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Comment by walterbell | Hacker News Reader

Linux on Pi Zero can be used as a sidecar for iPads.

https://schwarztech.net/articles/my-ipads-raspberry-pi-sidec...

  This method configures the Raspberry Pi [Zero] in “gadget” mode, creating a private link that appears as a wired Ethernet connection over a USB cable. The Pi’s address will never change, either as it is also a DHCP server for the iPad. As an added bonus, the same cable powers the Pi, creating a setup as simple as plugging the Pi into your iPad and waiting for it to appear .. you have a full-blown Linux computer working in tandem with your iPad and the iPad acting as a directly-connected console that is also providing power.

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The Pi Zero is a full SoC which naturally runs Linux. Any Linux SoC with USB (so basically all of them) could use used in the same way.

This article is about the RP2350's microcontroller cores. It doesn't even have an MMU, so running Linux on it is much more interesting. It's not as capable as the normal Linux we run on bigger boards, but it's still interesting.

Could Linux on RP2350 cores work with iPad via Pi Zero form factor, with microSD storage to supplement iPad?

https://www.cnx-software.com/2025/07/08/rp2350-pizero-rp2350...

On aliexpress, there’s Pi Pico Dev dev boards featuring the RP2350 in the Pi Zero form factor.

https://www.aliexpress.us/item/3256807163052616.html

Thanks for the pointer!

Any non RP2xxx pi can be used like that. Unrelated to this post at all? I only fall back to that when there is no interwebs, otherwise connecting over ssh to a normal server is far more productive.

Those are larger. RP2350 1.5" iPad sidecar with microSD = 90% discount on Apple storage, https://news.ycombinator.com/item?id=46562471

Can you provide an example of rp2350 being useful as a sidecar outside of context being a dev board with GPIO?

I used sidecar to run my portable dev env, so I can write and compile code while I'm traveling. Ultimately, I changed this setup to have NUC-ish machine with me that plugs into a wall and normal Ethernet cable to connect to iPad because even RPi 5 is too slow for anything I do. I don't see linked rp2350 being useful at all.

Discount on what storage? Apple doesn't deal in microSD cards on iPads. There are much easier ways to get microSD or even NVMe on iPad than a linux sidecar.

I used to do the same thing with a full RPi4. I’m pretty sure that was the first non-pi zero that worked in gadget mode.

I was trying to make an attached Linux machine for my iPad instead of using a cloud VM. It was pretty effective, but at the time the ARM distributions were difficult to run what I wanted. Now, however, it would be significantly better.

Going in the other direction: recent Intel laptops with Thunderbolt should support USB gadget mode. In theory, this would allow a Linux laptop to emulate keyboard and mouse input to an iPad Mini portrait sidecar, with seamless kb/mouse context switching onto USB, as the cursor moved into the configured virtual viewport of the iPad "monitor".

Similar to synergy/barrier/input-leap, but using USB gadget mode instead of local network, since iOS wouldn't allow installation of non-Apple keyboard-mouse remoting software, https://github.com/input-leap/input-leap

I'm doing it with Bluetooth.

Gave up fairly quickly on using linux bt stack as it's... Not fun.

Instead I have a ESP32 dongle style board [0] connected with usb to my computer, it present itself as BT HID device to the iPad and communicate with the computer via serial.

Still wip, but overall it works for my main use case(skipping songs & managing volume).

[0] https://www.waveshare.com/esp32-s3-lcd-1.47.htm

I carry around an pwnagotchi[1], it serves not only as a cute little paper display, but also a battery powered Linux box.

Can do everything you wanna do, in a cute little box attached to a backpack.

My battery lasts about 3 hours, but its easy to juice it up if we go hiking and need a common filesystem up some mountain somewhere, know what I’m saying ..

(PS - the pwnatotchi part is just an app you can disable if you just want your Linux box to be a Linux box, but it sure is a fun little toy also ..)

[1] - https://www.thingiverse.com/search?q=pwnagotchi

Thanks for linking this, I would not have expected this usage (more from the iPad side being locked down) and it has inspired some thought.

It can be used to mirror content for offline viewing, e.g. share sheet sends URL to iOS shortcut, which uses SSH to send yt-dlp or wget archive command line to Linux sidecar, which has microSD storage (more capacity, lower cost/GB). Linux can host WebDAV/CalDAV and SFTP content for iPad apps and media players.

Cool, but any SBC that runs Linux and has a USB port that supports gadget mode can do this. Either way, what does this have to do with the article?

Most SBCs are larger. I was looking for the smallest iPad Linux sidecar, when I submitted this article. Here is one with RP2350, 1.5" display, USB-c and microSD, https://www.waveshare.com/rp2350-lcd-1.47-a.htm. Apple sold over 600 million iPads. Some of those could benefit from Linux sidecars to add functionality not available on iPadOS, increasing demand for small RP2350 boards.

This is a really good way to side step certain kinds of Apple MFI. "I'm not a custom super widget?! I'm an ethernet adapter!!"

Gotta get Pi Zero 2, way stronger hardware

side note: I wish it had more ram so you could mount it in VS Code vs. developing through SSH

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