Is it possible to connect more than 1 E-Ink display (IE: 7.3 impression and a 4" impression) using a breakout ribbon cable from the raspberry pi to each display?
I don’t have an answer to your direct question, but it looks like the Inky Impression 7.3 can be driven by a Zero as well as a regular Pi. So in the worst case your idea would be possible by pairing each screen with a separate Zero, and then connecting each Zero to a primary Pi that acts as a manager for the whole system.
There would be several ways to get the manager Pi to send display commands to the Zeros - BlueTooth is a possibility, but I’d probably just use WiFi.
I was afraid that might be the answer. I didn’t know if the displays were addressable or not (hence the one cable question). Thank you for your reply.
I don’t categorically know that it would be impossible to drive several displays with one device. One option you might have is to use a I2C or SPI breakout board that offers several connectors, and then see if you can find an e-ink display that runs off those wire protocols.
However, as I have discovered recently, not all displays have I2C/SPI drivers, even if theoretically they have that input. I myself am mulling trying to write a driver, after discovering that the display I want to use might need to be fed raw I2C commands rather than a higher-level pixel coordinate & colour commands. I might be mad to embark on such an undertaking, but it could be fun! 😛
Both e-inks use SPI and it is no problem to drive more than one device on a single SPI bus. Note that both devices use a 4-wire protocol, so you must reroute the DC and and CS pins of one display to some free pins and you also must convince the driver (which is the same for both displays) to use a different pair of pins than the standard ones for the second display. You must also check if the driver uses some global variables, in this case, you would also have to update the driver.
So in theory: yes, you can connect more than 1 e-ink to a pi (or any other host), but in practice, this could turn out difficult.