RP Pico/Micropython remote keyboard

https://github.com/sarumpaet/MicropythonRemoteKeyboard

About

This is a poor man's KVM over IP. It is so poor that it misses the "V" and "M" (there's no video nor mouse support). On the upside, it doesn't only do IP but even Wifi! So call it K over Wifi if you want. Which perfectly describes it! Keyboard over Wifi.

Why, you ask?

There are other solutions that allow you to remote control a PC, including video transmission, mouse, etc., but those are a tad expensive and a bit of a hassle to set up.

Instead, this project assumes that you have remote hands, but also assumes that those hands have their hands full with connecting the remote keyboard hardware, and using some smartphone based video chat software for transmitting the screen contents to you.

You can even set up the USB stick (configuring network parameters is all that's necessary) and mail it in a small envelope.

Once plugged into the PC, the stick will...

1. connect to Wifi
2. TCP connect to an IP of your choice that runs the keyboard events emitter software
3. forward keyboard events received from the remote to the local PC as USB HID keyboard events.

You can even remote control the UEFI/BIOS this way.²

No VPN needed, no bulky KVM solution needed, total cost <10€.

Hardware

Install this on a "Pico W-2023" Raspberry Pi Pico clone. That hardware uses an RP2040 microcontroller combined with an ESP8285 running the ESP-AT firmware connected to the UART lines of the RP2040.

The Pico W-2023 often ships with the ESP-AT firmware not yet installed on the ESP. In that case, flash Serial_port_transmission.uf2 onto the RP2040 then reset with the ESP boot button pressed then flash the ESP with a 1MBit ESP-AT firmware.

It should be simple to port this to the real RP Pico W (that is using a CYW43 instead of an ESP for Wifi connectivity) as well. Porting to the ESP32-S line (that offers USB OTG) should also be possible, but MicroPython USB HID does not seem to support that yet.

Installation and Usage

1. Install MicroPython onto the Pico/RP2040.
2. Install mpremote on your PC.
3. mpremote mip install usb-device-keyboard
4. Install the remote keyboard into MicroPython: mpremote cp keyboard.py :main.py
5. Configure Wifi and server settings: mpremote edit main.py
6. Connect the stick to the PC you want to control
7. Launch the keyboard event server: python event_server.py
8. As long as the mouse is in the event server window, any keypresses are sent to the remote.

There are a few buttons in the software for common key combinations. The red button will send Magic SysRq to reboot.

The event server software must be reachable for TCP inbound connections originating from the stick. As an easy solution, you can configure the stick to connect to some host you control that has a public IP, then connect to that from the machine running the event server using ssh -R 0.0.0.0:PORT:127.0.0.1:PORT publichost or similar. sshd needs to have GatewayPorts yes set to allow binding other interfaces than localhost.

Troubleshooting

• Remote stick blinks 10 times: ESP could not get initialized (missing ESP-AT firmware or broken).
• Remote stick blinks 6 times: PC did not initialize stick as keyboard (power only cable?).
• Remote stick blinks 4 times: ESP could not connect to Wifi (wrong credentials?).
• Remote stick blinks 2 times: Could not connect to event server (server not yet started or missing connectivity).
• Remote stick blinks rapidly: All fine, connected to event server.

Caveats

• This is barely more than a proof of concept. You have been warned.
• There is no connection security/encryption. People might listen to any keypresses transmitted, or forge keypresses. Only connect the stick when needed, and don't enter passwords over the remote.
• ²There seems to be a minor bug in the MicroPython HID code - the keyboard endpoint seems to have protocol set to NONE by default so some BIOSes don't recognize the stick. Patch hid.py to fix.