CH559 EasyUSBHost for HID Keyboards

A little HID keyboard -> UART adapter that translates keyboard inputs to ASCII texts. Lets you add keyboard inputs to your gadgets very easily.

What It Does

Translates HID keyboard inputs to ASCII texts and outputs via UART.
- Non-letter keys such as cursor keys are ignored (by default) or translated to VT100 (or xterm) control sequences.
- Caps lock and num lock are treated accordingly, including indicator LEDs on keyboard.
- Scroll lock key turns indicator LED on/off, but does not affect text output (by default).
- Shift and ctrl keys are treated accordingly. Alt and meta keys are ignored (by default).
Recognizes USB hubs and multiple keyboards. Maximum 16 USB devices (including hubs) and 8 keyboards.
- Inputs from multiple keyboards are merged into single output stream.
- Has a mode that prefixes address of the keyboard before ASCII value.
Barcode readers and other input devices are also recognized, as long as they are HID-keyboard compatible.

What It Doesn't Do

It doesn't translate extra utility keys (such as volume control and web launcher keys), as they are not part of generic HID keyboard protocol.

Features That May Be Useful

Supports JIS and US keyboard layouts.
Configurable key repeats.
Lock keys (caps, num, scroll) can be disabled individually.
- You can change lock states via UART or SPI, even if keys are disabled.
An open-collector pin that goes low when special key combination is pressed (default: ctrl + alt + del).
- Can be used to reset microcontroller or other external circuits.
Ctrl <-> capslock swapping.

Hardware Setup

Simply hook up CH559L as:

USB: HP and HM pins (pins 29 and 30) to a USB A receptacle.
UART1: RXD1 and TXD1 pins (pins 27 and 28) to a receiver (such as Arduino and other microcontrollers, anything you would like).
DP and DM pins (pins 31 and 32) are only used for downloading firmware.
Power pins to appropriate power, of course.

TBA: example schematic

This project is not tested on CH559T.

Compiling

You need SDCC and make to compile this project.

Additionally, this project uses --xstack option on SDCC. Since SDCC doesn't include libc libraries with --xstack option in its default install, you need to compile (and install) such libraries in order to compile this project. You can do so by doing make model-mcs51-xstack-auto in device/lib directory of the SDCC source.

Modify Makefile so that SDCC_PREFIX points to where your SDCC is installed in.

This project is intended to be compiled in WSL (Ubuntu).

License

GPL v3.

Credits

This project is derived (and extensively modified) from CH559sdccUSBHost

For my part:

CH559 EasyUSBHost for HID Keyboards Copyright (C) 2021 Kouichi Kuroi (q61.org)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

verylowfreq/CH559_EasyUSBHost