2020 February 29 Breaking Changes Update (#8064)

3 files changed, 125 insertions, 22 deletions

diff --git a/docs/ChangeLog/20200229.md b/docs/ChangeLog/20200229.md
new file mode 100644
index 000000000..398fe01c0
--- /dev/null
+++ b/docs/ChangeLog/20200229.md
@@ -0,0 +1,75 @@
+# QMK Breaking Change - 2020 Feb 29 Changelog
+
+Four times a year QMK runs a process for merging Breaking Changes. A Breaking Change is any change which modifies how QMK behaves in a way that is incompatible or potentially dangerous. We limit these changes to 4 times per year so that users can have confidence that updating their QMK tree will not break their keymaps.
+
+
+## Update ChibiOS/ChibiOS-Contrib/uGFX submodules
+
+* General Notes
+    * A `make git-submodule` may be required after pulling the latest QMK firmware code to update affected submodules to the upgraded revisions
+    * Enabling link-time-optimization (`LINK_TIME_OPTIMIZATION_ENABLE = yes`) should work on a lot more boards
+* Upgrade to ChibiOS ver19.1.3
+    * This will allow QMK to update to upstream ChibiOS a lot easier -- the old version was ~2 years out of date. Automated update scripts have been made available to simplify future upgrades.
+    * Includes improved MCU support and bugfixes
+    * ChibiOS revision is now included in Command output
+    * Timers should now be more accurate
+* Upgrade to newer ChibiOS-Contrib
+    * Also includes improved MCU support and bugfixes
+    * ChibiOS-Contrib revision is now included in Command output
+* Upgrade to newer uGFX
+    * Required in order to support updated ChibiOS
+
+
+## Fix ChibiOS timer overflow for 16-bit SysTick devices
+
+* On 16-bit SysTick devices, the timer subsystem in QMK was incorrectly dealing with overflow.
+    * When running at a 100000 SysTick frequency (possible on 16-bit devices, but uncommon), this overflow would occur after 0.65 seconds.
+* Timers are now correctly handling this overflow case and timing should now be correct on ChibiOS/ARM.
+
+
+## Update LUFA submodule
+
+* Updates the LUFA submodule to include updates from upstream (abcminiuser/lufa)
+* Includes some cleanup for QMK DFU generation
+
+
+## Encoder flip
+
+* Flips the encoder direction so that `clockwise == true` is for actually turning the knob clockwise
+* Adds `ENCODER_DIRECTION_FLIP` define, so that reversing the expected dirction is simple for users.
+* Cleans up documentation page for encoders
+
+
+## Adding support for `BACKLIGHT_ON_STATE` for hardware PWM backlight
+
+* Previously, the define only affected software PWM, and hardware PWM always assumed an N-channel MOSFET.
+* The hardware PWM backlight setup has been updated to respect this option.
+* The default "on" state has been changed to `1` - **this impacts all keyboards using software PWM backlight that do not define it explicitly**. If your keyboard's backlight is acting strange, it may have a P-channel MOSFET, and will need to have `#define BACKLIGHT_ON_STATE 0` added to the keyboard-level `config.h`. Please see the PR for more detailed information.
+
+
+## Migrating `ACTION_LAYER_TAP_KEY()` entries in `fn_actions` to `LT()` keycodes
+
+* `fn_actions` is deprecated, and its functionality has been superseded by direct keycodes and `process_record_user()`
+* The end result of removing this obsolete feature should result in a decent reduction in firmware size and code complexity
+* All keymaps affected are recommended to switch away from `fn_actions` in favour of the [custom keycode](https://docs.qmk.fm/#/custom_quantum_functions) and [macro](https://docs.qmk.fm/#/feature_macros) features
+
+
+## Moving backlight keycode handling to `process_keycode/`
+
+* This refactors the backlight keycode logic to be clearer and more modular.
+* All backlight-related keycodes are now actioned in a single file.
+* The `ACTION_BACKLIGHT_*` macros have also been deleted. If you are still using these in a `fn_actions[]` block, please switch to using the backlight keycodes or functions directly.
+
+
+## Refactor Planck keymaps to use Layout Macros
+
+* Refactor Planck keymaps to use layout macros instead of raw matrix assignments
+* Makes keymaps revision-agnostic
+* Should reduce noise and errors in Travis CI logs
+
+
+## GON NerD codebase refactor
+
+* Splits the codebase for GON NerD 60 and NerdD TKL PCBs into two separate directories.
+* If your keymap is for a NerD 60 PCB, your `make` command is now `make gon/nerd60:<keymap>`.
+* If your keymap is for a NerD TKL PCB, your `make` command is now `make gon/nerdtkl:<keymap>`.
diff --git a/docs/feature_backlight.md b/docs/feature_backlight.md
index e74aab1e3..7c68d74e1 100644
--- a/docs/feature_backlight.md
+++ b/docs/feature_backlight.md
@@ -119,10 +119,22 @@ When both timers are in use for Audio, the backlight PWM will not use a hardware
 
 To change the behavior of the backlighting, `#define` these in your `config.h`:
 
-|Define               |Default      |Description                                                                                                   |
-|---------------------|-------------|--------------------------------------------------------------------------------------------------------------|
-|`BACKLIGHT_PIN`      |`B7`         |The pin that controls the LEDs. Unless you are designing your own keyboard, you shouldn't need to change this |
-|`BACKLIGHT_PINS`     |*Not defined*|experimental: see below for more information                                                                  |
+|Define               |Default      |Description                                                                                                  |
+|---------------------|-------------|-------------------------------------------------------------------------------------------------------------|
+|`BACKLIGHT_PIN`      |`B7`         |The pin that controls the LEDs. Unless you are designing your own keyboard, you shouldn't need to change this|
+|`BACKLIGHT_PINS`     |*Not defined*|experimental: see below for more information                                                                 |
+|`BACKLIGHT_LEVELS`   |`3`          |The number of brightness levels (maximum 31 excluding off)                                                   |
+|`BACKLIGHT_CAPS_LOCK`|*Not defined*|Enable Caps Lock indicator using backlight (for keyboards without dedicated LED)                             |
+|`BACKLIGHT_BREATHING`|*Not defined*|Enable backlight breathing, if supported                                                                     |
+|`BREATHING_PERIOD`   |`6`          |The length of one backlight "breath" in seconds                                                              |
+|`BACKLIGHT_ON_STATE` |`1`          |The state of the backlight pin when the backlight is "on" - `1` for high, `0` for low                        |
+
+### Backlight On State
+
+Most backlight circuits are driven by an N-channel MOSFET or NPN transistor. This means that to turn the transistor *on* and light the LEDs, you must drive the backlight pin, connected to the gate or base, *high*.
+Sometimes, however, a P-channel MOSFET, or a PNP transistor is used. In this case, when the transistor is on, the pin is driven *low* instead.
+
+This functionality is configured at the keyboard level with the `BACKLIGHT_ON_STATE` define.
 
 ### Multiple backlight pins
 
diff --git a/docs/feature_encoders.md b/docs/feature_encoders.md
index cbf72914e..4a0ae60c3 100644
--- a/docs/feature_encoders.md
+++ b/docs/feature_encoders.md
@@ -2,23 +2,35 @@
 
 Basic encoders are supported by adding this to your `rules.mk`:
 
-    ENCODER_ENABLE = yes
+```make
+ENCODER_ENABLE = yes
+```
 
 and this to your `config.h`:
 
-    #define ENCODERS_PAD_A { B12 }
-    #define ENCODERS_PAD_B { B13 }
+```c
+#define ENCODERS_PAD_A { B12 }
+#define ENCODERS_PAD_B { B13 }
+```
 
 Each PAD_A/B variable defines an array so multiple encoders can be defined, e.g.:
 
-    #define ENCODERS_PAD_A { encoder1a, encoder2a }
-    #define ENCODERS_PAD_B { encoder1b, encoder2b }
+```c
+#define ENCODERS_PAD_A { encoder1a, encoder2a }
+#define ENCODERS_PAD_B { encoder1b, encoder2b }
+```
+
+If your encoder's clockwise directions are incorrect, you can swap the A & B pad definitions.  They can also be flipped with a define:
 
-If your encoder's clockwise directions are incorrect, you can swap the A & B pad definitions.
+```c
+#define ENCODER_DIRECTION_FLIP
+```
 
 Additionally, the resolution can be specified in the same file (the default & suggested is 4):
 
-    #define ENCODER_RESOLUTION 4
+```c
+#define ENCODER_RESOLUTION 4
+```
 
 ## Split Keyboards
 
@@ -33,27 +45,31 @@ If you are using different pinouts for the encoders on each half of a split keyb
 
 The callback functions can be inserted into your `<keyboard>.c`:
 
-    void encoder_update_kb(uint8_t index, bool clockwise) {
-        encoder_update_user(index, clockwise);
-    }
+```c
+void encoder_update_kb(uint8_t index, bool clockwise) {
+    encoder_update_user(index, clockwise);
+}
+```
 
 or `keymap.c`:
 
-    void encoder_update_user(uint8_t index, bool clockwise) {
-      if (index == 0) { /* First encoder */
+```c
+void encoder_update_user(uint8_t index, bool clockwise) {
+    if (index == 0) { /* First encoder */
         if (clockwise) {
-          tap_code(KC_PGDN);
+            tap_code(KC_PGDN);
         } else {
-          tap_code(KC_PGUP);
+            tap_code(KC_PGUP);
         }
-      } else if (index == 1) { /* Second encoder */  
+        } else if (index == 1) { /* Second encoder */  
         if (clockwise) {
-          tap_code(KC_UP);
+            tap_code(KC_DOWN);
         } else {
-          tap_code(KC_DOWN);
+            tap_code(KC_UP);
         }
-      }
     }
+}
+```
 
 ## Hardware