20 files changed, 434 insertions, 257 deletions

diff --git a/docs/_summary.md b/docs/_summary.md
index 5af0046ab..526caf926 100644
--- a/docs/_summary.md
+++ b/docs/_summary.md
@@ -138,6 +138,7 @@
       * [WS2812 Driver](ws2812_driver.md)
       * [EEPROM Driver](eeprom_driver.md)
       * ['serial' Driver](serial_driver.md)
+      * [UART Driver](uart_driver.md)
     * [GPIO Controls](internals_gpio_control.md)
     * [Keyboard Guidelines](hardware_keyboard_guidelines.md)
 
@@ -159,6 +160,7 @@
     * [Contributing to QMK](contributing.md)
     * [Translating the QMK Docs](translating.md)
     * [Config Options](config_options.md)
+    * [Data Driven Configuration](data_driven_config.md)
     * [Make Documentation](getting_started_make_guide.md)
     * [Documentation Best Practices](documentation_best_practices.md)
     * [Documentation Templates](documentation_templates.md)
diff --git a/docs/compatible_microcontrollers.md b/docs/compatible_microcontrollers.md
index 1bf707224..c1287bc33 100644
--- a/docs/compatible_microcontrollers.md
+++ b/docs/compatible_microcontrollers.md
@@ -9,6 +9,7 @@ The following use [LUFA](https://www.fourwalledcubicle.com/LUFA.php) as the USB
 * [ATmega16U2](https://www.microchip.com/wwwproducts/en/ATmega16U2) / [ATmega32U2](https://www.microchip.com/wwwproducts/en/ATmega32U2)
 * [ATmega16U4](https://www.microchip.com/wwwproducts/en/ATmega16U4) / [ATmega32U4](https://www.microchip.com/wwwproducts/en/ATmega32U4)
 * [AT90USB64](https://www.microchip.com/wwwproducts/en/AT90USB646) / [AT90USB128](https://www.microchip.com/wwwproducts/en/AT90USB1286)
+* [AT90USB162](https://www.microchip.com/wwwproducts/en/AT90USB162)
 
 Certain MCUs which do not have native USB will use [V-USB](https://www.obdev.at/products/vusb/index.html) instead:
 
diff --git a/docs/data_driven_config.md b/docs/data_driven_config.md
new file mode 100644
index 000000000..c2ad4fed8
--- /dev/null
+++ b/docs/data_driven_config.md
@@ -0,0 +1,91 @@
+# Data Driven Configuration
+
+This page describes how QMK's data driven JSON configuration system works. It is aimed at developers who want to work on QMK itself.
+
+## History
+
+Historically QMK has been configured through a combination of two mechanisms- `rules.mk` and `config.h`. While this worked well when QMK was only a handful of keyboards we've grown to encompass nearly 1500 supported keyboards. That extrapolates out to 6000 configuration files under `keyboards/` alone! The freeform nature of these files and the unique patterns people have used to avoid duplication have made ongoing maintenance a challenge, and a large number of our keyboards follow patterns that are outdated and sometimes harder to understand.
+
+We have also been working on bringing the power of QMK to people who aren't comformable with a CLI, and other projects such as VIA are working to make using QMK as easy as installing a program. These tools need information about how a keyboard is laid out or what pins and features are available so that users can take full advantage of QMK. We introduced `info.json` as a first step towards this. The QMK API is an effort to combine these 3 sources of information- `config.h`, `rules.mk`, and `info.json`- into a single source of truth that end-user tools can use.
+
+Now we have support for generating `rules.mk` and `config.h` values from `info.json`, allowing us to have a single source of truth. This will allow us to use automated tooling to maintain keyboards saving a lot of time and maintenance work.
+
+## Overview
+
+On the C side of things nothing changes. When you need to create a new rule or define you follow the same process:
+
+1. Add it to `docs/config_options.md`
+1. Set a default in the appropriate core file
+1. Add your ifdef statements as needed
+
+You will then need to add support for your new configuration to `info.json`. The basic process is:
+
+1. Add it to the schema in `data/schemas/keyboards.jsonschema`
+1. Add a mapping in `data/maps`
+1. (optional and discoraged) Add code to extract/generate it to:
+  * `lib/python/qmk/info.py`
+  * `lib/python/qmk/cli/generate/config_h.py`
+  * `lib/python/qmk/cli/generate/rules_mk.py`
+
+## Adding an option to info.json
+
+This section describes adding support for a `config.h`/`rules.mk` value to info.json.
+
+### Add it to the schema
+
+QMK maintains [jsonschema](https://json-schema.org/) files in `data/schemas`. The values that go into keyboard-specific `info.json` files are kept in `keyboard.jsonschema`. Any value you want to make available to end users to edit must go in here.
+
+In some cases you can simply add a new top-level key. Some examples to follow are `keyboard_name`, `maintainer`, `processor`, and `url`. This is appropriate when your option is self-contained and not directly related to other options.
+
+In other cases you should group like options together in an `object`. This is particularly true when adding support for a feature. Some examples to follow for this are `indicators`, `matrix_pins`, and `rgblight`. If you are not sure how to integrate your new option(s) [open an issue](https://github.com/qmk/qmk_firmware/issues/new?assignees=&labels=cli%2C+python&template=other_issues.md&title=) or [join #cli on Discord](https://discord.gg/heQPAgy) and start a conversation there.
+
+### Add a mapping
+
+In most cases you can add a simple mapping. These are maintained as JSON files in `data/mappings/info_config.json` and `data/mappings/info_rules.json`, and control mapping for `config.h` and `rules.mk`, respectively. Each mapping is keyed by the `config.h` or `rules.mk` variable, and the value is a hash with the following keys:
+
+* `info_key`: (required) The location within `info.json` for this value. See below.
+* `value_type`: (optional) Default `str`. The format for this variable's value. See below.
+* `to_json`: (optional) Default `true`. Set to `false` to exclude this mapping from info.json
+* `to_c`: (optional) Default `true`. Set to `false` to exclude this mapping from config.h
+* `warn_duplicate`: (optional) Default `true`. Set to `false` to turn off warning when a value exists in both places
+
+#### Info Key
+
+We use JSON dot notation to address variables within info.json. For example, to access `info_json["rgblight"]["split_count"]` I would specify `rgblight.split_count`. This allows you to address deeply nested keys with a simple string.
+
+Under the hood we use [Dotty Dict](https://dotty-dict.readthedocs.io/en/latest/), you can refer to that documentation for how these strings are converted to object access.
+
+#### Value Types
+
+By default we treat all values as simple strings. If your value is more complex you can use one of these types to intelligently parse the data:
+
+* `array`: A comma separated array of strings
+* `array.int`: A comma separated array of integers
+* `int`: An integer
+* `hex`: A number formatted as hex
+* `list`: A space separate array of strings
+* `mapping`: A hash of key/value pairs
+
+### Add code to extract it
+
+Most use cases can be solved by the mapping files described above. If yours can't you can instead write code to extract your config values.
+
+Whenever QMK generates a complete `info.json` it extracts information from `config.h` and `rules.mk`. You will need to add code for your new config value to `lib/python/qmk/info.py`. Typically this means adding a new `_extract_<feature>()` function and then calling your function in either `_extract_config_h()` or `_extract_rules_mk()`.
+
+If you are not sure how to edit this file or are not comfortable with Python [open an issue](https://github.com/qmk/qmk_firmware/issues/new?assignees=&labels=cli%2C+python&template=other_issues.md&title=) or [join #cli on Discord](https://discord.gg/heQPAgy) and someone can help you with this part.
+
+### Add code to generate it
+
+The final piece of the puzzle is providing your new option to the build system. This is done by generating two files:
+
+* `.build/obj_<keyboard>/src/info_config.h`
+* `.build/obj_<keyboard>/src/rules.mk`
+
+These two files are generated by the code here:
+
+* `lib/python/qmk/cli/generate/config_h.py`
+* `lib/python/qmk/cli/generate/rules_mk.py`
+
+For `config.h` values you'll need to write a function for your rule(s) and call that function in `generate_config_h()`.
+
+If you have a new top-level `info.json` key for `rules.mk` you can simply add your keys to `info_to_rules` at the top of `lib/python/qmk/cli/generate/rules_mk.py`. Otherwise you'll need to create a new if block for your feature in `generate_rules_mk()`.
diff --git a/docs/feature_backlight.md b/docs/feature_backlight.md
index a558af64e..2adb16e4a 100644
--- a/docs/feature_backlight.md
+++ b/docs/feature_backlight.md
@@ -93,18 +93,18 @@ BACKLIGHT_DRIVER = pwm
 
 On AVR boards, QMK automatically decides which driver to use according to the following table:
 
-|Backlight Pin|AT90USB64/128|ATmega16/32U4|ATmega16/32U2|ATmega32A|ATmega328/P|
-|-------------|-------------|-------------|-------------|---------|-----------|
-|`B1`         |             |             |             |         |Timer 1    |
-|`B2`         |             |             |             |         |Timer 1    |
-|`B5`         |Timer 1      |Timer 1      |             |         |           |
-|`B6`         |Timer 1      |Timer 1      |             |         |           |
-|`B7`         |Timer 1      |Timer 1      |Timer 1      |         |           |
-|`C4`         |Timer 3      |             |             |         |           |
-|`C5`         |Timer 3      |             |Timer 1      |         |           |
-|`C6`         |Timer 3      |Timer 3      |Timer 1      |         |           |
-|`D4`         |             |             |             |Timer 1  |           |
-|`D5`         |             |             |             |Timer 1  |           |
+|Backlight Pin|AT90USB64/128|AT90USB162|ATmega16/32U4|ATmega16/32U2|ATmega32A|ATmega328/P|
+|-------------|-------------|----------|-------------|-------------|---------|-----------|
+|`B1`         |             |          |             |             |         |Timer 1    |
+|`B2`         |             |          |             |             |         |Timer 1    |
+|`B5`         |Timer 1      |          |Timer 1      |             |         |           |
+|`B6`         |Timer 1      |          |Timer 1      |             |         |           |
+|`B7`         |Timer 1      |Timer 1   |Timer 1      |Timer 1      |         |           |
+|`C4`         |Timer 3      |          |             |             |         |           |
+|`C5`         |Timer 3      |Timer 1   |             |Timer 1      |         |           |
+|`C6`         |Timer 3      |Timer 1   |Timer 3      |Timer 1      |         |           |
+|`D4`         |             |          |             |             |Timer 1  |           |
+|`D5`         |             |          |             |             |Timer 1  |           |
 
 All other pins will use timer-assisted software PWM:
 
diff --git a/docs/feature_macros.md b/docs/feature_macros.md
index 36fa761d2..aa1ebc337 100644
--- a/docs/feature_macros.md
+++ b/docs/feature_macros.md
@@ -4,7 +4,7 @@ Macros allow you to send multiple keystrokes when pressing just one key. QMK has
 
 !> **Security Note**: While it is possible to use macros to send passwords, credit card numbers, and other sensitive information it is a supremely bad idea to do so. Anyone who gets a hold of your keyboard will be able to access that information by opening a text editor.
 
-## The New Way: `SEND_STRING()` & `process_record_user`
+## `SEND_STRING()` & `process_record_user`
 
 Sometimes you want a key to type out words or phrases. For the most common situations, we've provided `SEND_STRING()`, which will type out a string (i.e. a sequence of characters) for you. All ASCII characters that are easily translatable to a keycode are supported (e.g. `qmk 123\n\t`).
 
@@ -262,15 +262,15 @@ This will clear all keys besides the mods currently pressed.
 This macro will register `KC_LALT` and tap `KC_TAB`, then wait for 1000ms. If the key is tapped again, it will send another `KC_TAB`; if there is no tap, `KC_LALT` will be unregistered, thus allowing you to cycle through windows.
 
 ```c
-bool is_alt_tab_active = false;    # ADD this near the begining of keymap.c
-uint16_t alt_tab_timer = 0;        # we will be using them soon.
+bool is_alt_tab_active = false; // ADD this near the begining of keymap.c
+uint16_t alt_tab_timer = 0;     // we will be using them soon.
 
-enum custom_keycodes {             # Make sure have the awesome keycode ready
+enum custom_keycodes {          // Make sure have the awesome keycode ready
   ALT_TAB = SAFE_RANGE,
 };
 
 bool process_record_user(uint16_t keycode, keyrecord_t *record) {
-  switch (keycode) {               # This will do most of the grunt work with the keycodes.
+  switch (keycode) { // This will do most of the grunt work with the keycodes.
     case ALT_TAB:
       if (record->event.pressed) {
         if (!is_alt_tab_active) {
@@ -287,7 +287,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
   return true;
 }
 
-void matrix_scan_user(void) {     # The very important timer.
+void matrix_scan_user(void) { // The very important timer.
   if (is_alt_tab_active) {
     if (timer_elapsed(alt_tab_timer) > 1000) {
       unregister_code(KC_LALT);
@@ -296,104 +296,3 @@ void matrix_scan_user(void) {     # The very important timer.
   }
 }
 ```
-
----
-
-##  **(DEPRECATED)** The Old Way: `MACRO()` & `action_get_macro`
-
-!> This is inherited from TMK, and hasn't been updated - it's recommended that you use `SEND_STRING` and `process_record_user` instead.
-
-By default QMK assumes you don't have any macros. To define your macros you create an `action_get_macro()` function. For example:
-
-```c
-const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt) {
-    if (record->event.pressed) {
-        switch(id) {
-            case 0:
-                return MACRO(D(LSFT), T(H), U(LSFT), T(I), D(LSFT), T(1), U(LSFT), END);
-            case 1:
-                return MACRO(D(LSFT), T(B), U(LSFT), T(Y), T(E), D(LSFT), T(1), U(LSFT), END);
-        }
-    }
-    return MACRO_NONE;
-};
-```
-
-This defines two macros which will be run when the key they are assigned to is pressed. If instead you'd like them to run when the key is released you can change the if statement:
-
-    if (!record->event.pressed) {
-
-### Macro Commands
-
-A macro can include the following commands:
-
-* I() change interval of stroke in milliseconds.
-* D() press key.
-* U() release key.
-* T() type key(press and release).
-* W() wait (milliseconds).
-* END end mark.
-
-### Mapping a Macro to a Key
-
-Use the `M()` function within your keymap to call a macro. For example, here is the keymap for a 2-key keyboard:
-
-```c
-const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
-    [0] = LAYOUT(
-        M(0), M(1)
-    ),
-};
-
-const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt) {
-    if (record->event.pressed) {
-        switch(id) {
-            case 0:
-                return MACRO(D(LSFT), T(H), U(LSFT), T(I), D(LSFT), T(1), U(LSFT), END);
-            case 1:
-                return MACRO(D(LSFT), T(B), U(LSFT), T(Y), T(E), D(LSFT), T(1), U(LSFT), END);
-        }
-    }
-    return MACRO_NONE;
-};
-```
-
-When you press the key on the left it will type "Hi!" and when you press the key on the right it will type "Bye!".
-
-### Naming Your Macros
-
-If you have a bunch of macros you want to refer to from your keymap while keeping the keymap easily readable you can name them using `#define` at the top of your file.
-
-```c
-#define M_HI M(0)
-#define M_BYE M(1)
-
-const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
-    [0] = LAYOUT(
-        M_HI, M_BYE
-    ),
-};
-```
-
-
-## Advanced Example:
-
-### Single-Key Copy/Paste
-
-This example defines a macro which sends `Ctrl-C` when pressed down, and `Ctrl-V` when released.
-
-```c
-const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt) {
-    switch(id) {
-        case 0: {
-            if (record->event.pressed) {
-                return MACRO( D(LCTL), T(C), U(LCTL), END  );
-            } else {
-                return MACRO( D(LCTL), T(V), U(LCTL), END  );
-            }
-            break;
-        }
-    }
-    return MACRO_NONE;
-};
-```
diff --git a/docs/feature_mouse_keys.md b/docs/feature_mouse_keys.md
index ffde13389..8e2a3a4cd 100644
--- a/docs/feature_mouse_keys.md
+++ b/docs/feature_mouse_keys.md
@@ -29,6 +29,9 @@ In your keymap you can use the following keycodes to map key presses to mouse ac
 |`KC_MS_BTN3`    |`KC_BTN3`|Press button 3   |
 |`KC_MS_BTN4`    |`KC_BTN4`|Press button 4   |
 |`KC_MS_BTN5`    |`KC_BTN5`|Press button 5   |
+|`KC_MS_BTN6`    |`KC_BTN6`|Press button 6   |
+|`KC_MS_BTN7`    |`KC_BTN7`|Press button 7   |
+|`KC_MS_BTN8`    |`KC_BTN8`|Press button 8   |
 |`KC_MS_WH_UP`   |`KC_WH_U`|Move wheel up    |
 |`KC_MS_WH_DOWN` |`KC_WH_D`|Move wheel down  |
 |`KC_MS_WH_LEFT` |`KC_WH_L`|Move wheel left  |
@@ -42,6 +45,7 @@ In your keymap you can use the following keycodes to map key presses to mouse ac
 Mouse keys supports three different modes to move the cursor:
 
 * **Accelerated (default):** Holding movement keys accelerates the cursor until it reaches its maximum speed.
+* **Kinetic:** Holding movement keys accelerates the cursor with its speed following a quadratic curve until it reaches its maximum speed.
 * **Constant:** Holding movement keys moves the cursor at constant speeds.
 * **Combined:** Holding movement keys accelerates the cursor until it reaches its maximum speed, but holding acceleration and movement keys simultaneously moves the cursor at constant speeds.
 
@@ -56,7 +60,8 @@ This is the default mode. You can adjust the cursor and scrolling acceleration u
 |Define                      |Default|Description                                              |
 |----------------------------|-------|---------------------------------------------------------|
 |`MOUSEKEY_DELAY`            |300    |Delay between pressing a movement key and cursor movement|
-|`MOUSEKEY_INTERVAL`         |50     |Time between cursor movements                            |
+|`MOUSEKEY_INTERVAL`         |50     |Time between cursor movements in milliseconds            |
+|`MOUSEKEY_MOVE_DELTA`       |5      |Step size                                                |
 |`MOUSEKEY_MAX_SPEED`        |10     |Maximum cursor speed at which acceleration stops         |
 |`MOUSEKEY_TIME_TO_MAX`      |20     |Time until maximum cursor speed is reached               |
 |`MOUSEKEY_WHEEL_DELAY`      |300    |Delay between pressing a wheel key and wheel movement    |
@@ -73,6 +78,30 @@ Tips:
 
 Cursor acceleration uses the same algorithm as the X Window System MouseKeysAccel feature. You can read more about it [on Wikipedia](https://en.wikipedia.org/wiki/Mouse_keys).
 
+### Kinetic Mode
+
+This is an extension of the accelerated mode. The kinetic mode uses a quadratic curve on the cursor speed which allows precise movements at the beginning and allows to cover large distances by increasing cursor speed quickly thereafter.  You can adjust the cursor and scrolling acceleration using the following settings in your keymap’s `config.h` file:
+
+|Define                                |Default  |Description                                                    |
+|--------------------------------------|---------|---------------------------------------------------------------|
+|`MK_KINETIC_SPEED`                    |undefined|Enable kinetic mode                                            |
+|`MOUSEKEY_DELAY`                      |8        |Delay between pressing a movement key and cursor movement      |
+|`MOUSEKEY_INTERVAL`                   |8        |Time between cursor movements in milliseconds                  |
+|`MOUSEKEY_MOVE_DELTA`                 |25       |Step size for accelerating from initial to base speed          |
+|`MOUSEKEY_INITIAL_SPEED`              |100      |Initial speed of the cursor in pixel per second                |
+|`MOUSEKEY_BASE_SPEED`                 |1000     |Maximum cursor speed at which acceleration stops               |
+|`MOUSEKEY_DECELERATED_SPEED`          |400      |Decelerated cursor speed                                       |
+|`MOUSEKEY_ACCELERATED_SPEED`          |3000     |Accelerated cursor speed                                       |
+|`MOUSEKEY_WHEEL_INITIAL_MOVEMENTS`    |16       |Initial number of movements of the mouse wheel                 |
+|`MOUSEKEY_WHEEL_BASE_MOVEMENTS`       |32       |Maximum number of movements at which acceleration stops        |
+|`MOUSEKEY_WHEEL_ACCELERATED_MOVEMENTS`|48       |Accelerated wheel movements                                    |
+|`MOUSEKEY_WHEEL_DECELERATED_MOVEMENTS`|8        |Decelerated wheel movements                                    |
+
+Tips:
+
+* The smoothness of the cursor movement depends on the `MOUSEKEY_INTERVAL` setting. The shorter the interval is set the smoother the movement will be.  Setting the value too low makes the cursor unresponsive.  Lower settings are possible if the micro processor is fast enough. For example: At an interval of `8` milliseconds, `125` movements per second will be initiated.  With a base speed of `1000` each movement will move the cursor by `8` pixels.
+* Mouse wheel movements are implemented differently from cursor movements. While it's okay for the cursor to move multiple pixels at once for the mouse wheel this would lead to jerky movements. Instead, the mouse wheel operates at step size `1`. Setting mouse wheel speed is done by adjusting the number of wheel movements per second.
+
 ### Constant mode
 
 In this mode you can define multiple different speeds for both the cursor and the mouse wheel. There is no acceleration. `KC_ACL0`, `KC_ACL1` and `KC_ACL2` change the cursor and scroll speed to their respective setting.
diff --git a/docs/feature_pointing_device.md b/docs/feature_pointing_device.md
index c9309d697..c6d3560f3 100644
--- a/docs/feature_pointing_device.md
+++ b/docs/feature_pointing_device.md
@@ -19,7 +19,7 @@ Keep in mind that a report_mouse_t (here "mouseReport") has the following proper
 * `mouseReport.y` - this is a signed int from -127 to 127 (not 128, this is defined in USB HID spec) representing movement (+ upward, - downward) on the y axis.
 * `mouseReport.v` - this is a signed int from -127 to 127 (not 128, this is defined in USB HID spec) representing vertical scrolling (+ upward, - downward).
 * `mouseReport.h` - this is a signed int from -127 to 127 (not 128, this is defined in USB HID spec) representing horizontal scrolling (+ right, - left).
-* `mouseReport.buttons` - this is a uint8_t in which the last 5 bits are used.  These bits represent the mouse button state - bit 3 is mouse button 5, and bit 7 is mouse button 1.
+* `mouseReport.buttons` - this is a uint8_t in which all 8 bits are used.  These bits represent the mouse button state - bit 0 is mouse button 1, and bit 7 is mouse button 8.
 
 Once you have made the necessary changes to the mouse report, you need to send it:
 
diff --git a/docs/feature_rgb_matrix.md b/docs/feature_rgb_matrix.md
index f5abd327c..fd866bd57 100644
--- a/docs/feature_rgb_matrix.md
+++ b/docs/feature_rgb_matrix.md
@@ -129,6 +129,28 @@ Configure the hardware via your `config.h`:
 
 ---
 
+### APA102 :id=apa102
+
+There is basic support for APA102 based addressable LED strands. To enable it, add this to your `rules.mk`:
+
+```makefile
+RGB_MATRIX_ENABLE = yes
+RGB_MATRIX_DRIVER = APA102
+```
+
+Configure the hardware via your `config.h`:
+
+```c
+// The pin connected to the data pin of the LEDs
+#define RGB_DI_PIN D7
+// The pin connected to the clock pin of the LEDs
+#define RGB_CI_PIN D6
+// The number of LEDs connected
+#define DRIVER_LED_TOTAL 70
+```
+
+---
+
 From this point forward the configuration is the same for all the drivers. The `led_config_t` struct provides a key electrical matrix to led index lookup table, what the physical position of each LED is on the board, and what type of key or usage the LED if the LED represents. Here is a brief example:
 
 ```c
diff --git a/docs/feature_rgblight.md b/docs/feature_rgblight.md
index 755fd769e..b5a2b179d 100644
--- a/docs/feature_rgblight.md
+++ b/docs/feature_rgblight.md
@@ -10,6 +10,7 @@ Currently QMK supports the following addressable LEDs (however, the white LED in
 
  * WS2811, WS2812, WS2812B, WS2812C, etc.
  * SK6812, SK6812MINI, SK6805
+ * APA102
 
 These LEDs are called "addressable" because instead of using a wire per color, each LED contains a small microchip that understands a special protocol sent over a single wire. The chip passes on the remaining data to the next LED, allowing them to be chained together. In this way, you can easily control the color of the individual LEDs.
 
@@ -21,11 +22,19 @@ On keyboards with onboard RGB LEDs, it is usually enabled by default. If it is n
 RGBLIGHT_ENABLE = yes
 ```
 
-At minimum you must define the data pin your LED strip is connected to, and the number of LEDs in the strip, in your `config.h`. If your keyboard has onboard RGB LEDs, and you are simply creating a keymap, you usually won't need to modify these.
+For APA102 LEDs, add the following to your `rules.mk`:
+
+```make
+RGBLIGHT_ENABLE = yes
+RGBLIGHT_DRIVER = APA102
+```
+
+At minimum you must define the data pin your LED strip is connected to, and the number of LEDs in the strip, in your `config.h`. For APA102 LEDs, you must also define the clock pin. If your keyboard has onboard RGB LEDs, and you are simply creating a keymap, you usually won't need to modify these.
 
 |Define         |Description                                                                                              |
 |---------------|---------------------------------------------------------------------------------------------------------|
 |`RGB_DI_PIN`   |The pin connected to the data pin of the LEDs                                                            |
+|`RGB_CI_PIN`   |The pin connected to the clock pin of the LEDs (APA102 only)                                             |
 |`RGBLED_NUM`   |The number of LEDs connected                                                                             |
 |`RGBLED_SPLIT` |(Optional) For split keyboards, the number of LEDs connected on each half directly wired to `RGB_DI_PIN` |
 
@@ -139,7 +148,7 @@ The following options are used to tweak the various animations:
 |`RGBLIGHT_EFFECT_KNIGHT_OFFSET`     |`0`          |The number of LEDs to start the "Knight" animation from the start of the strip by              |
 |`RGBLIGHT_RAINBOW_SWIRL_RANGE`      |`255`        |Range adjustment for the rainbow swirl effect to get different swirls                          |
 |`RGBLIGHT_EFFECT_SNAKE_LENGTH`      |`4`          |The number of LEDs to light up for the "Snake" animation                                       |
-|`RGBLIGHT_EFFECT_TWINKLE_LIFE`      |`75`         |Adjusts how quickly each LED brightens and dims when twinkling (in animation steps)            |
+|`RGBLIGHT_EFFECT_TWINKLE_LIFE`      |`200`        |Adjusts how quickly each LED brightens and dims when twinkling (in animation steps)            |
 |`RGBLIGHT_EFFECT_TWINKLE_PROBABILITY`|`1/127`     |Adjusts how likely each LED is to twinkle (on each animation step)                             |
 
 ### Example Usage to Reduce Memory Footprint
diff --git a/docs/feature_split_keyboard.md b/docs/feature_split_keyboard.md
index b23411420..c285e353d 100644
--- a/docs/feature_split_keyboard.md
+++ b/docs/feature_split_keyboard.md
@@ -181,6 +181,16 @@ If you're having issues with serial communication, you can change this value, as
 * **`4`**: about 26kbps
 * **`5`**: about 20kbps
 
+```c
+#define SPLIT_MODS_ENABLE
+```
+
+This enables transmitting modifier state (normal, weak and oneshot) to the non
+primary side of the split keyboard.  This adds a few bytes of data to the split
+communication protocol and may impact the matrix scan speed when enabled.
+The purpose of this feature is to support cosmetic use of modifer state (e.g.
+displaying status on an OLED screen).
+
 ###  Hardware Configuration Options
 
 There are some settings that you may need to configure, based on how the hardware is set up. 
diff --git a/docs/ja/compatible_microcontrollers.md b/docs/ja/compatible_microcontrollers.md
index 48b07aaec..31d362d09 100644
--- a/docs/ja/compatible_microcontrollers.md
+++ b/docs/ja/compatible_microcontrollers.md
@@ -14,6 +14,7 @@ QMK ��分�容��フラッシュメモリを備�� USB 対応 AVR �
 * [ATmega16U2](https://www.microchip.com/wwwproducts/en/ATmega16U2) / [ATmega32U2](https://www.microchip.com/wwwproducts/en/ATmega32U2)
 * [ATmega16U4](https://www.microchip.com/wwwproducts/en/ATmega16U4) / [ATmega32U4](https://www.microchip.com/wwwproducts/en/ATmega32U4)
 * [AT90USB64](https://www.microchip.com/wwwproducts/en/AT90USB646) / [AT90USB128](https://www.microchip.com/wwwproducts/en/AT90USB1286)
+* [AT90USB162](https://www.microchip.com/wwwproducts/en/AT90USB162)
 
 組�込�� USB インターフェースを���������� MCU �代�り� [V-USB](https://www.obdev.at/products/vusb/index.html) を使���:
 
diff --git a/docs/ja/feature_macros.md b/docs/ja/feature_macros.md
index 14a58ad24..c42a61b5f 100644
--- a/docs/ja/feature_macros.md
+++ b/docs/ja/feature_macros.md
@@ -9,7 +9,7 @@
 
 !> **セキュリティ�注�**: マクロを使���パスワード�クレジットカード番����他�機密情報���れも�信�る����能�����れ��常�悪�考���。����キーボードを手�入れ�人�誰�もテキストエディタを開����情報�アクセス�る�������。
 
-## 新��方法: `SEND_STRING()` � `process_record_user`
+## `SEND_STRING()` � `process_record_user`
 
 �語���フレーズを入力�るキー�欲��時��り��。最も一般的�状����� `SEND_STRING()` を�供�����。�れ�文字列(��り�文字�シーケンス)を入力���。簡��キーコード�変��る�����る全�� ASCII 文字�サ�ート�れ���� (例���`qmk 123\n\t`)。
 
@@ -267,15 +267,15 @@ SEND_STRING(".."SS_TAP(X_END));
 ��マクロ� `KC_LALT` を登録��`KC_TAB` をタップ���1000ms 待���。キー��度タップ�れる��別� `KC_TAB` ��信�れ��; タップ�無�場��`KC_LALT` �登録解除�れ�ウィンドウを切り替�る�������。
 
 ```c
-bool is_alt_tab_active = false;    # keymap.c �先頭付近��れを追加���
-uint16_t alt_tab_timer = 0;        # ����れらを使���
+bool is_alt_tab_active = false; // keymap.c �先頭付近��れを追加���
+uint16_t alt_tab_timer = 0;     // ����れらを使���
 
-enum custom_keycodes {             # 素晴ら��キーコードを用�������
+enum custom_keycodes {          // 素晴ら��キーコードを用�������
   ALT_TAB = SAFE_RANGE,
 };
 
 bool process_record_user(uint16_t keycode, keyrecord_t *record) {
-  switch (keycode) {               # �れ�キーコードを利用����ら��作業���ん�を行���。
+  switch (keycode) { // �れ�キーコードを利用����ら��作業���ん�を行���。
     case ALT_TAB:
       if (record->event.pressed) {
         if (!is_alt_tab_active) {
@@ -292,7 +292,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
   return true;
 }
 
-void matrix_scan_user(void) {     # ��も���タイマー
+void matrix_scan_user(void) { // ��も���タイマー
   if (is_alt_tab_active) {
     if (timer_elapsed(alt_tab_timer) > 1000) {
       unregister_code(KC_LALT);
@@ -301,104 +301,3 @@ void matrix_scan_user(void) {     # ��も���タイマー
   }
 }
 ```
-
----
-
-## **(�推奨)** ��方法: `MACRO()` � `action_get_macro`
-
-!> �れ� TMK �ら継承�れ��り�更新�れ����ん - 代�り� `SEND_STRING` � `process_record_user` を使���を�勧����。
-
-デフォルト���QMK �マクロ�無���を��������。マクロを定義�る���`action_get_macro()` 関数を作����。例��:
-
-```c
-const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt) {
-    if (record->event.pressed) {
-        switch(id) {
-            case 0:
-                return MACRO(D(LSFT), T(H), U(LSFT), T(I), D(LSFT), T(1), U(LSFT), END);
-            case 1:
-                return MACRO(D(LSFT), T(B), U(LSFT), T(Y), T(E), D(LSFT), T(1), U(LSFT), END);
-        }
-    }
-    return MACRO_NONE;
-};
-```
-
-�れ�割り当�られ��るキー�押�れ�時�実行�れる2��マクロを定義���。キー�放�れ�時��れらを実行���場���if 文を変更�る�������。
-
-    if (!record->event.pressed) {
-
-### マクロコマンド
-
-マクロ�以下�コマンドを��る�������:
-
-* I() �ストローク�間隔をミリ秒���変更���。
-* D() �キーを押���。
-* U() �キーを放���。
-* T() �キーをタイプ(押��放�)���。
-* W() �待��� (ミリ秒)。
-* END 終了マーク。
-
-### マクロをキー�マッピング�る
-
-マクロを呼�出���キーマップ内� `M()` 関数を使���。例���2キー�キーボード�キーマップ�以下�通り��:
-
-```c
-const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
-    [0] = LAYOUT(
-        M(0), M(1)
-    ),
-};
-
-const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt) {
-    if (record->event.pressed) {
-        switch(id) {
-            case 0:
-                return MACRO(D(LSFT), T(H), U(LSFT), T(I), D(LSFT), T(1), U(LSFT), END);
-            case 1:
-                return MACRO(D(LSFT), T(B), U(LSFT), T(Y), T(E), D(LSFT), T(1), U(LSFT), END);
-        }
-    }
-    return MACRO_NONE;
-};
-```
-
-左��キーを押���"Hi!" を入力�����キーを押�� "Bye!" を入力���。
-
-### マクロ���を付�る
-
-キーマップを読�や�����らキーマップ�ら�照���マクロ����ん�る場���ファイル�先頭� `#define` を使����を付�る�������。
-
-```c
-#define M_HI M(0)
-#define M_BYE M(1)
-
-const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
-    [0] = LAYOUT(
-        M_HI, M_BYE
-    ),
-};
-```
-
-
-## 高度�例:
-
-### �一キー�コピー�貼り付�
-
-��例��押�れ�時� `Ctrl-C` を�信��放�れる時� `Ctrl-V` を�信�るマクロを定義���。
-
-```c
-const macro_t *action_get_macro(keyrecord_t *record, uint8_t id, uint8_t opt) {
-    switch(id) {
-        case 0: {
-            if (record->event.pressed) {
-                return MACRO( D(LCTL), T(C), U(LCTL), END  );
-            } else {
-                return MACRO( D(LCTL), T(V), U(LCTL), END  );
-            }
-            break;
-        }
-    }
-    return MACRO_NONE;
-};
-```
diff --git a/docs/ja/feature_mouse_keys.md b/docs/ja/feature_mouse_keys.md
index 74b09e939..e4fa9dfb4 100644
--- a/docs/ja/feature_mouse_keys.md
+++ b/docs/ja/feature_mouse_keys.md
@@ -34,6 +34,9 @@ MOUSEKEY_ENABLE = yes
 | `KC_MS_BTN3` | `KC_BTN3` | ボタン3を押� |
 | `KC_MS_BTN4` | `KC_BTN4` | ボタン4を押� |
 | `KC_MS_BTN5` | `KC_BTN5` | ボタン5を押� |
+| `KC_MS_BTN6` | `KC_BTN6` | ボタン6を押� |
+| `KC_MS_BTN7` | `KC_BTN7` | ボタン7を押� |
+| `KC_MS_BTN8` | `KC_BTN8` | ボタン8を押� |
 | `KC_MS_WH_UP` | `KC_WH_U` | ホイールを�����回転 |
 | `KC_MS_WH_DOWN` | `KC_WH_D` | ホイールを手���回転 |
 | `KC_MS_WH_LEFT` | `KC_WH_L` | ホイールを左�倒� |
diff --git a/docs/ja/proton_c_conversion.md b/docs/ja/proton_c_conversion.md
index 6e4f7dcb6..e7c07413c 100644
--- a/docs/ja/proton_c_conversion.md
+++ b/docs/ja/proton_c_conversion.md
@@ -51,6 +51,7 @@ Proton C ã�«ã�¯1ã�¤ã�®ã‚ªãƒ³ãƒœãƒ¼ãƒ‰ LED(C13)ã�—ã�‹ã�ªã��ã€�デフォルトã�§ã
 
 ```
 MCU = STM32F303
+BOARD = QMK_PROTON_C
 ```
 
 次�変数�存在�る場��削除���。
diff --git a/docs/proton_c_conversion.md b/docs/proton_c_conversion.md
index 1b5e496e7..47511e1b1 100644
--- a/docs/proton_c_conversion.md
+++ b/docs/proton_c_conversion.md
@@ -44,6 +44,7 @@ To use the Proton C natively, without having to specify `CTPC=yes`, you need to
 
 ```
 MCU = STM32F303
+BOARD = QMK_PROTON_C
 ```
 
 Remove these variables if they exist:
diff --git a/docs/reference_info_json.md b/docs/reference_info_json.md
index 67c189d78..30d813e93 100644
--- a/docs/reference_info_json.md
+++ b/docs/reference_info_json.md
@@ -19,8 +19,20 @@ The `info.json` file is a JSON formatted dictionary with the following keys avai
   * Width of the board in Key Units
 * `height`
   * Height of the board in Key Units
+* `debounce`
+  * How many milliseconds (ms) to wait for debounce to happen. (Default: 5)
+* `diode_direction`
+  * The direction diodes face. See [`DIRECT_PINS` in the hardware configuration](https://docs.qmk.fm/#/config_options?id=hardware-options) for more details.
+* `layout_aliases`
+  * A dictionary containing layout aliases. The key is the alias and the value is a layout in `layouts` it maps to.
 * `layouts`
-  * Physical Layout representations. See the next section for more detail.
+  * Physical Layout representations. See the [Layout Format](#layout_format) section for more detail.
+* `matrix_pins`
+  * Configure the pins corresponding to columns and rows, or direct pins. See [Matrix Pins](#matrix_pins) for more detail.
+* `rgblight`
+  * Configure the [RGB Lighting feature](feature_rgblight.md). See the [RGB Lighting](#rgb_lighting) section for more detail.
+* `usb`
+  * Configure USB VID, PID, and other parameters. See [USB](#USB) for more detail.
 
 ### Layout Format
 
@@ -49,25 +61,129 @@ All key positions and rotations are specified in relation to the top-left corner
   * The width of the key, in Key Units. Ignored if `ks` is provided. Default: `1`
 * `h`
   * The height of the key, in Key Units. Ignored if `ks` is provided. Default: `1`
-* `r`
-  * How many degrees clockwise to rotate the key.
-* `rx`
-  * The absolute position of the point to rotate the key around in the horizontal axis. Default: `x`
-* `ry`
-  * The absolute position of the point to rotate the key around in the vertical axis. Default: `y`
-* `ks`
-  * Key Shape: define a polygon by providing a list of points, in Key Units.
-  * **Important**: These are relative to the top-left of the key, not absolute.
-  * Example ISO Enter: `[ [0,0], [1.5,0], [1.5,2], [0.25,2], [0.25,1], [0,1], [0,0] ]`
 * `label`
   * What to name this position in the matrix.
-  * This should usually be the same name as what is silkscreened on the PCB at this location.
-
-## How is the Metadata Exposed?
-
-This metadata is primarily used in two ways:
-
-* To allow web-based configurators to dynamically generate UI
-* To support the new `make keyboard:keymap:qmk` target, which bundles this metadata up with the firmware to allow QMK Toolbox to be smarter.
-
-Configurator authors can see the [QMK Compiler](https://docs.api.qmk.fm/using-the-api) docs for more information on using the JSON API.
+  * This should usually correspond to the keycode for the first layer of the default keymap.
+* `matrix`
+  * A 2 item list describing the row and column location for this key.
+
+### Matrix Pins
+
+Currently QMK supports connecting switches either directly to GPIO pins or via a switch matrix. At this time you can not combine these, they are mutually exclusive.
+
+#### Switch Matrix
+
+Most keyboards use a switch matrix to connect keyswitches to the MCU. You can define your pin columns and rows to configure your switch matrix. When defining switch matrices you should also define your `diode_direction`.
+
+Example:
+
+```json
+{
+  "diode_direction": "COL2ROW",
+  "matrix_pins": {
+    "cols": ["F4", "E6", "B1", "D2"],
+    "rows": ["B0", "D3", "D5", "D4", "D6"]
+  }
+}
+```
+
+#### Direct Pins
+
+Direct pins are when you connect one side of the switch to GND and the other side to a GPIO pin on your MCU. No diode is required, but there is a 1:1 mapping between switches and pins.
+
+When specifying direct pins you need to arrange them in nested arrays. The outer array consists of rows, while the inner array is a text string corresponding to a pin. You can use `null` to indicate an empty spot in the matrix.
+
+Example:
+
+```json
+{
+    "matrix_pins": {
+        "direct": [
+            ["A10", "A9"],
+            ["A0", "B8"],
+            [null, "B11"],
+            ["B9", "A8"],
+            ["A7", "B1"],
+            [null, "B2"]
+        ]
+    }
+}
+```
+
+### RGB Lighting
+
+This section controls the legacy WS2812 support in QMK. This should not be confused with the RGB Matrix feature, which can be used to control both WS2812 and ISSI RGB LEDs.
+
+The following items can be set. Not every value is required.
+
+* `led_count`
+    * The number of LEDs in your strip
+* `pin`
+    * The GPIO pin that your LED strip is connected to
+* `animations`
+    * A dictionary that lists enabled and disabled animations. See [RGB Light Animations](#rgb_light_animations) below.
+* `sleep`
+    * Set to `true` to enable lighting during host sleep
+* `split`
+    * Set to `true` to enable synchronization functionality between split halves
+* `split_count`
+    * For split keyboards, the number of LEDs on each side
+* `max_brightness`
+    * (0-255) What the maxmimum brightness (value) level is
+* `hue_steps`
+    * How many steps of adjustment to have for hue
+* `saturation_steps`
+    * How many steps of adjustment to have for saturation
+* `brightness_steps`
+    * How many steps of adjustment to have for brightness (value)
+
+Example:
+
+```json
+{
+    "rgblight": {
+        "led_count": 4,
+        "pin": "F6",
+        "hue_steps": 10,
+        "saturation_steps": 17,
+        "brightness_steps": 17,
+        "animations": {
+            "all": true
+        }
+    }
+}
+```
+
+#### RGB Light Animations
+
+The following animations can be enabled:
+
+| Key | Description |
+|-----|-------------|
+| `all` | Enable all additional animation modes. |
+| `alternating` | Enable alternating animation mode. |
+| `breathing` | Enable breathing animation mode. |
+| `christmas` | Enable christmas animation mode. |
+| `knight` | Enable knight animation mode. |
+| `rainbow_mood` | Enable rainbow mood animation mode. |
+| `rainbow_swirl` | Enable rainbow swirl animation mode. |
+| `rgb_test` | Enable RGB test animation mode. |
+| `snake` | Enable snake animation mode. |
+| `static_gradient` | Enable static gradient mode. |
+| `twinkle` | Enable twinkle animation mode. |
+
+### USB
+
+Every USB keyboard needs to have its USB parmaters defined. At a minimum you need to set vid, pid, and device version.
+
+Example:
+
+```json
+{
+  "usb": {
+    "vid": "0xC1ED",
+    "pid": "0x23B0",
+    "device_ver": "0x0001"
+  }
+}
+```
diff --git a/docs/reference_keymap_extras.md b/docs/reference_keymap_extras.md
index f2abb4e59..40a195684 100644
--- a/docs/reference_keymap_extras.md
+++ b/docs/reference_keymap_extras.md
@@ -18,7 +18,9 @@ To use these, simply `#include` the corresponding [header file](https://github.c
 |Dutch (Belgium)            |`keymap_belgian.h`              |
 |English (Ireland)          |`keymap_irish.h`                |
 |English (UK)               |`keymap_uk.h`                   |
+|English (US Extended)      |`keymap_us_extended.h`          |
 |English (US International) |`keymap_us_international.h`     |
+|English (US International, Linux)|`keymap_us_international_linux.h`|
 |Estonian                   |`keymap_estonian.h`             |
 |Finnish                    |`keymap_finnish.h`              |
 |French                     |`keymap_french.h`               |
diff --git a/docs/serial_driver.md b/docs/serial_driver.md
index bc376b6dd..c98f4c117 100644
--- a/docs/serial_driver.md
+++ b/docs/serial_driver.md
@@ -60,6 +60,7 @@ Configure the hardware via your config.h:
                                    //  5: about 19200 baud
 #define SERIAL_USART_DRIVER SD1 // USART driver of TX pin. default: SD1
 #define SERIAL_USART_TX_PAL_MODE 7 // Pin "alternate function", see the respective datasheet for the appropriate values for your MCU. default: 7
+#define SERIAL_USART_TIMEOUT 100 // USART driver timeout. default 100
 ```
 
 You must also enable the ChibiOS `SERIAL` feature:
diff --git a/docs/spi_driver.md b/docs/spi_driver.md
index 1d432432a..03c008da2 100644
--- a/docs/spi_driver.md
+++ b/docs/spi_driver.md
@@ -6,12 +6,12 @@ The SPI Master drivers used in QMK have a set of common functions to allow porta
 
 No special setup is required - just connect the `SS`, `SCK`, `MOSI` and `MISO` pins of your SPI devices to the matching pins on the MCU:
 
-|MCU            |`SS`|`SCK`|`MOSI`|`MISO`|
-|---------------|----|-----|------|------|
-|ATMega16/32U2/4|`B0`|`B1` |`B2`  |`B3`  |
-|AT90USB64/128  |`B0`|`B1` |`B2`  |`B3`  |
-|ATmega32A      |`B4`|`B7` |`B5`  |`B6`  |
-|ATmega328/P    |`B2`|`B5` |`B3`  |`B4`  |
+|MCU              |`SS`|`SCK`|`MOSI`|`MISO`|
+|-----------------|----|-----|------|------|
+|ATMega16/32U2/4  |`B0`|`B1` |`B2`  |`B3`  |
+|AT90USB64/128/162|`B0`|`B1` |`B2`  |`B3`  |
+|ATmega32A        |`B4`|`B7` |`B5`  |`B6`  |
+|ATmega328/P      |`B2`|`B5` |`B3`  |`B4`  |
 
 You may use more than one slave select pin, not just the `SS` pin. This is useful when you have multiple devices connected and need to communicate with them individually.
 `SPI_SS_PIN` can be passed to `spi_start()` to refer to `SS`.
diff --git a/docs/uart_driver.md b/docs/uart_driver.md
new file mode 100644
index 000000000..4d1716975
--- /dev/null
+++ b/docs/uart_driver.md
@@ -0,0 +1,90 @@
+# UART Driver
+
+The UART drivers used in QMK have a set of common functions to allow portability between MCUs.
+
+Currently, this driver does not support enabling hardware flow control (the `RTS` and `CTS` pins) if available, but may do so in future.
+
+## AVR Configuration
+
+No special setup is required - just connect the `RX` and `TX` pins of your UART device to the opposite pins on the MCU:
+
+|MCU          |`TX`|`RX`|`CTS`|`RTS`|
+|-------------|----|----|-----|-----|
+|ATmega16/32U2|`D3`|`D2`|`D7` |`D6` |
+|ATmega16/32U4|`D3`|`D2`|`D5` |`B7` |
+|AT90USB64/128|`D3`|`D2`|*n/a*|*n/a*|
+|ATmega32A    |`D1`|`D0`|*n/a*|*n/a*|
+|ATmega328/P  |`D1`|`D0`|*n/a*|*n/a*|
+
+## ChibiOS/ARM Configuration
+
+You'll need to determine which pins can be used for UART -- as an example, STM32 parts generally have multiple UART peripherals, labeled USART1, USART2, USART3 etc.
+
+To enable UART, modify your board's `halconf.h` to enable the serial driver:
+
+```c
+#define HAL_USE_SERIAL TRUE
+```
+
+Then, modify your board's `mcuconf.h` to enable the peripheral you've chosen, for example:
+
+```c
+#undef STM32_SERIAL_USE_USART2
+#define STM32_SERIAL_USE_USART2 TRUE
+```
+
+Configuration-wise, you'll need to set up the peripheral as per your MCU's datasheet -- the defaults match the pins for a Proton-C, i.e. STM32F303.
+
+|`config.h` override       |Description                                                    |Default Value|
+|--------------------------|---------------------------------------------------------------|-------------|
+|`#define SERIAL_DRIVER`   |USART peripheral to use - USART1 -> `SD1`, USART2 -> `SD2` etc.|`SD1`        |
+|`#define SD1_TX_PIN`      |The pin to use for TX                                          |`A9`         |
+|`#define SD1_TX_PAL_MODE` |The alternate function mode for TX                             |`7`          |
+|`#define SD1_RX_PIN`      |The pin to use for RX                                          |`A10`        |
+|`#define SD1_RX_PAL_MODE` |The alternate function mode for RX                             |`7`          |
+|`#define SD1_CTS_PIN`     |The pin to use for CTS                                         |`A11`        |
+|`#define SD1_CTS_PAL_MODE`|The alternate function mode for CTS                            |`7`          |
+|`#define SD1_RTS_PIN`     |The pin to use for RTS                                         |`A12`        |
+|`#define SD1_RTS_PAL_MODE`|The alternate function mode for RTS                            |`7`          |
+
+## Functions
+
+### `void uart_init(uint32_t baud)`
+
+Initialize the UART driver. This function must be called only once, before any of the below functions can be called.
+
+#### Arguments
+
+ - `uint32_t baud`  
+   The baud rate to transmit and receive at. This may depend on the device you are communicating with. Common values are 1200, 2400, 4800, 9600, 19200, 38400, 57600, and 115200.
+
+---
+
+### `void uart_putchar(uint8_t c)`
+
+Transmit a single byte.
+
+#### Arguments
+
+ - `uint8_t c`  
+   The byte (character) to send, from 0 to 255.
+
+---
+
+### `uint8_t uart_getchar(void)`
+
+Receive a single byte.
+
+#### Return Value
+
+The byte read from the receive buffer.
+
+---
+
+### `bool uart_available(void)`
+
+Return whether the receive buffer contains data. Call this function to determine if `uart_getchar()` will return meaningful data.
+
+#### Return Value
+
+`true` if the receive buffer length is non-zero.