Adds IS31FL3731 RGB Matrix Implementation (#2910)

* adds is31fl3731 rgb matrix implementation

* fix build script for force pushes

* allow bootloader size to be overwritten

* adds planck light implementation

* split led config into 2 arrays

* idk

* betterize register handling

* update planck implementation

* update planck

* refine rgb interface

* cleanup names, rgb matrix

* start documentation

* finish up docs

* add effects list

* clean-up merge

* add RGB_MATRIX_SKIP_FRAMES

* add support for at90usb1286 to bootloader options

19 files changed, 2336 insertions, 19 deletions

diff --git a/bootloader.mk b/bootloader.mk
index 55352f3d42..f30e38dd05 100644
--- a/bootloader.mk
+++ b/bootloader.mk
@@ -32,17 +32,32 @@
 ifeq ($(strip $(BOOTLOADER)), atmel-dfu)
     OPT_DEFS += -DBOOTLOADER_ATMEL_DFU
     OPT_DEFS += -DBOOTLOADER_DFU
-    BOOTLOADER_SIZE = 4096
+    ifeq ($(strip $(MCU)), atmega32u4)
+      BOOTLOADER_SIZE = 4096
+    endif
+    ifeq ($(strip $(MCU)), at90usb1286)
+      BOOTLOADER_SIZE = 8192
+    endif
 endif
 ifeq ($(strip $(BOOTLOADER)), lufa-dfu)
     OPT_DEFS += -DBOOTLOADER_LUFA_DFU
     OPT_DEFS += -DBOOTLOADER_DFU
-    BOOTLOADER_SIZE = 4096
+    ifeq ($(strip $(MCU)), atmega32u4)
+      BOOTLOADER_SIZE = 4096
+    endif
+    ifeq ($(strip $(MCU)), at90usb1286)
+      BOOTLOADER_SIZE = 8192
+    endif
 endif
 ifeq ($(strip $(BOOTLOADER)), qmk-dfu)
     OPT_DEFS += -DBOOTLOADER_QMK_DFU
     OPT_DEFS += -DBOOTLOADER_DFU
-    BOOTLOADER_SIZE = 4096
+    ifeq ($(strip $(MCU)), atmega32u4)
+      BOOTLOADER_SIZE = 4096
+    endif
+    ifeq ($(strip $(MCU)), at90usb1286)
+      BOOTLOADER_SIZE = 8192
+    endif
 endif
 ifeq ($(strip $(BOOTLOADER)), halfkay)
     OPT_DEFS += -DBOOTLOADER_HALFKAY
@@ -59,4 +74,4 @@ endif
 
 ifdef BOOTLOADER_SIZE
     OPT_DEFS += -DBOOTLOADER_SIZE=$(strip $(BOOTLOADER_SIZE))
-endif
\ No newline at end of file
+endif
diff --git a/common_features.mk b/common_features.mk
index 7bd43afdba..7ba7d48154 100644
--- a/common_features.mk
+++ b/common_features.mk
@@ -114,6 +114,15 @@ ifeq ($(strip $(RGBLIGHT_ENABLE)), yes)
     endif
 endif
 
+ifeq ($(strip $(RGB_MATRIX_ENABLE)), yes)
+    OPT_DEFS += -DRGB_MATRIX_ENABLE
+    SRC += is31fl3731.c
+    SRC += TWIlib.c
+    SRC += $(QUANTUM_DIR)/color.c
+    SRC += $(QUANTUM_DIR)/rgb_matrix.c
+    CIE1931_CURVE = yes
+endif
+
 ifeq ($(strip $(TAP_DANCE_ENABLE)), yes)
     OPT_DEFS += -DTAP_DANCE_ENABLE
     SRC += $(QUANTUM_DIR)/process_keycode/process_tap_dance.c
diff --git a/docs/feature_rgb_matrix.md b/docs/feature_rgb_matrix.md
new file mode 100644
index 0000000000..dfc103247a
--- /dev/null
+++ b/docs/feature_rgb_matrix.md
@@ -0,0 +1,141 @@
+# RGB Matrix Lighting
+
+There is basic support for addressable RGB matrix lighting with the I2C IS31FL3731 RGB controller. To enable it, add this to your `rules.mk`:
+
+    RGB_MATRIX_ENABLE = yes
+
+Configure the hardware via your `config.h`:
+
+	// This is a 7-bit address, that gets left-shifted and bit 0
+	// set to 0 for write, 1 for read (as per I2C protocol)
+	// The address will vary depending on your wiring:
+	// 0b1110100 AD <-> GND
+	// 0b1110111 AD <-> VCC
+	// 0b1110101 AD <-> SCL
+	// 0b1110110 AD <-> SDA
+	#define DRIVER_ADDR_1 0b1110100
+	#define DRIVER_ADDR_2 0b1110110
+
+	#define DRIVER_COUNT 2
+	#define DRIVER_1_LED_TOTAL 25
+	#define DRIVER_2_LED_TOTAL 24
+	#define DRIVER_LED_TOTAL DRIVER_1_LED_TOTAL + DRIVER_2_LED_TOTAL
+
+Currently only 2 drivers are supported, but it would be trivial to support all 4 combinations.
+
+Define these arrays listing all the LEDs in your `<keyboard>.c`:
+
+	const is31_led g_is31_leds[DRIVER_LED_TOTAL] = {
+	/* Refer to IS31 manual for these locations
+	 *   driver
+	 *   |  R location
+	 *   |  |      G location
+	 *   |  |      |      B location
+	 *   |  |      |      | */
+	    {0, C1_3,  C2_3,  C3_3},
+	    ....
+	}
+
+Where `Cx_y` is the location of the LED in the matrix defined by [the datasheet](http://www.issi.com/WW/pdf/31FL3731.pdf). The `driver` is the index of the driver you defined in your `config.h` (`0` or `1` right now).
+
+	const rgb_led g_rgb_leds[DRIVER_LED_TOTAL] = {
+	/* {row | col << 4}
+	 *    |           {x=0..224, y=0..64}
+	 *    |              |               modifier
+	 *    |              |                 | */
+	    {{0|(0<<4)},   {20.36*0, 21.33*0}, 1},
+	    {{0|(1<<4)},   {20.36*1, 21.33*0}, 1},
+	    ....
+	}
+
+The format for the matrix position used in this array is `{row | (col << 4)}`. The `x` is between (inclusive) 0-224, and `y` is between (inclusive) 0-64. The easiest way to calculate these positions is:
+
+    x = 224 / ( NUMBER_OF_ROWS - 1 ) * ROW_POSITION
+    y = 64 / (NUMBER_OF_COLS - 1 ) * COL_POSITION
+
+Where all variables are decimels/floats.
+
+`modifier` is a boolean, whether or not a certain key is considered a modifier (used in some effects).
+
+## Keycodes
+
+All RGB keycodes are currently shared with the RGBLIGHT system:
+
+	* `RGB_TOG` - toggle
+	* `RGB_MOD` - cycle through modes
+	* `RGB_HUI` - increase hue
+	* `RGB_HUD` - decrease hue
+	* `RGB_SAI` - increase saturation
+	* `RGB_SAD` - decrease saturation
+	* `RGB_VAI` - increase value
+	* `RGB_VAD` - decrease value
+
+
+	* `RGB_MODE_*` keycodes will generally work, but are not currently mapped to the correct effects for the RGB Matrix system
+
+## RGB Matrix Effects
+
+These are the effects that are currently available:
+
+	enum rgb_matrix_effects {
+		RGB_MATRIX_SOLID_COLOR = 1,
+	    RGB_MATRIX_SOLID_REACTIVE,
+	    RGB_MATRIX_ALPHAS_MODS,
+	    RGB_MATRIX_DUAL_BEACON,
+	    RGB_MATRIX_GRADIENT_UP_DOWN,
+	    RGB_MATRIX_RAINDROPS,
+	    RGB_MATRIX_CYCLE_ALL,
+	    RGB_MATRIX_CYCLE_LEFT_RIGHT,
+	    RGB_MATRIX_CYCLE_UP_DOWN,
+	    RGB_MATRIX_RAINBOW_BEACON,
+	    RGB_MATRIX_RAINBOW_PINWHEELS,
+	    RGB_MATRIX_RAINBOW_MOVING_CHEVRON,
+	    RGB_MATRIX_JELLYBEAN_RAINDROPS,
+	#ifdef RGB_MATRIX_KEYPRESSES
+	    RGB_MATRIX_SPLASH,
+	    RGB_MATRIX_MULTISPLASH,
+	    RGB_MATRIX_SOLID_SPLASH,
+	    RGB_MATRIX_SOLID_MULTISPLASH,
+	#endif
+	    RGB_MATRIX_EFFECT_MAX
+	};
+
+## Custom layer effects
+
+Custom layer effects can be done by defining this in your `<keyboard>.c`:
+
+    void rgb_matrix_indicators_kb(void) {
+    	// rgb_matrix_set_color(index, red, green, blue);
+    }
+
+A similar function works in the keymap as `rgb_matrix_indicators_user`.
+
+## Additional `config.h` Options
+
+	#define RGB_MATRIX_KEYPRESSES // reacts to keypresses (will slow down matrix scan by a lot)
+	#define RGB_MATRIX_KEYRELEASES // reacts to keyreleases (not recommened)
+	#define RGB_DISABLE_AFTER_TIMEOUT 0 // number of ticks to wait until disabling effects
+	#define RGB_DISABLE_WHEN_USB_SUSPENDED false // turn off effects when suspended
+    #define RGB_MATRIX_SKIP_FRAMES 1 // number of frames to skip when displaying animations (0 is full effect)
+
+## EEPROM storage
+
+The EEPROM for it is currently shared with the RGBLIGHT system (it's generally assumed only one RGB would be used at a time), but could be configured to use its own 32bit address with:
+
+    #define EECONFIG_RGB_MATRIX (uint32_t *)16
+
+Where `16` is an unused index from `eeconfig.h`.
+
+## Suspended state
+
+To use the suspend feature, add this to your `<keyboard>.c`:
+
+	void suspend_power_down_kb(void)
+	{
+	    rgb_matrix_set_suspend_state(true);
+	}
+
+	void suspend_wakeup_init_kb(void)
+	{
+	    rgb_matrix_set_suspend_state(false);
+	}
diff --git a/drivers/avr/TWIlib.c b/drivers/avr/TWIlib.c
new file mode 100644
index 0000000000..b39e3054a5
--- /dev/null
+++ b/drivers/avr/TWIlib.c
@@ -0,0 +1,232 @@
+/*
+ * TWIlib.c
+ *
+ *  Created: 6/01/2014 10:41:33 PM
+ *  Author: Chris Herring
+ *  http://www.chrisherring.net/all/tutorial-interrupt-driven-twi-interface-for-avr-part1/
+ */ 
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include "TWIlib.h"
+#include "util/delay.h"
+
+void TWIInit()
+{
+	TWIInfo.mode = Ready;
+	TWIInfo.errorCode = 0xFF;
+	TWIInfo.repStart = 0;
+	// Set pre-scalers (no pre-scaling)
+	TWSR = 0;
+	// Set bit rate
+	TWBR = ((F_CPU / TWI_FREQ) - 16) / 2;
+	// Enable TWI and interrupt
+	TWCR = (1 << TWIE) | (1 << TWEN);
+}
+
+uint8_t isTWIReady()
+{
+	if ( (TWIInfo.mode == Ready) | (TWIInfo.mode == RepeatedStartSent) )
+	{
+		return 1;
+	}
+	else
+	{
+		return 0;
+	}
+}
+
+uint8_t TWITransmitData(void *const TXdata, uint8_t dataLen, uint8_t repStart)
+{
+	if (dataLen <= TXMAXBUFLEN)
+	{
+		// Wait until ready
+		while (!isTWIReady()) {_delay_us(1);}
+		// Set repeated start mode
+		TWIInfo.repStart = repStart;
+		// Copy data into the transmit buffer
+		uint8_t *data = (uint8_t *)TXdata;
+		for (int i = 0; i < dataLen; i++)
+		{
+			TWITransmitBuffer[i] = data[i];
+		}
+		// Copy transmit info to global variables
+		TXBuffLen = dataLen;
+		TXBuffIndex = 0;
+		
+		// If a repeated start has been sent, then devices are already listening for an address
+		// and another start does not need to be sent. 
+		if (TWIInfo.mode == RepeatedStartSent)
+		{
+			TWIInfo.mode = Initializing;
+			TWDR = TWITransmitBuffer[TXBuffIndex++]; // Load data to transmit buffer
+			TWISendTransmit(); // Send the data
+		}
+		else // Otherwise, just send the normal start signal to begin transmission.
+		{
+			TWIInfo.mode = Initializing;
+			TWISendStart();
+		}
+		
+	}
+	else
+	{
+		return 1; // return an error if data length is longer than buffer
+	}
+	return 0;
+}
+
+uint8_t TWIReadData(uint8_t TWIaddr, uint8_t bytesToRead, uint8_t repStart)
+{
+	// Check if number of bytes to read can fit in the RXbuffer
+	if (bytesToRead < RXMAXBUFLEN)
+	{
+		// Reset buffer index and set RXBuffLen to the number of bytes to read
+		RXBuffIndex = 0;
+		RXBuffLen = bytesToRead;
+		// Create the one value array for the address to be transmitted
+		uint8_t TXdata[1];
+		// Shift the address and AND a 1 into the read write bit (set to write mode)
+		TXdata[0] = (TWIaddr << 1) | 0x01;
+		// Use the TWITransmitData function to initialize the transfer and address the slave
+		TWITransmitData(TXdata, 1, repStart);
+	}
+	else
+	{
+		return 0;
+	}
+	return 1;
+}
+
+ISR (TWI_vect)
+{
+	switch (TWI_STATUS)
+	{
+		// ----\/ ---- MASTER TRANSMITTER OR WRITING ADDRESS ----\/ ----  //
+		case TWI_MT_SLAW_ACK: // SLA+W transmitted and ACK received
+		// Set mode to Master Transmitter
+		TWIInfo.mode = MasterTransmitter;
+		case TWI_START_SENT: // Start condition has been transmitted
+		case TWI_MT_DATA_ACK: // Data byte has been transmitted, ACK received
+			if (TXBuffIndex < TXBuffLen) // If there is more data to send
+			{
+				TWDR = TWITransmitBuffer[TXBuffIndex++]; // Load data to transmit buffer
+				TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
+				TWISendTransmit(); // Send the data
+			}
+			// This transmission is complete however do not release bus yet
+			else if (TWIInfo.repStart)
+			{
+				TWIInfo.errorCode = 0xFF;
+				TWISendStart();
+			}
+			// All transmissions are complete, exit
+			else
+			{
+				TWIInfo.mode = Ready;
+				TWIInfo.errorCode = 0xFF;
+				TWISendStop();
+			}
+			break;
+		
+		// ----\/ ---- MASTER RECEIVER ----\/ ----  //
+		
+		case TWI_MR_SLAR_ACK: // SLA+R has been transmitted, ACK has been received
+			// Switch to Master Receiver mode
+			TWIInfo.mode = MasterReceiver;
+			// If there is more than one byte to be read, receive data byte and return an ACK
+			if (RXBuffIndex < RXBuffLen-1)
+			{
+				TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
+				TWISendACK();
+			}
+			// Otherwise when a data byte (the only data byte) is received, return NACK
+			else
+			{
+				TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
+				TWISendNACK();
+			}
+			break;
+		
+		case TWI_MR_DATA_ACK: // Data has been received, ACK has been transmitted.
+		
+			/// -- HANDLE DATA BYTE --- ///
+			TWIReceiveBuffer[RXBuffIndex++] = TWDR;
+			// If there is more than one byte to be read, receive data byte and return an ACK
+			if (RXBuffIndex < RXBuffLen-1)
+			{
+				TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
+				TWISendACK();
+			}
+			// Otherwise when a data byte (the only data byte) is received, return NACK
+			else
+			{
+				TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
+				TWISendNACK();
+			}
+			break;
+		
+		case TWI_MR_DATA_NACK: // Data byte has been received, NACK has been transmitted. End of transmission.
+		
+			/// -- HANDLE DATA BYTE --- ///
+			TWIReceiveBuffer[RXBuffIndex++] = TWDR;	
+			// This transmission is complete however do not release bus yet
+			if (TWIInfo.repStart)
+			{
+				TWIInfo.errorCode = 0xFF;
+				TWISendStart();
+			}
+			// All transmissions are complete, exit
+			else
+			{
+				TWIInfo.mode = Ready;
+				TWIInfo.errorCode = 0xFF;
+				TWISendStop();
+			}
+			break;
+		
+		// ----\/ ---- MT and MR common ----\/ ---- //
+		
+		case TWI_MR_SLAR_NACK: // SLA+R transmitted, NACK received
+		case TWI_MT_SLAW_NACK: // SLA+W transmitted, NACK received
+		case TWI_MT_DATA_NACK: // Data byte has been transmitted, NACK received
+		case TWI_LOST_ARBIT: // Arbitration has been lost
+			// Return error and send stop and set mode to ready
+			if (TWIInfo.repStart)
+			{				
+				TWIInfo.errorCode = TWI_STATUS;
+				TWISendStart();
+			}
+			// All transmissions are complete, exit
+			else
+			{
+				TWIInfo.mode = Ready;
+				TWIInfo.errorCode = TWI_STATUS;
+				TWISendStop();
+			}
+			break;
+		case TWI_REP_START_SENT: // Repeated start has been transmitted
+			// Set the mode but DO NOT clear TWINT as the next data is not yet ready
+			TWIInfo.mode = RepeatedStartSent;
+			break;
+		
+		// ----\/ ---- SLAVE RECEIVER ----\/ ----  //
+		
+		// TODO  IMPLEMENT SLAVE RECEIVER FUNCTIONALITY
+		
+		// ----\/ ---- SLAVE TRANSMITTER ----\/ ----  //
+		
+		// TODO  IMPLEMENT SLAVE TRANSMITTER FUNCTIONALITY
+		
+		// ----\/ ---- MISCELLANEOUS STATES ----\/ ----  //
+		case TWI_NO_RELEVANT_INFO: // It is not really possible to get into this ISR on this condition
+								   // Rather, it is there to be manually set between operations
+			break;
+		case TWI_ILLEGAL_START_STOP: // Illegal START/STOP, abort and return error
+			TWIInfo.errorCode = TWI_ILLEGAL_START_STOP;
+			TWIInfo.mode = Ready;
+			TWISendStop();
+			break;
+	}
+	
+}
diff --git a/drivers/avr/TWIlib.h b/drivers/avr/TWIlib.h
new file mode 100644
index 0000000000..23fd1f09aa
--- /dev/null
+++ b/drivers/avr/TWIlib.h
@@ -0,0 +1,82 @@
+/*
+ * TWIlib.h
+ *
+ * Created: 6/01/2014 10:38:42 PM
+ *  Author: Chris Herring
+ *  http://www.chrisherring.net/all/tutorial-interrupt-driven-twi-interface-for-avr-part1/
+ */ 
+
+
+#ifndef TWILIB_H_
+#define TWILIB_H_
+// TWI bit rate (was 100000)
+#define TWI_FREQ 400000
+// Get TWI status
+#define TWI_STATUS	(TWSR & 0xF8) 
+// Transmit buffer length
+#define TXMAXBUFLEN 20
+// Receive buffer length
+#define RXMAXBUFLEN 20
+// Global transmit buffer
+uint8_t TWITransmitBuffer[TXMAXBUFLEN];
+// Global receive buffer
+volatile uint8_t TWIReceiveBuffer[RXMAXBUFLEN];
+// Buffer indexes
+volatile int TXBuffIndex; // Index of the transmit buffer. Is volatile, can change at any time.
+int RXBuffIndex; // Current index in the receive buffer
+// Buffer lengths
+int TXBuffLen; // The total length of the transmit buffer
+int RXBuffLen; // The total number of bytes to read (should be less than RXMAXBUFFLEN)
+
+typedef enum {
+	Ready,
+	Initializing,
+	RepeatedStartSent,
+	MasterTransmitter,
+	MasterReceiver,
+	SlaceTransmitter,
+	SlaveReciever
+	} TWIMode;
+
+ typedef struct TWIInfoStruct{
+	TWIMode mode;
+	uint8_t errorCode;
+	uint8_t repStart;	
+	}TWIInfoStruct;
+TWIInfoStruct TWIInfo;
+
+
+// TWI Status Codes
+#define TWI_START_SENT			0x08 // Start sent
+#define TWI_REP_START_SENT		0x10 // Repeated Start sent
+// Master Transmitter Mode
+#define TWI_MT_SLAW_ACK			0x18 // SLA+W sent and ACK received
+#define TWI_MT_SLAW_NACK		0x20 // SLA+W sent and NACK received
+#define TWI_MT_DATA_ACK			0x28 // DATA sent and ACK received
+#define TWI_MT_DATA_NACK		0x30 // DATA sent and NACK received
+// Master Receiver Mode
+#define TWI_MR_SLAR_ACK			0x40 // SLA+R sent, ACK received
+#define TWI_MR_SLAR_NACK		0x48 // SLA+R sent, NACK received
+#define TWI_MR_DATA_ACK			0x50 // Data received, ACK returned
+#define TWI_MR_DATA_NACK		0x58 // Data received, NACK returned
+
+// Miscellaneous States
+#define TWI_LOST_ARBIT			0x38 // Arbitration has been lost
+#define TWI_NO_RELEVANT_INFO	0xF8 // No relevant information available
+#define TWI_ILLEGAL_START_STOP	0x00 // Illegal START or STOP condition has been detected
+#define TWI_SUCCESS				0xFF // Successful transfer, this state is impossible from TWSR as bit2 is 0 and read only
+
+
+#define TWISendStart()		(TWCR = (1<<TWINT)|(1<<TWSTA)|(1<<TWEN)|(1<<TWIE)) // Send the START signal, enable interrupts and TWI, clear TWINT flag to resume transfer.
+#define TWISendStop()		(TWCR = (1<<TWINT)|(1<<TWSTO)|(1<<TWEN)|(1<<TWIE)) // Send the STOP signal, enable interrupts and TWI, clear TWINT flag.
+#define TWISendTransmit()	(TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE)) // Used to resume a transfer, clear TWINT and ensure that TWI and interrupts are enabled.
+#define TWISendACK()		(TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE)|(1<<TWEA)) // FOR MR mode. Resume a transfer, ensure that TWI and interrupts are enabled and respond with an ACK if the device is addressed as a slave or after it receives a byte.
+#define TWISendNACK()		(TWCR = (1<<TWINT)|(1<<TWEN)|(1<<TWIE)) // FOR MR mode. Resume a transfer, ensure that TWI and interrupts are enabled but DO NOT respond with an ACK if the device is addressed as a slave or after it receives a byte.
+
+// Function declarations
+uint8_t TWITransmitData(void *const TXdata, uint8_t dataLen, uint8_t repStart);
+void TWIInit(void);
+uint8_t TWIReadData(uint8_t TWIaddr, uint8_t bytesToRead, uint8_t repStart);
+uint8_t isTWIReady(void);
+
+#endif // TWICOMMS_H_ 
\ No newline at end of file
diff --git a/drivers/avr/is31fl3731.c b/drivers/avr/is31fl3731.c
new file mode 100644
index 0000000000..e5941cf41e
--- /dev/null
+++ b/drivers/avr/is31fl3731.c
@@ -0,0 +1,258 @@
+/* Copyright 2017 Jason Williams
+ * Copyright 2018 Jack Humbert
+ *
+ * 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 "is31fl3731.h"
+#include <avr/interrupt.h>
+#include <avr/io.h>
+#include <util/delay.h>
+#include <string.h>
+#include "TWIlib.h"
+#include "progmem.h"
+
+// This is a 7-bit address, that gets left-shifted and bit 0
+// set to 0 for write, 1 for read (as per I2C protocol)
+// The address will vary depending on your wiring:
+// 0b1110100 AD <-> GND
+// 0b1110111 AD <-> VCC
+// 0b1110101 AD <-> SCL
+// 0b1110110 AD <-> SDA
+#define ISSI_ADDR_DEFAULT 0x74
+
+#define ISSI_REG_CONFIG  0x00
+#define ISSI_REG_CONFIG_PICTUREMODE 0x00
+#define ISSI_REG_CONFIG_AUTOPLAYMODE 0x08
+#define ISSI_REG_CONFIG_AUDIOPLAYMODE 0x18
+
+#define ISSI_CONF_PICTUREMODE 0x00
+#define ISSI_CONF_AUTOFRAMEMODE 0x04
+#define ISSI_CONF_AUDIOMODE 0x08
+
+#define ISSI_REG_PICTUREFRAME  0x01
+
+#define ISSI_REG_SHUTDOWN 0x0A
+#define ISSI_REG_AUDIOSYNC 0x06
+
+#define ISSI_COMMANDREGISTER 0xFD
+#define ISSI_BANK_FUNCTIONREG 0x0B    // helpfully called 'page nine'
+
+// Transfer buffer for TWITransmitData()
+uint8_t g_twi_transfer_buffer[TXMAXBUFLEN];
+
+// These buffers match the IS31FL3731 PWM registers 0x24-0xB3.
+// Storing them like this is optimal for I2C transfers to the registers.
+// We could optimize this and take out the unused registers from these
+// buffers and the transfers in IS31FL3731_write_pwm_buffer() but it's
+// probably not worth the extra complexity.
+uint8_t g_pwm_buffer[DRIVER_COUNT][144];
+bool g_pwm_buffer_update_required = false;
+
+uint8_t g_led_control_registers[DRIVER_COUNT][18] = { { 0 }, { 0 } };
+bool g_led_control_registers_update_required = false;
+
+// This is the bit pattern in the LED control registers
+// (for matrix A, add one to register for matrix B)
+//
+//  reg -  b7  b6  b5  b4  b3  b2  b1  b0
+// 0x00 - R08,R07,R06,R05,R04,R03,R02,R01
+// 0x02 - G08,G07,G06,G05,G04,G03,G02,R00
+// 0x04 - B08,B07,B06,B05,B04,B03,G01,G00
+// 0x06 -  - , - , - , - , - ,B02,B01,B00
+// 0x08 -  - , - , - , - , - , - , - , -
+// 0x0A - B17,B16,B15, - , - , - , - , -
+// 0x0C - G17,G16,B14,B13,B12,B11,B10,B09
+// 0x0E - R17,G15,G14,G13,G12,G11,G10,G09
+// 0x10 - R16,R15,R14,R13,R12,R11,R10,R09
+
+
+void IS31FL3731_write_register( uint8_t addr, uint8_t reg, uint8_t data )
+{
+	g_twi_transfer_buffer[0] = (addr << 1) | 0x00;
+	g_twi_transfer_buffer[1] = reg;
+	g_twi_transfer_buffer[2] = data;
+
+	// Set the error code to have no relevant information
+	TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
+	// Continuously attempt to transmit data until a successful transmission occurs
+	//while ( TWIInfo.errorCode != 0xFF )
+	//{
+		TWITransmitData( g_twi_transfer_buffer, 3, 0 );
+	//}
+}
+
+void IS31FL3731_write_pwm_buffer( uint8_t addr, uint8_t *pwm_buffer )
+{
+	// assumes bank is already selected
+
+	// transmit PWM registers in 9 transfers of 16 bytes
+	// g_twi_transfer_buffer[] is 20 bytes
+
+	// set the I2C address
+	g_twi_transfer_buffer[0] = (addr << 1) | 0x00;
+
+	// iterate over the pwm_buffer contents at 16 byte intervals
+	for ( int i = 0; i < 144; i += 16 )
+	{
+		// set the first register, e.g. 0x24, 0x34, 0x44, etc.
+		g_twi_transfer_buffer[1] = 0x24 + i;
+		// copy the data from i to i+15
+		// device will auto-increment register for data after the first byte
+		// thus this sets registers 0x24-0x33, 0x34-0x43, etc. in one transfer
+		for ( int j = 0; j < 16; j++ )
+		{
+			g_twi_transfer_buffer[2 + j] = pwm_buffer[i + j];
+		}
+
+		// Set the error code to have no relevant information
+		TWIInfo.errorCode = TWI_NO_RELEVANT_INFO;
+		// Continuously attempt to transmit data until a successful transmission occurs
+		while ( TWIInfo.errorCode != 0xFF )
+		{
+			TWITransmitData( g_twi_transfer_buffer, 16 + 2, 0 );
+		}
+	}
+}
+
+void IS31FL3731_init( uint8_t addr )
+{
+	// In order to avoid the LEDs being driven with garbage data
+	// in the LED driver's PWM registers, first enable software shutdown,
+	// then set up the mode and other settings, clear the PWM registers,
+	// then disable software shutdown.
+
+	// select "function register" bank
+	IS31FL3731_write_register( addr, ISSI_COMMANDREGISTER, ISSI_BANK_FUNCTIONREG );
+
+	// enable software shutdown
+	IS31FL3731_write_register( addr, ISSI_REG_SHUTDOWN, 0x00 );
+	// this delay was copied from other drivers, might not be needed
+	_delay_ms( 10 );
+
+	// picture mode
+	IS31FL3731_write_register( addr, ISSI_REG_CONFIG, ISSI_REG_CONFIG_PICTUREMODE );
+	// display frame 0
+	IS31FL3731_write_register( addr, ISSI_REG_PICTUREFRAME, 0x00 );
+	// audio sync off
+	IS31FL3731_write_register( addr, ISSI_REG_AUDIOSYNC, 0x00 );
+
+	// select bank 0
+	IS31FL3731_write_register( addr, ISSI_COMMANDREGISTER, 0 );
+
+	// turn off all LEDs in the LED control register
+	for ( int i = 0x00; i <= 0x11; i++ )
+	{
+		IS31FL3731_write_register( addr, i, 0x00 );
+	}
+
+	// turn off all LEDs in the blink control register (not really needed)
+	for ( int i = 0x12; i <= 0x23; i++ )
+	{
+		IS31FL3731_write_register( addr, i, 0x00 );
+	}
+
+	// set PWM on all LEDs to 0
+	for ( int i = 0x24; i <= 0xB3; i++ )
+	{
+		IS31FL3731_write_register( addr, i, 0x00 );
+	}
+
+	// select "function register" bank
+	IS31FL3731_write_register( addr, ISSI_COMMANDREGISTER, ISSI_BANK_FUNCTIONREG );
+
+	// disable software shutdown
+	IS31FL3731_write_register( addr, ISSI_REG_SHUTDOWN, 0x01 );
+
+	// select bank 0 and leave it selected.
+	// most usage after initialization is just writing PWM buffers in bank 0
+	// as there's not much point in double-buffering
+	IS31FL3731_write_register( addr, ISSI_COMMANDREGISTER, 0 );
+}
+
+void IS31FL3731_set_color( int index, uint8_t red, uint8_t green, uint8_t blue )
+{
+	if ( index >= 0 && index < DRIVER_LED_TOTAL ) {
+		is31_led led = g_is31_leds[index];
+
+		// Subtract 0x24 to get the second index of g_pwm_buffer
+		g_pwm_buffer[led.driver][led.r - 0x24] = red;
+		g_pwm_buffer[led.driver][led.g - 0x24] = green;
+		g_pwm_buffer[led.driver][led.b - 0x24] = blue;
+		g_pwm_buffer_update_required = true;
+	}
+}
+
+void IS31FL3731_set_color_all( uint8_t red, uint8_t green, uint8_t blue )
+{
+	for ( int i = 0; i < DRIVER_LED_TOTAL; i++ )
+	{
+		IS31FL3731_set_color( i, red, green, blue );
+	}
+}
+
+void IS31FL3731_set_led_control_register( uint8_t index, bool red, bool green, bool blue )
+{
+	is31_led led = g_is31_leds[index];
+
+  uint8_t control_register_r = (led.r - 0x24) / 8;
+  uint8_t control_register_g = (led.g - 0x24) / 8;
+  uint8_t control_register_b = (led.b - 0x24) / 8;
+  uint8_t bit_r = (led.r - 0x24) % 8;
+  uint8_t bit_g = (led.g - 0x24) % 8;
+  uint8_t bit_b = (led.b - 0x24) % 8;
+
+	if ( red ) {
+		g_led_control_registers[led.driver][control_register_r] |= (1 << bit_r);
+	} else {
+		g_led_control_registers[led.driver][control_register_r] &= ~(1 << bit_r);
+	}
+	if ( green ) {
+		g_led_control_registers[led.driver][control_register_g] |= (1 << bit_g);
+	} else {
+		g_led_control_registers[led.driver][control_register_g] &= ~(1 << bit_g);
+	}
+	if ( blue ) {
+		g_led_control_registers[led.driver][control_register_b] |= (1 << bit_b);
+	} else {
+		g_led_control_registers[led.driver][control_register_b] &= ~(1 << bit_b);
+	}
+
+	g_led_control_registers_update_required = true;
+
+
+}
+
+void IS31FL3731_update_pwm_buffers( uint8_t addr1, uint8_t addr2 )
+{
+	if ( g_pwm_buffer_update_required )
+	{
+		IS31FL3731_write_pwm_buffer( addr1, g_pwm_buffer[0] );
+		IS31FL3731_write_pwm_buffer( addr2, g_pwm_buffer[1] );
+	}
+	g_pwm_buffer_update_required = false;
+}
+
+void IS31FL3731_update_led_control_registers( uint8_t addr1, uint8_t addr2 )
+{
+	if ( g_led_control_registers_update_required )
+	{
+		for ( int i=0; i<18; i++ )
+		{
+			IS31FL3731_write_register(addr1, i, g_led_control_registers[0][i] );
+			IS31FL3731_write_register(addr2, i, g_led_control_registers[1][i] );
+		}
+	}
+}
+
diff --git a/drivers/avr/is31fl3731.h b/drivers/avr/is31fl3731.h
new file mode 100644
index 0000000000..3d30fc67b7
--- /dev/null
+++ b/drivers/avr/is31fl3731.h
@@ -0,0 +1,214 @@
+/* Copyright 2017 Jason Williams
+ * Copyright 2018 Jack Humbert
+ *
+ * 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 IS31FL3731_DRIVER_H
+#define IS31FL3731_DRIVER_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+typedef struct is31_led {
+	uint8_t driver:2;
+  uint8_t r;
+  uint8_t g;
+  uint8_t b;
+} __attribute__((packed)) is31_led;
+
+extern const is31_led g_is31_leds[DRIVER_LED_TOTAL];
+
+void IS31FL3731_init( uint8_t addr );
+void IS31FL3731_write_register( uint8_t addr, uint8_t reg, uint8_t data );
+void IS31FL3731_write_pwm_buffer( uint8_t addr, uint8_t *pwm_buffer );
+
+void IS31FL3731_set_color( int index, uint8_t red, uint8_t green, uint8_t blue );
+void IS31FL3731_set_color_all( uint8_t red, uint8_t green, uint8_t blue );
+
+void IS31FL3731_set_led_control_register( uint8_t index, bool red, bool green, bool blue );
+
+// This should not be called from an interrupt
+// (eg. from a timer interrupt).
+// Call this while idle (in between matrix scans).
+// If the buffer is dirty, it will update the driver with the buffer.
+void IS31FL3731_update_pwm_buffers( uint8_t addr1, uint8_t addr2 );
+void IS31FL3731_update_led_control_registers( uint8_t addr1, uint8_t addr2 );
+
+#define C1_1  0x24
+#define C1_2  0x25
+#define C1_3  0x26
+#define C1_4  0x27
+#define C1_5  0x28
+#define C1_6  0x29
+#define C1_7  0x2A
+#define C1_8  0x2B
+
+#define C1_9  0x2C
+#define C1_10 0x2D
+#define C1_11 0x2E
+#define C1_12 0x2F
+#define C1_13 0x30
+#define C1_14 0x31
+#define C1_15 0x32
+#define C1_16 0x33
+
+#define C2_1  0x34
+#define C2_2  0x35
+#define C2_3  0x36
+#define C2_4  0x37
+#define C2_5  0x38
+#define C2_6  0x39
+#define C2_7  0x3A
+#define C2_8  0x3B
+
+#define C2_9  0x3C
+#define C2_10 0x3D
+#define C2_11 0x3E
+#define C2_12 0x3F
+#define C2_13 0x40
+#define C2_14 0x41
+#define C2_15 0x42
+#define C2_16 0x43
+
+#define C3_1  0x44
+#define C3_2  0x45
+#define C3_3  0x46
+#define C3_4  0x47
+#define C3_5  0x48
+#define C3_6  0x49
+#define C3_7  0x4A
+#define C3_8  0x4B
+
+#define C3_9  0x4C
+#define C3_10 0x4D
+#define C3_11 0x4E
+#define C3_12 0x4F
+#define C3_13 0x50
+#define C3_14 0x51
+#define C3_15 0x52
+#define C3_16 0x53
+
+#define C4_1  0x54
+#define C4_2  0x55
+#define C4_3  0x56
+#define C4_4  0x57
+#define C4_5  0x58
+#define C4_6  0x59
+#define C4_7  0x5A
+#define C4_8  0x5B
+
+#define C4_9  0x5C
+#define C4_10 0x5D
+#define C4_11 0x5E
+#define C4_12 0x5F
+#define C4_13 0x60
+#define C4_14 0x61
+#define C4_15 0x62
+#define C4_16 0x63
+
+#define C5_1  0x64
+#define C5_2  0x65
+#define C5_3  0x66
+#define C5_4  0x67
+#define C5_5  0x68
+#define C5_6  0x69
+#define C5_7  0x6A
+#define C5_8  0x6B
+
+#define C5_9  0x6C
+#define C5_10 0x6D
+#define C5_11 0x6E
+#define C5_12 0x6F
+#define C5_13 0x70
+#define C5_14 0x71
+#define C5_15 0x72
+#define C5_16 0x73
+
+#define C6_1  0x74
+#define C6_2  0x75
+#define C6_3  0x76
+#define C6_4  0x77
+#define C6_5  0x78
+#define C6_6  0x79
+#define C6_7  0x7A
+#define C6_8  0x7B
+
+#define C6_9  0x7C
+#define C6_10 0x7D