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+# LED Matrix Lighting
+
+This feature allows you to use LED matrices driven by external drivers. It hooks into the backlight system so you can use the same keycodes as backlighting to control it.
+
+If you want to use RGB LED's you should use the [RGB Matrix Subsystem](feature_rgb_matrix.md) instead.
+
+## Driver configuration
+
+### IS31FL3731
+
+There is basic support for addressable LED matrix lighting with the I2C IS31FL3731 RGB controller. To enable it, add this to your `rules.mk`:
+
+    LED_MATRIX_ENABLE = IS31FL3731
+    
+You can use between 1 and 4 IS31FL3731 IC's. Do not specify `LED_DRIVER_ADDR_<N>` defines for IC's that are not present on your keyboard. You can define the following items in `config.h`:
+
+| Variable | Description | Default |
+|----------|-------------|---------|
+| `ISSI_TIMEOUT` | (Optional) How long to wait for i2c messages | 100 |
+| `ISSI_PERSISTENCE` | (Optional) Retry failed messages this many times | 0 |
+| `LED_DRIVER_COUNT` | (Required) How many LED driver IC's are present | |
+| `LED_DRIVER_LED_COUNT` | (Required) How many LED lights are present across all drivers | |
+| `LED_DRIVER_ADDR_1` | (Required) Address for the first LED driver | |
+| `LED_DRIVER_ADDR_2` | (Optional) Address for the second LED driver | |
+| `LED_DRIVER_ADDR_3` | (Optional) Address for the third LED driver | |
+| `LED_DRIVER_ADDR_4` | (Optional) Address for the fourth LED driver | |
+
+Here is an example using 2 drivers.
+
+        // 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 LED_DRIVER_ADDR_1 0b1110100
+        #define LED_DRIVER_ADDR_2 0b1110110
+
+        #define LED_DRIVER_COUNT 2
+        #define LED_DRIVER_1_LED_COUNT 25
+        #define LED_DRIVER_2_LED_COUNT 24
+        #define LED_DRIVER_LED_COUNT LED_DRIVER_1_LED_TOTAL + LED_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
+         *   |  LED address
+         *   |  | */
+            {0, 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) and the header file `drivers/issi/is31fl3731-simple.h`. The `driver` is the index of the driver you defined in your `config.h` (`0`, `1`, `2`, or `3` ).
+
+## Keycodes
+
+All LED matrix keycodes are currently shared with the [backlight system](feature_backlight.md).
+
+## LED Matrix Effects
+
+Currently no LED matrix effects have been created.
+
+## Custom layer effects
+
+Custom layer effects can be done by defining this in your `<keyboard>.c`:
+
+    void led_matrix_indicators_kb(void) {
+        led_matrix_set_index_value(index, value);
+    }
+
+A similar function works in the keymap as `led_matrix_indicators_user`.
+
+## Suspended state
+
+To use the suspend feature, add this to your `<keyboard>.c`:
+
+        void suspend_power_down_kb(void)
+        {
+            led_matrix_set_suspend_state(true);
+        }
+
+        void suspend_wakeup_init_kb(void)
+        {
+            led_matrix_set_suspend_state(false);
+        }