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1. trm42+(OP)[view] [source] 2020-07-23 17:48:04
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.
replies(1): >>mtlync+Pf
2. mtlync+Pf[view] [source] 2020-07-23 19:06:30
>>trm42+(OP)
The 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/raspberry... [1] https://raspberrypi.stackexchange.com/questions/71613/how-to...

replies(2): >>Scaevo+Ej >>grutur+d31
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3. Scaevo+Ej[view] [source] [discussion] 2020-07-23 19:26:06
>>mtlync+Pf
I'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.
replies(1): >>mtlync+Lt
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4. mtlync+Lt[view] [source] [discussion] 2020-07-23 20:28:54
>>Scaevo+Ej
Yeah 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.
replies(1): >>Scaevo+l61
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5. grutur+d31[view] [source] [discussion] 2020-07-23 23:49:11
>>mtlync+Pf
Any 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.

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6. Scaevo+l61[view] [source] [discussion] 2020-07-24 00:16:43
>>mtlync+Lt
Woops, 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.
replies(1): >>mtlync+ti1
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7. mtlync+ti1[view] [source] [discussion] 2020-07-24 02:23:03
>>Scaevo+l61
The 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/

replies(1): >>magica+s04
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8. magica+s04[view] [source] [discussion] 2020-07-24 23:15:13
>>mtlync+ti1
On the web page you explicitly say to connect it to the port labelled "USB", which is not the power port.
replies(1): >>mtlync+1c4
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9. mtlync+1c4[view] [source] [discussion] 2020-07-25 01:34:20
>>magica+s04
Whoops, you're right. I misremembered. It's power on the Pi 4 and data on the Pi Zero.

Thanks for the correction!

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