ARM split - Add support for dfu-util EE_HANDS flashing (#6543)

* Initial stab at some fake dfu-util-split-left behaviour

* Apply suggestions from code review

Co-Authored-By: fauxpark <fauxpark@gmail.com>

* Clang format fixes

* Fake eeprom init for both left and right hand

1 files changed, 13 insertions, 3 deletions

diff --git a/docs/newbs_flashing.md b/docs/newbs_flashing.md
index 3bf582d7f6..4fb2f91d57 100644
--- a/docs/newbs_flashing.md
+++ b/docs/newbs_flashing.md
@@ -215,7 +215,7 @@ Additionally, if you want to flash multiple boards, use the following command:
 When you're done flashing boards, you'll need to hit Ctrl + C or whatever the correct keystroke is for your operating system to break the loop.
 
 
-## HalfKay
+### HalfKay
 
 For the PJRC devices (Teensy's), when you're ready to compile and flash your firmware, open up your terminal window and run the build command: 
 
@@ -248,7 +248,7 @@ Programming.....................................................................
 Booting
 ```
 
-## BootloadHID
+### BootloadHID
 
 For Bootmapper Client(BMC)/bootloadHID/ATmega32A based boards, when you're ready to compile and flash your firmware, open up your terminal window and run the build command: 
 
@@ -284,7 +284,7 @@ Uploading 22016 (0x5600) bytes starting at 0 (0x0)
 0x05580 ... 0x05600
 ```
 
-## STM32 (ARM)
+### STM32 (ARM)
 
 For a majority of ARM boards (including the Proton C, Planck Rev 6, and Preonic Rev 3), when you're ready to compile and flash your firmware, open up your terminal window and run the build command: 
 
@@ -334,6 +334,16 @@ File downloaded successfully
 Transitioning to dfuMANIFEST state
 ```
 
+#### STM32 Commands
+
+There are a number of DFU commands that you can use to flash firmware to a STM32 device:
+
+* `:dfu-util` - The default command for flashing to STM32 devices. 
+* `:dfu-util-wait` - This works like the default command, but it gives you a (configurable) 10 second timeout before it attempts to flash the firmware.  You can use `TIME_DELAY=20` from the command line to change the timeout.
+   * Eg: `make <keyboard>:<keymap>:dfu-util TIME_DELAY=5`
+* `:dfu-util-split-left` - This flashes the normal firmware, just like the default option (`:dfu-util`). However, this also configures the "Left Side" EEPROM setting for split keyboards.
+* `:dfu-util-split-right` - This flashes the normal firmware, just like the default option (`:dfu-util`). However, this also configures the "Right Side" EEPROM setting for split keyboards.
+
 ## Test It Out!
 
 Congrats! Your custom firmware has been programmed to your keyboard!