Added YMD75 support (#2968)

* Adding ymd75 files

* Added YMD75 support, inc layout json

* Added YMD75 support

1 files changed, 83 insertions, 0 deletions

diff --git a/keyboards/ymd75/README.md b/keyboards/ymd75/README.md
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+YMD75 / MT84
+==========================
+
+This is a port of the QMK firmware for boards that are based on the
+ps2avrGB firmware, like the [ps2avrGB keyboard] (https://www.keyclack.com/product/gb-ps2avrgb/), for use on the YMD75, from YMDK. YMDK sell the board and name it "YMD75", however the PCB has "MT84" printed on both sides.
+
+Most of the code was taken and amended from YMD96 and my port JJ50, which in itself was taken from ps2avrGB and amended by Andrew Novak.
+
+Note that this is a complete replacement for the firmware, so you won't be
+using Bootmapper Client to change any keyboard settings, since not all the
+USB report options are supported.  
+
+Hardware Supported: YMD75/MT84 with the ATmega32a chip.
+Hardware Availability: The YMD75/MT84 PCB is available from YMDK on AliExpress and suchlike.
+
+This version by Wayne K Jones (github.com/WarmCatUK)
+
+## Installing and Building
+
+Make example for this keyboard (after setting up your build environment):
+
+```
+$ make ymd75:default:program
+```
+It should detect the keyboard and set it to bootloader mode automatically, prior to flashing firmware.
+I've found that I need to remove the previous build/file before making a new one as it doesn't overwrite it; but this might just be my personal experience.
+
+See [build environment setup](https://docs.qmk.fm/build_environment_setup.html) then the [make instructions](https://docs.qmk.fm/make_instructions.html) for more information.
+
+Note that this is a complete replacement for the firmware, so you won't be
+using Bootmapper Client to change any keyboard settings, since not all the
+USB report options are supported.
+In addition you may need the AVR toolchain and `bootloadHID` for flashing:
+
+```
+$ brew cask install crosspack-avr
+$ brew install --HEAD https://raw.githubusercontent.com/robertgzr/homebrew-tap/master/bootloadhid.rb
+```
+
+In order to use the `./program` script, which can reboot the board into
+the bootloader, you'll need Python 2 with PyUSB installed:
+
+```
+$ pip install pyusb
+```
+
+If you prefer, you can just build it and flash the firmware directly with
+`bootloadHID` if you boot the board while holding down `Left Control` to keep it
+in the bootloader:
+
+```
+$ make ymd75
+$ bootloadHID -r ymd75_default.hex
+```
+I dont use windows personally, but the following is from ymd96 regarding flashing the atmega32a:
+
+Since the YMD75/MT84 uses an ATmega32a chip instead of the 32u4, you need to download [HIDBootFlash v.1.0](http://vusb.wikidot.com/project:hidbootflash) for Windows. If anyone knows of a Linux/Mac bootflasher that works, edit this readme!
+On Windows, I use [MINGw](http://www.mingw.org/) to compile the keymaps. On Linux or OSX you can simply use the terminal.
+
+Once you have those two pieces of software:
+Build the keyboard with  
+```
+$ make ymd75:default
+```  
+If you make your own layout, change the `default` word to whatever your layout is.  
+
+And flash the compiled hex file with `HIDBootFlash`. Simply put the board in flashing mode by plugging it in while holding the key below the top right key, and click `find device`. Then you can specify the .hex file and flash it to the device.
+
+
+## Troubleshooting
+
+1. Try plugging the board in while pressing `Backspace` (`Key below the top right key`). This will force it to boot only the bootloader without loading the firmware. Once this is done, just reflash the board with the original firmware.
+2. Sometimes USB hubs can act weird, so try connecting the board directly to your computer or plugging/unplugging the USB hub.
+3. If you get an error such as "Resource Unavailable" when attemting to flash on Linux, you may want to compile and run `tools/usb_detach.c`. See `tools/README.md` for more info.
+4. I was occasionally finding that I wasn't flashing changes that I was making to my keymap. If that happens, remove the previous build and simply force rebuild by making with:
+```
+$ rm ymd75_default.hex
+$ make -B ymd75:default
+$ make -B ymd75:default:program
+```
+
+
+