While listening to the latest MobileViews Podcast I heard Jon Westfall describe using the Raspberry Pi 4 as an accessory to an iPad Pro. The key component of the solution is the USB-C ports on the iPad Pro and the Raspberry Pi 4 because they are used to power the Raspberry Pi and provide network communication between the iPad and the Raspberry Pi. I am surprised that the iPad’s USB-C power output meets the Pi 4’s higher power input requirements, however I learned that the latest firmware upgrade for the Pi 4 includes a low power option along with Ethernet over USB, which are key for this working.
I’ve been using a Raspberry Pi Zero W in a similar manner except that I power it using USB battery and access it via WiFi when the Pi Zero is configured as a wireless access point. The result provides me access to Linux terminal apps but does not provide simultaneous access to the Internet.
I like the idea of using the Raspberry Pi 4 as described, but in my case I would need to buy a new iPad Pro with the USB-C port. Capabilities such of this do make the idea of upgrading to the latest iPad Pros more compelling.