diff --git a/GP2040-CE/headers/gba/GBAKey.h b/GP2040-CE/headers/gba/GBAKey.h
new file mode 100644
index 0000000..14d9382
--- /dev/null
+++ b/GP2040-CE/headers/gba/GBAKey.h
@@ -0,0 +1,14 @@
+#pragma once
+
+enum GBAKey : uint32_t {
+	A = 1 << 0,
+	B = 1 << 1,
+	SELECT = 1 << 2,
+	START = 1 << 3,
+	RIGHT = 1 << 4,
+	LEFT = 1 << 5,
+	UP = 1 << 6,
+	DOWN = 1 << 7,
+	R = 1 << 8,
+	L = 1 << 9
+};
diff --git a/GP2040-CE/headers/gba/multiboot.h b/GP2040-CE/headers/gba/multiboot.h
index 11f957c..df74efc 100644
--- a/GP2040-CE/headers/gba/multiboot.h
+++ b/GP2040-CE/headers/gba/multiboot.h
@@ -5,8 +5,7 @@
  * https://github.com/akkera102/gba_03_multiboot
  */
 
-#ifndef _GBA_SPI32_H_
-#define _GBA_SPI32_H_
+#pragma once
 
 #include <cstdint>
 
@@ -14,9 +13,7 @@ namespace gba
 {
 
 /// @return `true`  if ROM is sent
-/// @return `false` if GBA program is already running, and only `L` is pressed on it
+/// @return `false` if GBA program is already running, and only `Start` is pressed on it
 bool sendGBARom(const uint8_t* romAddr, uint32_t romSize);
 
 }
-
-#endif
\ No newline at end of file
diff --git a/GP2040-CE/headers/gba/spi32.h b/GP2040-CE/headers/gba/spi32.h
index 8210e71..6a7c146 100644
--- a/GP2040-CE/headers/gba/spi32.h
+++ b/GP2040-CE/headers/gba/spi32.h
@@ -2,8 +2,7 @@
  * SPDX-License-Identifier: CC0-1.0
  */
 
-#ifndef _GBA_SPI32_H_
-#define _GBA_SPI32_H_
+#pragma once
 
 // Pico SPI
 #include "hardware/spi.h"
@@ -18,5 +17,3 @@ void deinitSpi32();
 uint32_t spi32(uint32_t val);
 
 }
-
-#endif
diff --git a/GP2040-CE/src/gamepad.cpp b/GP2040-CE/src/gamepad.cpp
index 84ef020..634f49b 100644
--- a/GP2040-CE/src/gamepad.cpp
+++ b/GP2040-CE/src/gamepad.cpp
@@ -14,6 +14,7 @@
 #include "CRC32.h"
 
 #include "gba/spi32.h"
+#include "gba/GBAKey.h"
 
 // MUST BE DEFINED for mpgs
 uint32_t getMillis() {
@@ -180,19 +181,6 @@ void Gamepad::read()
 {
 	constexpr uint32_t GBA_SPI_ERROR = 0xFFFFFFFFu;
 
-	enum GBAKey : uint32_t {
-		A = 1 << 0,
-		B = 1 << 1,
-		SELECT = 1 << 2,
-		START = 1 << 3,
-		RIGHT = 1 << 4,
-		LEFT = 1 << 5,
-		UP = 1 << 6,
-		DOWN = 1 << 7,
-		R = 1 << 8,
-		L = 1 << 9
-	};
-
 	uint32_t received = gba::spi32(state.buttons);
 
 	if (received == GBA_SPI_ERROR) {
diff --git a/GP2040-CE/src/gba/multiboot.cpp b/GP2040-CE/src/gba/multiboot.cpp
index 4c40ce1..921c18b 100644
--- a/GP2040-CE/src/gba/multiboot.cpp
+++ b/GP2040-CE/src/gba/multiboot.cpp
@@ -5,11 +5,14 @@
  * https://github.com/akkera102/gba_03_multiboot
  */
 
-#include "gba/spi32.h"
+#include "gba/multiboot.h"
 
 #include <cstdlib>
 #include "pico/stdlib.h"
 
+#include "gba/spi32.h"
+#include "gba/GBAKey.h"
+
 namespace gba
 {
 
@@ -34,10 +37,10 @@ bool sendGBARom(const uint8_t* romAddr, const uint32_t romSize) {
     do {
         recv = gba::spi32(0x6202);
         sleep_ms(10);
-    } while ((recv >> 16) != 0x7202 && recv != (1 << 9));
+    } while ((recv >> 16) != 0x7202 && recv != (GBAKey::START));
 
-    // if GBA program is already running, and only `L` is pressed on it
-    if (recv == (1 << 9))
+    // if GBA program is already running, and only `Start` is pressed on it
+    if (recv == (GBAKey::START))
         return false;
     
     // -----------------------------------------------------
diff --git a/GP2040-CE/src/gp2040.cpp b/GP2040-CE/src/gp2040.cpp
index 25cc08b..ca7b832 100644
--- a/GP2040-CE/src/gp2040.cpp
+++ b/GP2040-CE/src/gp2040.cpp
@@ -177,11 +177,13 @@ GP2040::BootAction GP2040::getBootAction() {
 
 				if (gamepad->pressedF1() && gamepad->pressedUp()) {
 					return BootAction::ENTER_USB_MODE;
-				} else if (gamepad->pressedS2()) {
-					return BootAction::ENTER_WEBCONFIG_MODE;
-				} else if (gamepad->pressedB3()) { // P1
+				}
+				// else if (gamepad->pressedS2()) {
+				// 	return BootAction::ENTER_WEBCONFIG_MODE;
+				// }
+				  else if (gamepad->pressedL1()) { // P1
 					return BootAction::SET_INPUT_MODE_HID;
-				} else if (gamepad->pressedB4()) { // P2
+				} else if (gamepad->pressedR1()) { // P2
 					return BootAction::SET_INPUT_MODE_PS4;
 				} else if (gamepad->pressedB1()) { // K1
 					return BootAction::SET_INPUT_MODE_SWITCH;
diff --git a/README.md b/README.md
index d8f2223..e7e197f 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ Proof-of-concept Game Boy Advance (GBA) to USB controller, which uses Raspberry
 [![](https://img.youtube.com/vi/JmBufgcb4Gw/hqdefault.jpg)](https://www.youtube.com/watch?v=JmBufgcb4Gw "Youtube video for gba-pico-gamepad")
 
 
-# How it works
+# How it's done
 
 This project is essentially a modified version of [GP2040-CE](https://github.com/OpenStickCommunity/GP2040-CE) that enables communication with the Game Boy Advance using the GBA link cable.
 
@@ -43,16 +43,17 @@ And that's about it.
 
 4. Plug the USB Cable to your PC.\
    It will start sending the program once the GBA is ready.
-    * You can [hold down certain key on boot to change Input Mode.](https://gp2040-ce.info/#/usage?id=input-modes)
+    * You can hold down certain key on boot to change Input Mode.
+        + Note that the key binding is differ from the [original](https://gp2040-ce.info/#/usage?id=input-modes).
         + Hold `B` on boot -> Nintendo Switch
         + Hold `A` on boot -> XInput
-        + The other options cannot be pressed with keys on the GBA,\
-          but no modifications are done yet to deal with that.
+        + Hold `L` on boot -> DirectInput/PS3
+        + Hold `R` on boot -> PS4
     * You can [change the D-Pad Mode anytime with certain key combination.](https://gp2040-ce.info/#/usage?id=d-pad-modes)
     * GP2040-CE's Web Config is disabled.
 
 5. Enjoy your GBA as an USB gamepad.
-    * If you accidentally pulled out your cable, you can re-plug it and press `L` to reconnect.
+    * If you accidentally pulled out your cable, you can re-plug it and press `Start` to reconnect.
 
 
 # Build