Merge remote-tracking branch 'upstream/master'

* upstream/master: (1239 commits)
  Update ez.c
  removes planck/rev3 temporarily
  Move hand_swap_config to ez.c, removes error for infinity
  Update Makefile
  ergodox: Update algernon's keymap to v1.9
  Added VS Code dir to .gitignore
  Support the Pegasus Hoof controller.
  [Jack & Erez] Simplifies and documents TO
  add readme
  use wait_ms instead of _delay_ms
  add messenger
  init keymap
  Add example keymap
  Adding whiskey_tango_foxtrot_capslock ergodox keymap
  Unicode map framework. Allow unicode up to 0xFFFFF using separate mapping table
  CIE 1931 dim curve
  Apply the dim curve to the RGB output
  Update the Cluecard readme files
  Tune snake and knight intervals for Cluecard
  Tunable RGB light intervals
  ...

1 files changed, 80 insertions, 0 deletions

diff --git a/keyboards/lets_split/split_util.c b/keyboards/lets_split/split_util.c
new file mode 100644
index 0000000000..461921798f
--- /dev/null
+++ b/keyboards/lets_split/split_util.c
@@ -0,0 +1,80 @@
+#include <avr/io.h>
+#include <avr/wdt.h>
+#include <avr/power.h>
+#include <avr/interrupt.h>
+#include <util/delay.h>
+#include <avr/eeprom.h>
+#include "split_util.h"
+#include "matrix.h"
+#include "keyboard.h"
+#include "config.h"
+
+#ifdef USE_I2C
+#  include "i2c.h"
+#else
+#  include "serial.h"
+#endif
+
+volatile bool isLeftHand = true;
+
+static void setup_handedness(void) {
+  #ifdef EE_HANDS
+    isLeftHand = eeprom_read_byte(EECONFIG_HANDEDNESS);
+  #else
+    #ifdef I2C_MASTER_RIGHT
+      isLeftHand = !has_usb();
+    #else
+      isLeftHand = has_usb();
+    #endif
+  #endif
+}
+
+static void keyboard_master_setup(void) {
+#ifdef USE_I2C
+    i2c_master_init();
+#else
+    serial_master_init();
+#endif
+}
+
+static void keyboard_slave_setup(void) {
+#ifdef USE_I2C
+    i2c_slave_init(SLAVE_I2C_ADDRESS);
+#else
+    serial_slave_init();
+#endif
+}
+
+bool has_usb(void) {
+   USBCON |= (1 << OTGPADE); //enables VBUS pad
+   _delay_us(5);
+   return (USBSTA & (1<<VBUS));  //checks state of VBUS
+}
+
+void split_keyboard_setup(void) {
+   setup_handedness();
+
+   if (has_usb()) {
+      keyboard_master_setup();
+   } else {
+      keyboard_slave_setup();
+   }
+   sei();
+}
+
+void keyboard_slave_loop(void) {
+   matrix_init();
+
+   while (1) {
+      matrix_slave_scan();
+   }
+}
+
+// this code runs before the usb and keyboard is initialized
+void matrix_setup(void) {
+    split_keyboard_setup();
+
+    if (!has_usb()) {
+        keyboard_slave_loop();
+    }
+}