[Keyboard] Add support for jj4x4 numpad/macropad by Kprepublic (#5016)

* added keyboard jj4x4, a shorter version of the jj40

* removed useless file

* edited jj4x4 readme.md

* optimized array size in jj4x4 config.h, removed reference to jj40 layouts from rules.mk

* removed custom matrix for this ps2avrgb board, refactored column and row pins

1 files changed, 71 insertions, 0 deletions

diff --git a/keyboards/jj4x4/README.md b/keyboards/jj4x4/README.md
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+# jj4x4
+
+![jj4x4](https://cdn.shopify.com/s/files/1/2711/4238/products/JJ4x4case-1_1024x1024.jpg?v=1532325339)
+
+A  4x4 keypad kit made and KPRepublic on AliExpress. This is a chopped off version of the jj40 with rearranged keys.
+
+Keyboard Maintainer: [QMK Community](https://github.com/qmk)  
+Hardware Supported: Atmega32A  
+Hardware Availability: [AliExpress](https://www.aliexpress.com/item/jj4x4-jj4X4-16-keys-Custom-Mechanical-Keyboard-PCB-programmed-numpad-layouts-bface-firmware-with-rgb-bottom/32901955446.html?spm=2114.search0104.3.7.3ebf431ae1d9ic&ws_ab_test=searchweb0_0,searchweb201602_4_10065_10130_10068_10547_319_317_10548_10545_10696_453_10084_454_10083_433_10618_431_10307_537_536_10902_10059_10884_10887_321_322_10103,searchweb201603_6,ppcSwitch_0&algo_expid=9d1891dd-80af-4793-a889-5a62e1fdfdd8-1&algo_pvid=9d1891dd-80af-4793-a889-5a62e1fdfdd8&transAbTest=ae803_5)
+
+Make example for this keyboard (after setting up your build environment):
+
+    make jj4x4:default:program
+
+See [build environment setup](https://docs.qmk.fm/#/getting_started_build_tools) then the [make instructions](https://docs.qmk.fm/#/getting_started_make_guide) 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` ([GitHub repo](https://github.com/whiteneon/bootloadHID)) for flashing:
+
+For macOS:
+```
+$ brew cask install crosspack-avr
+$ brew install --HEAD https://raw.githubusercontent.com/robertgzr/homebrew-tap/master/bootloadhid.rb
+```
+
+For Linux:
+```
+$ sudo apt install libusb-dev
+$ wget https://www.obdev.at/downloads/vusb/bootloadHID.2012-12-08.tar.gz
+$ tar -xzf bootloadHID.2012-12-08.tar.gz
+$ cd bootloadHID.2012-12-08/commandline
+$ make
+$ sudo cp bootloadHID /usr/bin
+```
+
+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 (or are having issues with a `program` flash), you can just build it (`make jj40:<keymap-name>` and flash the firmware (`.hex` file) directly with
+`bootloadHID` if you boot the board while holding down `8` (second from top, second from left, with usb plug is at the top) to keep it
+in the bootloader:
+
+```
+$ make jj40
+$ bootloadHID -r jj4x4_default.hex
+```
+
+For Windows 10:
+Windows sometimes doesn't recognize the jj4x4. The easiest way of flashing a new layout is probably using [HIDBootFlash](http://vusb.wikidot.com/project:hidbootflash).
+1. Go to Windows Device Manager and find the keyboard (plug it in while holding down `8` (second from top, second from left, with usb plug is at the top)). It can be found under Human Interface Devices or under Keyboards.
+2. Go to properties and the Details tab to find the hardware ID. You want the VID and the PID (code after the underscore). Plug them into HIDBootFlash and hit Find Device.
+3. Use `make jj4x4:<keymap-name>` to generate the .hex file in the qmk basis folder. Select the .hex file in HIDBootFlash and press Flash Device.
+
+
+## Troubleshooting
+
+1. Try plugging the board in while pressing `8` (usb plug at top, second from top, second from left). 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.