[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

15 files changed, 1325 insertions, 0 deletions

diff --git a/keyboards/jj4x4/README.md b/keyboards/jj4x4/README.md
new file mode 100644
index 0000000000..09684bd825
--- /dev/null
+++ b/keyboards/jj4x4/README.md
@@ -0,0 +1,71 @@
+# 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.
diff --git a/keyboards/jj4x4/backlight.c b/keyboards/jj4x4/backlight.c
new file mode 100644
index 0000000000..fbd241fa9d
--- /dev/null
+++ b/keyboards/jj4x4/backlight.c
@@ -0,0 +1,213 @@
+/**
+ * Backlighting code for PS2AVRGB boards (ATMEGA32A)
+ * Kenneth A. (github.com/krusli | krusli.me)
+ */
+
+#include "backlight.h"
+#include "quantum.h"
+
+#include <avr/pgmspace.h>
+#include <avr/interrupt.h>
+
+#include "backlight_custom.h"
+#include "breathing_custom.h"
+
+// DEBUG
+#include <stdlib.h>
+#include <stdio.h>
+
+// Port D: digital pins of the AVR chipset
+#define NUMLOCK_PORT    (1 << 0)  // D0
+#define CAPSLOCK_PORT   (1 << 1)  // D1
+#define BACKLIGHT_PORT  (1 << 4)  // D4
+#define SCROLLLOCK_PORT (1 << 6)  // D6
+
+#define TIMER_CLK_DIV64			  0x03	///< Timer clocked at F_CPU/64
+#define TIMER1PRESCALE	TIMER_CLK_DIV64 ///< timer 1 prescaler default
+
+#define TIMER_PRESCALE_MASK		0x07	///< Timer Prescaler Bit-Mask
+
+#define PWM_MAX 0xFF
+#define TIMER_TOP 255 // 8 bit PWM
+
+extern backlight_config_t backlight_config;
+
+/**
+ * References
+ * Port Registers: https://www.arduino.cc/en/Reference/PortManipulation
+ * TCCR1A: https://electronics.stackexchange.com/questions/92350/what-is-the-difference-between-tccr1a-and-tccr1b
+ * Timers: http://www.avrbeginners.net/architecture/timers/timers.html
+ * 16-bit timer setup: http://sculland.com/ATmega168/Interrupts-And-Timers/16-Bit-Timer-Setup/
+ * PS2AVRGB firmware: https://github.com/showjean/ps2avrU/tree/master/firmware
+ */
+
+// @Override
+// turn LEDs on and off depending on USB caps/num/scroll lock states.
+__attribute__ ((weak))
+void led_set_user(uint8_t usb_led) {
+    if (usb_led & (1 << USB_LED_NUM_LOCK)) {
+      // turn on
+      DDRD  |= NUMLOCK_PORT;
+      PORTD |= NUMLOCK_PORT;
+    } else {
+      // turn off
+      DDRD  &= ~NUMLOCK_PORT;
+      PORTD &= ~NUMLOCK_PORT;
+    }
+
+    if (usb_led & (1 << USB_LED_CAPS_LOCK)) {
+      DDRD  |= CAPSLOCK_PORT;
+      PORTD |= CAPSLOCK_PORT;
+    } else {
+      DDRD  &= ~CAPSLOCK_PORT;
+      PORTD &= ~CAPSLOCK_PORT;
+    }
+
+    if (usb_led & (1 << USB_LED_SCROLL_LOCK)) {
+      DDRD  |= SCROLLLOCK_PORT;
+      PORTD |= SCROLLLOCK_PORT;
+    } else {
+      DDRD  &= ~SCROLLLOCK_PORT;
+      PORTD &= ~SCROLLLOCK_PORT;
+    }
+}
+
+#ifdef BACKLIGHT_ENABLE
+
+// sets up Timer 1 for 8-bit PWM
+void timer1PWMSetup(void) { // NOTE ONLY CALL THIS ONCE
+  // default 8 bit mode
+  TCCR1A &= ~(1 << 1); // cbi(TCCR1A,PWM11); <- set PWM11 bit to HIGH
+  TCCR1A |= (1 << 0);  // sbi(TCCR1A,PWM10); <- set PWM10 bit to LOW
+
+  // clear output compare value A
+  // outb(OCR1AH, 0);
+  // outb(OCR1AL, 0);
+
+  // clear output comparator registers for B
+	OCR1BH = 0; // outb(OCR1BH, 0);
+	OCR1BL = 0; // outb(OCR1BL, 0);
+}
+
+bool is_init = false;
+void timer1Init(void) {
+  // timer1SetPrescaler(TIMER1PRESCALE)
+  // set to DIV/64
+  (TCCR1B) = ((TCCR1B) & ~TIMER_PRESCALE_MASK) | TIMER1PRESCALE;
+
+  // reset TCNT1
+  TCNT1H = 0;  // outb(TCNT1H, 0);
+	TCNT1L = 0;  // outb(TCNT1L, 0);
+
+  // TOIE1: Timer Overflow Interrupt Enable (Timer 1);
+	TIMSK |= _BV(TOIE1); // sbi(TIMSK, TOIE1);
+
+  is_init = true;
+}
+
+void timer1UnInit(void) {
+  // set prescaler back to NONE
+  (TCCR1B) = ((TCCR1B) & ~TIMER_PRESCALE_MASK) | 0x00;  // TIMERRTC_CLK_STOP
+
+  // disable timer overflow interrupt
+  TIMSK &= ~_BV(TOIE1); // overflow bit?
+
+  setPWM(0);
+
+  is_init = false;
+}
+
+
+// handle TCNT1 overflow
+//! Interrupt handler for tcnt1 overflow interrupt
+ISR(TIMER1_OVF_vect, ISR_NOBLOCK)
+{
+	// sei();
+  // handle breathing here
+  #ifdef BACKLIGHT_BREATHING
+  if (is_breathing()) {
+    custom_breathing_handler();
+  }
+  #endif
+
+  // TODO call user defined function
+}
+
+// enable timer 1 PWM
+// timer1PWMBOn()
+void timer1PWMBEnable(void) {
+  // turn on channel B (OC1B) PWM output
+  // set OC1B as non-inverted PWM
+  TCCR1A |= _BV(COM1B1);
+  TCCR1A &= ~_BV(COM1B0);
+}
+
+// disable timer 1 PWM
+// timer1PWMBOff()
+void timer1PWMBDisable(void) {
+  TCCR1A &= ~_BV(COM1B1);
+  TCCR1A &= ~_BV(COM1B0);
+}
+
+void enableBacklight(void) {
+  DDRD  |= BACKLIGHT_PORT;  // set digital pin 4 as output
+  PORTD |= BACKLIGHT_PORT;  // set digital pin 4 to high
+}
+
+void disableBacklight(void) {
+  // DDRD  &= ~BACKLIGHT_PORT;  // set digital pin 4 as input
+  PORTD &= ~BACKLIGHT_PORT;  // set digital pin 4 to low
+}
+
+void startPWM(void) {
+  timer1Init();
+  timer1PWMBEnable();
+  enableBacklight();
+}
+
+void stopPWM(void) {
+  timer1UnInit();
+  disableBacklight();
+  timer1PWMBDisable();
+}
+
+void b_led_init_ports(void) {
+  /* turn backlight on/off depending on user preference */
+  #if BACKLIGHT_ON_STATE == 0
+    // DDRx register: sets the direction of Port D
+    // DDRD  &= ~BACKLIGHT_PORT;  // set digital pin 4 as input
+    PORTD &= ~BACKLIGHT_PORT;  // set digital pin 4 to low
+  #else
+    DDRD  |= BACKLIGHT_PORT;  // set digital pin 4 as output
+    PORTD |= BACKLIGHT_PORT;  // set digital pin 4 to high
+  #endif
+
+  timer1PWMSetup();
+  startPWM();
+
+  #ifdef BACKLIGHT_BREATHING
+  breathing_enable();
+  #endif
+}
+
+void b_led_set(uint8_t level) {
+  if (level > BACKLIGHT_LEVELS) {
+    level = BACKLIGHT_LEVELS;
+  }
+
+  setPWM((int)(TIMER_TOP * (float) level / BACKLIGHT_LEVELS));
+}
+
+// called every matrix scan
+void b_led_task(void) {
+  // do nothing for now
+}
+
+void setPWM(uint16_t xValue) {
+  if (xValue > TIMER_TOP) {
+    xValue = TIMER_TOP;
+  }
+  OCR1B = xValue; // timer1PWMBSet(xValue);
+}
+
+#endif  // BACKLIGHT_ENABLE
diff --git a/keyboards/jj4x4/backlight_custom.h b/keyboards/jj4x4/backlight_custom.h
new file mode 100644
index 0000000000..7210be840e
--- /dev/null
+++ b/keyboards/jj4x4/backlight_custom.h
@@ -0,0 +1,15 @@
+/**
+ * Backlighting code for PS2AVRGB boards (ATMEGA32A)
+ * Kenneth A. (github.com/krusli | krusli.me)
+ */
+
+#ifndef BACKLIGHT_CUSTOM_H
+#define BACKLIGHT_CUSTOM_H
+
+#include <avr/pgmspace.h>
+void b_led_init_ports(void);
+void b_led_set(uint8_t level);
+void b_led_task(void);
+void setPWM(uint16_t xValue);
+
+#endif  // BACKLIGHT_CUSTOM_H
diff --git a/keyboards/jj4x4/breathing_custom.h b/keyboards/jj4x4/breathing_custom.h
new file mode 100644
index 0000000000..71416b1b45
--- /dev/null
+++ b/keyboards/jj4x4/breathing_custom.h
@@ -0,0 +1,140 @@
+/**
+ * Breathing effect code for PS2AVRGB boards (ATMEGA32A)
+ * Works in conjunction with `backlight.c`.
+ *
+ * Code adapted from `quantum.c` to register with the existing TIMER1 overflow
+ * handler in `backlight.c` instead of setting up its own timer.
+ * Kenneth A. (github.com/krusli | krusli.me)
+ */
+
+#ifdef BACKLIGHT_ENABLE
+#ifdef BACKLIGHT_BREATHING
+
+#include "backlight_custom.h"
+
+#ifndef BREATHING_PERIOD
+#define BREATHING_PERIOD 6
+#endif
+
+#define breathing_min() do {breathing_counter = 0;} while (0)
+#define breathing_max() do {breathing_counter = breathing_period * 244 / 2;} while (0)
+
+// TODO make this share code with quantum.c
+
+#define BREATHING_NO_HALT  0
+#define BREATHING_HALT_OFF 1
+#define BREATHING_HALT_ON  2
+#define BREATHING_STEPS 128
+
+static uint8_t breathing_period = BREATHING_PERIOD;
+static uint8_t breathing_halt = BREATHING_NO_HALT;
+static uint16_t breathing_counter = 0;
+
+static bool breathing = false;
+
+bool is_breathing(void) {
+  return breathing;
+}
+
+// See http://jared.geek.nz/2013/feb/linear-led-pwm
+static uint16_t cie_lightness(uint16_t v) {
+  if (v <= 5243) // if below 8% of max
+    return v / 9; // same as dividing by 900%
+  else {
+    uint32_t y = (((uint32_t) v + 10486) << 8) / (10486 + 0xFFFFUL); // add 16% of max and compare
+    // to get a useful result with integer division, we shift left in the expression above
+    // and revert what we've done again after squaring.
+    y = y * y * y >> 8;
+    if (y > 0xFFFFUL) // prevent overflow
+      return 0xFFFFU;
+    else
+      return (uint16_t) y;
+  }
+}
+
+void breathing_enable(void) {
+  breathing = true;
+  breathing_counter = 0;
+  breathing_halt = BREATHING_NO_HALT;
+  // interrupt already registered
+}
+
+void breathing_pulse(void) {
+  if (get_backlight_level() == 0)
+    breathing_min();
+  else
+    breathing_max();
+  breathing_halt = BREATHING_HALT_ON;
+  // breathing_interrupt_enable();
+  breathing = true;
+}
+
+void breathing_disable(void) {
+  breathing = false;
+  // backlight_set(get_backlight_level());
+  b_led_set(get_backlight_level()); // custom implementation of backlight_set()
+}
+
+void breathing_self_disable(void)
+{
+  if (get_backlight_level() == 0)
+    breathing_halt = BREATHING_HALT_OFF;
+  else
+    breathing_halt = BREATHING_HALT_ON;
+}
+
+void breathing_toggle(void) {
+  if (is_breathing())
+    breathing_disable();
+  else
+    breathing_enable();
+}
+
+void breathing_period_set(uint8_t value)
+{
+  if (!value)
+    value = 1;
+  breathing_period = value;
+}
+
+void breathing_period_default(void) {
+  breathing_period_set(BREATHING_PERIOD);
+}
+
+void breathing_period_inc(void)
+{
+  breathing_period_set(breathing_period+1);
+}
+
+void breathing_period_dec(void)
+{
+  breathing_period_set(breathing_period-1);
+}
+
+/* To generate breathing curve in python:
+ * from math import sin, pi; [int(sin(x/128.0*pi)**4*255) for x in range(128)]
+ */
+static const uint8_t breathing_table[BREATHING_STEPS] PROGMEM = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 17, 20, 24, 28, 32, 36, 41, 46, 51, 57, 63, 70, 76, 83, 91, 98, 106, 113, 121, 129, 138, 146, 154, 162, 170, 178, 185, 193, 200, 207, 213, 220, 225, 231, 235, 240, 244, 247, 250, 252, 253, 254, 255, 254, 253, 252, 250, 247, 244, 240, 235, 231, 225, 220, 213, 207, 200, 193, 185, 178, 170, 162, 154, 146, 138, 129, 121, 113, 106, 98, 91, 83, 76, 70, 63, 57, 51, 46, 41, 36, 32, 28, 24, 20, 17, 15, 12, 10, 8, 6, 5, 4, 3, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
+
+// Use this before the cie_lightness function.
+static inline uint16_t scale_backlight(uint16_t v) {
+  return v / BACKLIGHT_LEVELS * get_backlight_level();
+}
+
+void custom_breathing_handler(void) {
+  uint16_t interval = (uint16_t) breathing_period * 244 / BREATHING_STEPS;
+  // resetting after one period to prevent ugly reset at overflow.
+  breathing_counter = (breathing_counter + 1) % (breathing_period * 244);
+  uint8_t index = breathing_counter / interval % BREATHING_STEPS;
+
+  if (((breathing_halt == BREATHING_HALT_ON) && (index == BREATHING_STEPS / 2)) ||
+      ((breathing_halt == BREATHING_HALT_OFF) && (index == BREATHING_STEPS - 1)))
+  {
+      // breathing_interrupt_disable();
+  }
+
+  setPWM(cie_lightness(scale_backlight((uint16_t) pgm_read_byte(&breathing_table[index]) * 0x0101U)));
+}
+
+#endif // BACKLIGHT_BREATHING
+#endif  // BACKLIGHT_ENABLE
diff --git a/keyboards/jj4x4/config.h b/keyboards/jj4x4/config.h
new file mode 100644
index 0000000000..d48df5f1db
--- /dev/null
+++ b/keyboards/jj4x4/config.h
@@ -0,0 +1,53 @@
+/*
+Copyright 2017 Luiz Ribeiro <luizribeiro@gmail.com>
+
+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 2 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 <http://www.gnu.org/licenses/>.
+*/
+
+#include "config_common.h"
+
+#ifndef CONFIG_H
+#define CONFIG_H
+
+#define VENDOR_ID       0x20A0
+#define PRODUCT_ID      0x422D
+// TODO: share these strings with usbconfig.h
+// Edit usbconfig.h to change these.
+#define MANUFACTURER    Kprepublic
+#define PRODUCT         jj4x4
+
+/* matrix size */
+#define MATRIX_ROWS 4
+#define MATRIX_COLS 4
+#define MATRIX_ROW_PINS { B5, B0, B3, B4 }
+#define MATRIX_COL_PINS { A1, A0, A2, A3 }
+
+/* COL2ROW or ROW2COL */
+#define DIODE_DIRECTION COL2ROW
+
+#define BACKLIGHT_LEVELS 12
+// #define BACKLIGHT_BREATHING  // works, but BL_TOGG might not work
+
+#define TAPPING_TOGGLE 3
+
+#define NO_UART 1
+
+/* RGB underglow */
+// The RGB_DI_PIN value seems to be shared between all PS2AVRGB boards.
+// The same pin is used on the JJ40, at least.
+#define RGBLED_NUM 5
+#define RGB_DI_PIN E2 // NOTE: for PS2AVRGB boards, underglow commands are sent via I2C to 0xB0.
+#define RGBLIGHT_ANIMATIONS
+
+#endif
diff --git a/keyboards/jj4x4/i2c.c b/keyboards/jj4x4/i2c.c
new file mode 100644
index 0000000000..c27f3e3d17
--- /dev/null
+++ b/keyboards/jj4x4/i2c.c
@@ -0,0 +1,104 @@
+/*
+Copyright 2016 Luiz Ribeiro <luizribeiro@gmail.com>
+
+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 2 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 <http://www.gnu.org/licenses/>.
+*/
+
+#include <avr/io.h>
+#include <util/twi.h>
+
+#include "i2c.h"
+
+void i2c_set_bitrate(uint16_t bitrate_khz) {
+    uint8_t bitrate_div = ((F_CPU / 1000l) / bitrate_khz);
+    if (bitrate_div >= 16) {
+        bitrate_div = (bitrate_div - 16) / 2;
+    }
+    TWBR = bitrate_div;
+}
+
+void i2c_init(void) {
+    // set pull-up resistors on I2C bus pins
+    PORTC |= 0b11;
+
+    i2c_set_bitrate(400);
+
+    // enable TWI (two-wire interface)
+    TWCR |= (1 << TWEN);
+
+    // enable TWI interrupt and slave address ACK
+    TWCR |= (1 << TWIE);
+    TWCR |= (1 << TWEA);
+}
+
+uint8_t i2c_start(uint8_t address) {
+    // reset TWI control register
+    TWCR = 0;
+
+    // begin transmission and wait for it to end
+    TWCR = (1<<TWINT) | (1<<TWSTA) | (1<<TWEN);
+    while (!(TWCR & (1<<TWINT)));
+
+    // check if the start condition was successfully transmitted
+    if ((TWSR & 0xF8) != TW_START) {
+        return 1;
+    }
+
+    // transmit address and wait
+    TWDR = address;
+    TWCR = (1<<TWINT) | (1<<TWEN);
+    while (!(TWCR & (1<<TWINT)));
+
+    // check if the device has acknowledged the READ / WRITE mode
+    uint8_t twst = TW_STATUS & 0xF8;
+    if ((twst != TW_MT_SLA_ACK) && (twst != TW_MR_SLA_ACK)) {
+        return 1;
+    }
+
+    return 0;
+}
+
+void i2c_stop(void) {
+    TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);
+}
+
+uint8_t i2c_write(uint8_t data) {
+    TWDR = data;
+
+    // transmit data and wait
+    TWCR = (1<<TWINT) | (1<<TWEN);
+    while (!(TWCR & (1<<TWINT)));
+
+    if ((TWSR & 0xF8) != TW_MT_DATA_ACK) {
+        return 1;
+    }
+
+    return 0;
+}
+
+uint8_t i2c_send(uint8_t address, uint8_t *data, uint16_t length) {
+    if (i2c_start(address)) {
+        return 1;
+    }
+
+    for (uint16_t i = 0; i < length; i++) {
+        if (i2c_write(data[i])) {
+            return 1;
+        }
+    }
+
+    i2c_stop();
+
+    return 0;
+}
diff --git a/keyboards/jj4x4/i2c.h b/keyboards/jj4x4/i2c.h
new file mode 100644
index 0000000000..27c9d3d050
--- /dev/null
+++ b/keyboards/jj4x4/i2c.h
@@ -0,0 +1,25 @@
+/*
+Copyright 2016 Luiz Ribeiro <luizribeiro@gmail.com>
+
+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 2 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 <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __I2C_H__
+#define __I2C_H__
+
+void i2c_init(void);
+void i2c_set_bitrate(uint16_t bitrate_khz);
+uint8_t i2c_send(uint8_t address, uint8_t *data, uint16_t length);
+
+#endif
diff --git a/keyboards/jj4x4/info.json b/keyboards/jj4x4/info.json
new file mode 100644
index 0000000000..c6416ce168
--- /dev/null
+++ b/keyboards/jj4x4/info.json
@@ -0,0 +1,23 @@
+{
+  "keyboard_name": "jj40",
+  "url": "",
+  "maintainer": "qmk",
+  "width": 12,
+  "height": 4,
+  "layouts": {
+    "LAYOUT_planck_mit": {
+      "key_count": 47,
+      "layout": [{"x":0, "y":0}, {"x":1, "y":0}, {"x":2, "y":0}, {"x":3, "y":0}, {"x":4, "y":0}, {"x":5, "y":0}, {"x":6, "y":0}, {"x":7, "y":0}, {"x":8, "y":0}, {"x":9, "y":0}, {"x":10, "y":0}, {"x":11, "y":0}, {"x":0, "y":1}, {"x":1, "y":1}, {"x":2, "y":1}, {"x":3, "y":1}, {"x":4, "y":1}, {"x":5, "y":1}, {"x":6, "y":1}, {"x":7, "y":1}, {"x":8, "y":1}, {"x":9, "y":1}, {"x":10, "y":1}, {"x":11, "y":1}, {"x":0, "y":2}, {"x":1, "y":2}, {"x":2, "y":2}, {"x":3, "y":2}, {"x":4, "y":2}, {"x":5, "y":2}, {"x":6, "y":2}, {"x":7, "y":2}, {"x":8, "y":2}, {"x":9, "y":2}, {"x":10, "y":2}, {"x":11, "y":2}, {"x":0, "y":3}, {"x":1, "y":3}, {"x":2, "y":3}, {"x":3, "y":3}, {"x":4, "y":3}, {"x":5, "y":3, "w":2}, {"x":7, "y":3}, {"x":8, "y":3}, {"x":9, "y":3}, {"x":10, "y":3}, {"x":11, "y":3}]
+    },
+
+    "LAYOUT_ortho_4x12": {
+      "key_count": 48,
+      "layout": [{"x":0, "y":0}, {"x":1, "y":0}, {"x":2, "y":0}, {"x":3, "y":0}, {"x":4, "y":0}, {"x":5, "y":0}, {"x":6, "y":0}, {"x":7, "y":0}, {"x":8, "y":0}, {"x":9, "y":0}, {"x":10, "y":0}, {"x":11, "y":0}, {"x":0, "y":1}, {"x":1, "y":1}, {"x":2, "y":1}, {"x":3, "y":1}, {"x":4, "y":1}, {"x":5, "y":1}, {"x":6, "y":1}, {"x":7, "y":1}, {"x":8, "y":1}, {"x":9, "y":1}, {"x":10, "y":1}, {"x":11, "y":1}, {"x":0, "y":2}, {"x":1, "y":2}, {"x":2, "y":2}, {"x":3, "y":2}, {"x":4, "y":2}, {"x":5, "y":2}, {"x":6, "y":2}, {"x":7, "y":2}, {"x":8, "y":2}, {"x":9, "y":2}, {"x":10, "y":2}, {"x":11, "y":2}, {"x":0, "y":3}, {"x":1, "y":3}, {"x":2, "y":3}, {"x":3, "y":3}, {"x":4, "y":3}, {"x":5, "y":3}, {"x":6, "y":3}, {"x":7, "y":3}, {"x":8, "y":3}, {"x":9, "y":3}, {"x":10, "y":3}, {"x":11, "y":3}]
+    },
+
+    "LAYOUT_planck_1x2uR": {
+      "key_count": 47,
+      "layout": [{"x":0, "y":0}, {"x":1, "y":0}, {"x":2, "y":0}, {"x":3, "y":0}, {"x":4, "y":0}, {"x":5, "y":0}, {"x":6, "y":0}, {"x":7, "y":0}, {"x":8, "y":0}, {"x":9, "y":0}, {"x":10, "y":0}, {"x":11, "y":0}, {"x":0, "y":1}, {"x":1, "y":1}, {"x":2, "y":1}, {"x":3, "y":1}, {"x":4, "y":1}, {"x":5, "y":1}, {"x":6, "y":1}, {"x":7, "y":1}, {"x":8, "y":1}, {"x":9, "y":1}, {"x":10, "y":1}, {"x":11, "y":1}, {"x":0, "y":2}, {"x":1, "y":2}, {"x":2, "y":2}, {"x":3, "y":2}, {"x":4, "y":2}, {"x":5, "y":2}, {"x":6, "y":2}, {"x":7, "y":2}, {"x":8, "y":2}, {"x":9, "y":2}, {"x":10, "y":2}, {"x":11, "y":2}, {"x":0, "y":3}, {"x":1, "y":3}, {"x":2, "y":3}, {"x":3, "y":3}, {"x":4, "y":3}, {"x":5, "y":3}, {"x":6, "y":3, "w":2}, {"x":8, "y":3}, {"x":9, "y":3}, {"x":10, "y":3}, {"x":11, "y":3}]
+    }
+  }
+}
diff --git a/keyboards/jj4x4/jj4x4.c b/keyboards/jj4x4/jj4x4.c
new file mode 100644
index 0000000000..6fbff7afba
--- /dev/null
+++ b/keyboards/jj4x4/jj4x4.c
@@ -0,0 +1,97 @@
+/*
+Copyright 2017 Luiz Ribeiro <luizribeiro@gmail.com>
+Modified 2018 Kenneth A. <github.com/krusli>
+
+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 2 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 <http://www.gnu.org/licenses/>.
+*/
+
+#include "jj4x4.h"
+
+#include <avr/pgmspace.h>
+
+#include "action_layer.h"
+#include "quantum.h"
+
+#include "i2c.h"
+
+#include "backlight.h"
+#include "backlight_custom.h"
+
+// for keyboard subdirectory level init functions
+// @Override
+void matrix_init_kb(void) {
+  // call user level keymaps, if any
+  matrix_init_user();
+}
+
+#ifdef BACKLIGHT_ENABLE
+/// Overrides functions in `quantum.c`
+void backlight_init_ports(void) {
+  b_led_init_ports();
+}
+
+void backlight_task(void) {
+  b_led_task();
+}
+
+void backlight_set(uint8_t level) {
+  b_led_set(level);
+}
+#endif
+
+#ifdef RGBLIGHT_ENABLE
+extern rgblight_config_t rgblight_config;
+
+// custom RGB driver
+void rgblight_set(void) {
+  if (!rgblight_config.enable) {
+    for (uint8_t i=0; i<RGBLED_NUM; i++) {
+      led[i].r = 0;
+      led[i].g = 0;
+      led[i].b = 0;
+    }
+  }
+
+  i2c_init();
+  i2c_send(0xb0, (uint8_t*)led, 3 * RGBLED_NUM);
+}
+
+bool rgb_init = false;
+
+void matrix_scan_kb(void) {
+  // if LEDs were previously on before poweroff, turn them back on
+  if (rgb_init == false && rgblight_config.enable) {
+    i2c_init();
+    i2c_send(0xb0, (uint8_t*)led, 3 * RGBLED_NUM);
+    rgb_init = true;
+  }
+
+  rgblight_task();
+#else
+void matrix_scan_kb(void) {
+#endif
+  matrix_scan_user();
+  /* Nothing else for now. */
+}
+
+__attribute__((weak)) // overridable
+void matrix_init_user(void) {
+
+}
+
+
+__attribute__((weak)) // overridable
+void matrix_scan_user(void) {
+
+}
diff --git a/keyboards/jj4x4/jj4x4.h b/keyboards/jj4x4/jj4x4.h
new file mode 100644
index 0000000000..03cf5d8a62
--- /dev/null
+++ b/keyboards/jj4x4/jj4x4.h
@@ -0,0 +1,46 @@
+/*
+Copyright 2017 Luiz Ribeiro <luizribeiro@gmail.com>
+
+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 2 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 <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef KEYMAP_COMMON_H
+#define KEYMAP_COMMON_H
+
+#include "quantum.h"
+#include "quantum_keycodes.h"
+#include "keycode.h"
+#include "action.h"
+
+void matrix_init_user(void);  // TODO port this to other PS2AVRGB boards
+
+#define XXX KC_NO
+
+	
+#define LAYOUT( \
+	K01, K02, K03, K04, \
+	K11, K12, K13, K14, \
+	K21, K22, K23, K24, \
+	K31, K32, K33, K34 \
+) \
+{ \
+  { K01, K02, K03, K04 }, \
+  { K11, K12, K13, K14 }, \
+  { K21, K22, K23, K24 }, \
+  { K31, K32, K33, K34 } \
+}	
+
+
+
+#endif
diff --git a/keyboards/jj4x4/keymaps/default/keymap.c b/keyboards/jj4x4/keymaps/default/keymap.c
new file mode 100644
index 0000000000..d4130e8090
--- /dev/null
+++ b/keyboards/jj4x4/keymaps/default/keymap.c
@@ -0,0 +1,34 @@
+#include QMK_KEYBOARD_H
+
+
+#define _QWERTY 0
+
+
+enum custom_keycodes {
+  QWERTY = SAFE_RANGE,
+};
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+/* Qwerty
+ * ,---------------------------.
+ * |   A  |   B  |   C  |  D   |
+ * +------+------+------+------|
+ * |   E  |   F  |   G  |  H   |
+ * +------+------+------+------|
+ * |   I  |   J  |   K  |  L   |
+ * +------+------+------+------|
+ * |   M  |   N  |   O  |  P   |
+ * ----------------------------'
+ */
+[_QWERTY] = LAYOUT( \
+  KC_A,    KC_B,    KC_C,   KC_D, \
+  KC_E,    KC_F,    KC_G,   KC_H, \
+  KC_I,    KC_J,    KC_K,   KC_L, \
+  KC_M,    KC_N,    KC_O,   KC_P  \
+),
+};
+
+// Loop
+void matrix_scan_user(void) {
+  // Empty
+};
diff --git a/keyboards/jj4x4/rules.mk b/keyboards/jj4x4/rules.mk
new file mode 100644
index 0000000000..3e222c620d
--- /dev/null
+++ b/keyboards/jj4x4/rules.mk
@@ -0,0 +1,58 @@
+# Copyright 2017 Luiz Ribeiro <luizribeiro@gmail.com>
+#
+# 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 2 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 <http://www.gnu.org/licenses/>.
+
+# MCU name
+MCU = atmega32a
+PROTOCOL = VUSB
+
+# unsupported features for now
+NO_UART = yes
+NO_SUSPEND_POWER_DOWN = yes
+
+# processor frequency
+F_CPU = 12000000
+
+# Bootloader
+#     This definition is optional, and if your keyboard supports multiple bootloaders of
+#     different sizes, comment this out, and the correct address will be loaded
+#     automatically (+60). See bootloader.mk for all options.
+BOOTLOADER = bootloadHID
+
+# build options
+BOOTMAGIC_ENABLE = no
+MOUSEKEY_ENABLE = no
+EXTRAKEY_ENABLE = yes
+CONSOLE_ENABLE = no
+COMMAND_ENABLE = yes
+
+BACKLIGHT_ENABLE = yes
+BACKLIGHT_CUSTOM_DRIVER = yes
+
+RGBLIGHT_ENABLE = yes
+RGBLIGHT_CUSTOM_DRIVER = yes
+
+KEY_LOCK_ENABLE = yes
+
+# Do not enable SLEEP_LED_ENABLE. it uses the same timer as BACKLIGHT_ENABLE
+SLEEP_LED_ENABLE = no    # Breathing sleep LED during USB suspend
+
+OPT_DEFS = -DDEBUG_LEVEL=0
+
+SRC = i2c.c backlight.c
+
+# programming options
+PROGRAM_CMD = ./util/atmega32a_program.py $(TARGET).hex
+
+
diff --git a/keyboards/jj4x4/tools/README.md b/keyboards/jj4x4/tools/README.md
new file mode 100644
index 0000000000..081984ed44
--- /dev/null
+++ b/keyboards/jj4x4/tools/README.md
@@ -0,0 +1,16 @@
+# JJ40 Tools
+
+## usb_detach.c
+
+When trying to flash on Linux, you may encounter a "Resource Unavailable" error. This means that Linux's HID driver has taken exclusive control of the keyboard, and the program script can't flash it.
+This program can force Linux to give up a device, so that the programming script can reset it.
+
+### To compile:
+```
+gcc usb_detach.c -o usb_detach
+```
+
+### To run:
+1. Use `lsusb` to discover the Bus and Device numbers for your keyboard.
+2. Run the program: `sudo ./usb_detach /dev/bus/usb/<BUS>/<DEVICE>`.
+3. Build and program the firmware as normal.
diff --git a/keyboards/jj4x4/tools/usb_detach.c b/keyboards/jj4x4/tools/usb_detach.c
new file mode 100644
index 0000000000..c21e47a7a4
--- /dev/null
+++ b/keyboards/jj4x4/tools/usb_detach.c
@@ -0,0 +1,33 @@
+/* Found at https://www.linuxquestions.org/questions/linux-hardware-18/how-to-unclaim-usb-device-558138/#post3406986 */
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <linux/ioctl.h>
+#include <linux/usbdevice_fs.h>