1 files changed, 25 insertions, 5 deletions

diff --git a/readme.md b/readme.md
index cd65e0e69..afdb03ba5 100644
--- a/readme.md
+++ b/readme.md
@@ -348,6 +348,10 @@ This allows you output audio on the C6 pin (needs abstracting). See the [audio s
 
 Use this to debug changes to variable values, see the [tracing variables](#tracing-variables) section for more information.
 
+`API_SYSEX_ENABLE`
+
+This enables using the Quantum SYSEX API to send strings (somewhere?)
+
 ### Customizing Makefile options on a per-keymap basis
 
 If your keymap directory has a file called `Makefile` (note the filename), any Makefile options you set in that file will take precedence over other Makefile options for your particular keyboard.
@@ -1162,12 +1166,12 @@ For this mod, you need an unused pin wiring to DI of WS2812 strip. After wiring
 
     RGBLIGHT_ENABLE = yes
 
-In order to use the underglow timer functions, you need to have `#define RGBLIGHT_TIMER` in your `config.h`, and have audio disabled (`AUDIO_ENABLE = no` in your Makefile).
+In order to use the underglow animation functions, you need to have `#define RGBLIGHT_ANIMATIONS` in your `config.h`.
 
 Please add the following options into your config.h, and set them up according your hardware configuration. These settings are for the `F4` pin by default:
 
     #define RGB_DI_PIN F4     // The pin your RGB strip is wired to
-    #define RGBLIGHT_TIMER    // Require for fancier stuff (not compatible with audio)
+    #define RGBLIGHT_ANIMATIONS    // Require for fancier stuff (not compatible with audio)
     #define RGBLED_NUM 14     // Number of LEDs
     #define RGBLIGHT_HUE_STEP 10
     #define RGBLIGHT_SAT_STEP 17
@@ -1318,14 +1322,30 @@ You probably don't want to "brick" your keyboard, making it impossible
 to rewrite firmware onto it.  Here are some of the parameters to show
 what things are (and likely aren't) too risky.
 
-- If a keyboard map does not include RESET, then, to get into DFU
+- If your keyboard map does not include RESET, then, to get into DFU
   mode, you will need to press the reset button on the PCB, which
-  requires unscrewing some bits.
+  requires unscrewing the bottom.
 - Messing with tmk_core / common files might make the keyboard
   inoperable
 - Too large a .hex file is trouble; `make dfu` will erase the block,
   test the size (oops, wrong order!), which errors out, failing to
-  flash the keyboard
+  flash the keyboard, leaving it in DFU mode.
+  - To this end, note that the maximum .hex file size on Planck is
+    7000h (28672 decimal)
+```Linking: .build/planck_rev4_cbbrowne.elf                                                            [OK]
+Creating load file for Flash: .build/planck_rev4_cbbrowne.hex                                       [OK]
+
+Size after:
+   text    data     bss     dec     hex filename
+      0   22396       0   22396    577c planck_rev4_cbbrowne.hex
+```
+  - The above file is of size 22396/577ch, which is less than
+    28672/7000h
+  - As long as you have a suitable alternative .hex file around, you
+    can retry, loading that one
+  - Some of the options you might specify in your keyboard's Makefile
+    consume extra memory; watch out for BOOTMAGIC_ENABLE,
+    MOUSEKEY_ENABLE, EXTRAKEY_ENABLE, CONSOLE_ENABLE, API_SYSEX_ENABLE
 - DFU tools do /not/ allow you to write into the bootloader (unless
   you throw in extra fruitsalad of options), so there is little risk
   there.