CALE is ready to be tested and works stable in ESP8266 and ESP32. This log is to make a remark about my experience with this 7.5" displays of Waveshare

V1 640x384 245760 pixels

Can work with:

• ESP32
• ESP8266

GxEPD : #include <GxGDEW075T8/GxGDEW075T8.cpp>

This first version of Waveshare display that can be found in Alixpress for about 53u$ is a very good candidate for both SoCs. Compression is only supported in ESP32, although is not needed, is only a mean to save some seconds downloading the image.

V2 800x480 384000 pixels (138240 more than V1)

Can work with:

• ESP32

GxEPD : #include <GxGDEW075T7/GxGDEW075T7.cpp>

I tried to compile master of the CALE repository on a ESP8266 and it just restarts all the time. So I left there the GxGDEW075T8 model as a default include for that works for both.
Maybe someone can try to make it work on ESP8266 with different settings, please let me know, but I suspect is using too much memory since they are a lot of pixels.
They are different benefits using ESP32 vs ESP8266. The ESP32 consumes almost double since has 2 cores. But adjusting CPU frequency in plataformio.ini can also be a good way to reduce consumption:

board_build.f_cpu = 80000000L

ESP8266 is a great candidate for this, since it consumes very little, and has the right resources to drive the V1 version of this display and all the other smallers, it's also cheaper than ESP32 so I will highly recommend it as a first choice. Due that it can sleep only max. about 3 hours compared to his bigger brother, I prepared a special branch that sleeps 3 hrs * 8 times if you want to have a calendar that refreshes only once a day saving as much battery as possible:
https://github.com/martinberlin/eink-calendar/blob/esp8266/long-sleep/platformio.ini
Benefix of using ESP32 is that is faster, allows driving the V2 high resolution display and also supports compression. It's more precise to deepsleep long periods of time but it also consumes more. So it's up to you, depending on your project, what is the candidate to use as a display driver.

CALE project has been sponsored by makers store digitspace.com