarch64 GNU/Linux
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.3 LTS
Release: 18.04
Codename: bionic

I followed these guides (in this order), but used python3, pip3 instead of python, pip:
https://wiki.odroid.com/odroid-c2/appli ... e/gpio/spi
https://wiki.odroid.com/odroid-c2/appli ... o/wiringpi
https://wiki.odroid.com/odroid-c2/appli ... o/rpi.gpio

Then I worked through the introduction at https://www.waveshare.com/wiki/4.2inch_ ... spberry_Pi. Since the Odroid C2 is no Raspberry, I had to change near end of ./e-Paper/RaspberryPi&JetsonNano/python/lib/waveshare_epd/epdconfig.py:

# if os.path.exists('/sys/bus/platform/drivers/gpiomem-bcm2835'):
implementation = RaspberryPi()
# else:
# implementation = JetsonNano()

Basically just disable the hardware detection and hard code RaspberryPi.

Thereafter the Python example works:
$ sudo python3 ./e-Paper/RaspberryPi&JetsonNano/python/examples/epd_4in2_test.py

The display is crisp and clear.
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