5 ms·
Do 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.
by trm42 6y ago
Do 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!
- deleted 6y ago[deleted]
- gruturo 6y agoAny Pi with just one USB port (zero, A, A+, 3A) is capable of USB gadget mode because there is no hub between the SOC and the port. Those with multiple ports have a hub in between and are not capable of gadget mode. The pi 4 is an exception, it is capable of gadget mode on its USB-C power input, not via the normal ports as there is a hub in between there too.