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Thanks for reading! >Would a Pi Zero W work for this, or do you need a full-size Pi 4? I tested Key Mime Pi (the keyboard-only version) on the Pi Zero W and i
by mtlynch 6y ago
Thanks for reading!
>Would a Pi Zero W work for this, or do you need a full-size Pi 4?
I tested Key Mime Pi (the keyboard-only version) on the Pi Zero W and it worked great. I haven't tested TinyPilot on the Pi Zero W, but I think it will work. The video encoding is happening in the HDMI dongle, so it doesn't hammer resources much. I don't have a USB to microUSB adaptor on hand, but I'll order one now and see if it works.
>be able to package everything into a tiny 3D printed case.
Yeah, that would be neat! One of the biggest issues I have with TinyPilot's setup right now is that it looks kind of like a bunch of random hobbyist parts stuck together. A 3D printed case would be good and wouldn't have the heat issues that Pi 4 has.[0]
[0] https://www.jeffgeerling.com/blog/2019/best-way-keep-your-cool-running-raspberry-pi-4 https://www.jeffgeerling.com/blog/2019/best-way-keep-your-co...
- cricalix 6y agoYou might also be able to use the "standard" radio kit metal boxes - tap some standoffs, carefully drill some holes for wires etc. Dunno which works out better for the world - ordering a pre-fab metal box that you have to do some work on (or perhaps use https://www.frontpanelexpress.com/ https://www.frontpanelexpress.com/ to get a customised enclosure), or printing something from plastic. Might depend on production volume, metal used etc.
- trm42 6y agoDo you happen to have any idea, whether older RPIs like 1 or 2 could work for this fast enough? Have some of those laying around.
- mtlynch 6y agoThe video capture part should work, but I don't believe they support USB OTG, so they wouldn't be able to impersonate the keyboard. The official documentation[0] says all Pi devices have USB OTG, but I'm not sure if there's something else about the Pi 4 and Pi Zero W that allows USB gadget mode because I've never found anyone talking about using it before recent generations of Pi. This StackExchange answer says the A and the A+ had it, but that the 2 doesn't.[1] [0] https://www.raspberrypi.org/documentation/hardware/raspberrypi/usb/README.md#overview_pi4 https://www.raspberrypi.org/documentation/hardware/raspberry... [1] https://raspberrypi.stackexchange.com/questions/71613/how-to-use-raspberry-pi-3-as-a-usb-gadget/73911#73911 https://raspberrypi.stackexchange.com/questions/71613/how-to...
- Scaevolus 6y agoI'd expect the Pi Zero W to be fast enough to pass through the MJPEG stream and impersonate the keyboard, which should cut the cost by $20+ plus however much you save on not needing a fancy case.
- mtlynch 6y agoYeah that's true. I stopped thinking about the Pi Zero W early in the project because I assumed it would choke on video encoding. When I discovered that the HDMI dongle was doing the heavy lifting, I forgot to revisit that assumption. I'm going to order an USB to micro-USB adaptor to test it out because it would slim things down significantly.
- Scaevolus 6y agoWoops, forgot the major issue-- the Pi Zero only has one USB port (the other is just for power), so you couldn't get video frames in at the same time as you pretended to be a keyboard.
- mtlynch 6y agoThe Pi Zero's power port is actually a USB OTG port. I used it in my precursor project to forward keystrokes: https://mtlynch.io/key-mime-pi/ https://mtlynch.io/key-mime-pi/
- magicalhippo 6y agoOn the web page you explicitly say to connect it to the port labelled "USB", which is not the power port.
- mtlynch 6y agoWhoops, you're right. I misremembered. It's power on the Pi 4 and data on the Pi Zero. Thanks for the correction!