diff --git a/arm11/source/main.c b/arm11/source/main.c
index 7c186cc8f..48fecbc56 100644
--- a/arm11/source/main.c
+++ b/arm11/source/main.c
@@ -123,8 +123,8 @@ static void initScreens(u32 brightnessLevel, struct fb *fbs)
     for(u32 i = 0; i < 256; i++)
         *(vu32 *)0x10400584 = 0x10101 * i;
 
-    //*(vu32 *)0x10202204 = 0x00000000; //unset LCD fill
-    //*(vu32 *)0x10202A04 = 0x00000000;
+    *(vu32 *)0x10202204 = 0x00000000; //unset LCD fill
+    *(vu32 *)0x10202A04 = 0x00000000;
 }
 
 static void setupFramebuffers(struct fb *fbs)
diff --git a/arm9/linker.ld b/arm9/linker.ld
index 4cde67bb3..4365b8c38 100644
--- a/arm9/linker.ld
+++ b/arm9/linker.ld
@@ -45,19 +45,16 @@ SECTIONS
 
         chainloader.o(.text*)
         i2c.o(.text*)
-        mcu.o(.text*)
         arm9_exception_handlers.o(.text*)
 
         *(.arm9_exception_handlers.rodata*)
         chainloader.o(.rodata*)
         i2c.o(.rodata*)
-        mcu.o(.rodata*)
         arm9_exception_handlers.o(.rodata*)
 
         *(.arm9_exception_handlers.data*)
         chainloader.o(.data*)
         i2c.o(.data*)
-        mcu.o(.data*)
         arm9_exception_handlers.o(.data*)
         . = ALIGN(32);
     } >itcm AT>main :itcm
@@ -70,7 +67,6 @@ SECTIONS
         *(.arm9_exception_handlers.bss*)
         chainloader.o(.bss* COMMON)
         i2c.o(.bss* COMMON)
-        mcu.o(.bss* COMMON)
         arm9_exception_handlers.o(.bss* COMMON)
         . = ALIGN(32);
         PROVIDE (__itcm_end__ = ABSOLUTE(.));
diff --git a/arm9/source/arm9_exception_handlers.c b/arm9/source/arm9_exception_handlers.c
index 2cca61a3a..d7fbed38a 100644
--- a/arm9/source/arm9_exception_handlers.c
+++ b/arm9/source/arm9_exception_handlers.c
@@ -25,7 +25,8 @@
 */
 
 #include "arm9_exception_handlers.h"
-#include "mcu.h"
+#include "i2c.h"
+#include "screen.h"
 
 #define FINAL_BUFFER    0x25000000
 
@@ -102,9 +103,10 @@ void __attribute__((noreturn)) arm9ExceptionHandlerMain(u32 *registerDump, u32 t
     //Copy header (actually optimized by the compiler)
     *(ExceptionDumpHeader *)FINAL_BUFFER = dumpHeader;
 
-    mcuPowerBacklightsOff();
+    if(ARESCREENSINITIALIZED) I2C_writeReg(I2C_DEV_MCU, 0x22, 1 << 0); //Shutdown LCD
 
     ((void (*)())0xFFFF0830)(); //Ensure that all memory transfers have completed and that the data cache has been flushed
 
-    mcuReboot();
+    I2C_writeReg(I2C_DEV_MCU, 0x20, 1 << 2); //Reboot
+    while(true);
 }
diff --git a/arm9/source/exceptions.c b/arm9/source/exceptions.c
index ae8f9f967..07106840e 100644
--- a/arm9/source/exceptions.c
+++ b/arm9/source/exceptions.c
@@ -200,5 +200,5 @@ void detectAndProcessExceptionDumps(void)
 
 exit:
     memset((void *)dumpHeader, 0, dumpHeader->totalSize);
-    powerOff();
+    mcuPowerOff();
 }
diff --git a/arm9/source/firm.c b/arm9/source/firm.c
index 210aaa5cc..ce44d7e43 100755
--- a/arm9/source/firm.c
+++ b/arm9/source/firm.c
@@ -37,7 +37,6 @@
 #include "screen.h"
 #include "fmt.h"
 #include "chainloader.h"
-#include "mcu.h"
 
 static Firm *firm = (Firm *)0x20001000;
 
@@ -565,7 +564,6 @@ u32 patch1x2xNativeAndSafeFirm(void)
 
 void launchFirm(int argc, char **argv)
 {
-    mcuFinalize();
     prepareArm11ForFirmlaunch();
     chainload(argc, argv, firm);
 }
diff --git a/arm9/source/gpio.h b/arm9/source/gpio.h
deleted file mode 100644
index 4e5dd5fd9..000000000
--- a/arm9/source/gpio.h
+++ /dev/null
@@ -1,225 +0,0 @@
-/*
-*   This file is part of Luma3DS
-*   Copyright (C) 2021 Aurora Wright, TuxSH
-*
-*   This program is free software: you can redistribute it and/or modify
-*   it under the terms of the GNU General Public License as published by
-*   the Free Software Foundation, either version 3 of the License, or
-*   (at your option) any later version.
-*
-*   This program is distributed in the hope that it will be useful,
-*   but WITHOUT ANY WARRANTY; without even the implied warranty of
-*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-*   GNU General Public License for more details.
-*
-*   You should have received a copy of the GNU General Public License
-*   along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*
-*   Additional Terms 7.b and 7.c of GPLv3 apply to this file:
-*       * Requiring preservation of specified reasonable legal notices or
-*         author attributions in that material or in the Appropriate Legal
-*         Notices displayed by works containing it.
-*       * Prohibiting misrepresentation of the origin of that material,
-*         or requiring that modified versions of such material be marked in
-*         reasonable ways as different from the original version.
-*/
-
-#pragma once
-
-#include "types.h"
-
-typedef struct GpioRegisters {
-    u8 gpio1_data;
-    u8 _0x001[0x010 - 0x001];
-
-    u8 gpio2_data;
-    u8 gpio2_dir;
-    u8 gpio2_intcfg;
-    u8 gpio2_inten;
-    u16 gpio2_data2;
-    u8 _0x016[0x020 - 0x016];
-
-    u16 gpio3_data;
-    u16 gpio3_dir;
-    u16 gpio3_intcfg;
-    u16 gpio3_inten;
-    u16 gpio3_data2;
-    u8 _0x02a[0x100 - 0x02A];
-} GpioRegisters;
-
-typedef enum GpioDirection {
-    GPIO_DIR_INPUT  = 0,
-    GPIO_DIR_OUTPUT = 1,
-} GpioDirection;
-
-typedef enum GpioInterruptConfig {
-    GPIO_INTCFG_FALLING_EDGE    = 0,
-    GPIO_INTCFG_RISING_EDGE     = 1,
-} GpioInterruptConfig;
-
-#define GPIO_PIN(bank, idx) (((bank) << 4) | ((idx) & 0xF))
-#define BANK_OF(pin)        ((pin) >> 4)
-#define BIT_OF(pin)         ((pin) & 0xF)
-
-typedef enum GpioPin {
-    // GPIO1
-    GPIO_DEBUG_BUTTON           = GPIO_PIN(1, 0), // active-low
-    GPIO_TOUCH_SCREEN           = GPIO_PIN(1, 1), // active-low, 0 when the touch screen is pressed
-    GPIO_SHELL_CLOSED           = GPIO_PIN(1, 2),
-
-    // GPIO2
-    GPIO_HEADPHONES_INSERTED    = GPIO_PIN(2, 0),
-    GPIO_TWL_DEPOP              = GPIO_PIN(2, 1), // active-low
-
-    // GPIO2 (DATA2)
-    GPIO_WIFI_MODE              = GPIO_PIN(4, 0), // 0 is CTR, 1 is MP (DS WiFi)
-
-    // GPIO3
-    GPIO_CSTICK_INT             = GPIO_PIN(3, 0),
-    GPIO_IRDA_INT               = GPIO_PIN(3, 1), // active-low
-    GPIO_GYRO_INT               = GPIO_PIN(3, 2),
-    GPIO_CSTICK_STOP            = GPIO_PIN(3, 3), // output
-    GPIO_IRDA_TXRC              = GPIO_PIN(3, 4), // output
-    GPIO_IRDA_RXD               = GPIO_PIN(3, 5), // active-low
-    GPIO_NFC_OUT1               = GPIO_PIN(3, 6), // output
-    GPIO_NFC_OUT2               = GPIO_PIN(3, 7), // output
-    GPIO_HEADPHONES_BUTTON      = GPIO_PIN(3, 8), // active-low ("half-inserted")
-    GPIO_MCU_INT                = GPIO_PIN(3, 9),
-    GPIO_NFC_INT                = GPIO_PIN(3, 10),
-    GPIO_QTM_OUT                = GPIO_PIN(3, 11), // output
-
-    // GPIO3 (DATA2)
-    GPIO_WIFI_ENABLED           = GPIO_PIN(5, 0),
-} GpioPin;
-
-static volatile GpioRegisters *const GPIO = (volatile GpioRegisters *)0x10147000;
-
-static inline bool gpioRead(GpioPin pin)
-{
-    u32 bank = BANK_OF(pin);
-    u32 bit = BIT_OF(pin);
-
-    switch (bank) {
-        case 1:
-            return (GPIO->gpio1_data & BIT(bit)) != 0;
-        case 2:
-            return (GPIO->gpio2_data & BIT(bit)) != 0;
-        case 3:
-            return (GPIO->gpio3_data & BIT(bit)) != 0;
-        case 4:
-            return (GPIO->gpio2_data2 & BIT(bit)) != 0;
-        case 5:
-            return (GPIO->gpio3_data2 & BIT(bit)) != 0;
-
-        default:
-            return false;
-    }
-}
-
-static inline void gpioWrite(GpioPin pin, bool val)
-{
-    u32 bank = BANK_OF(pin);
-    u32 bit = BIT_OF(pin);
-
-    u32 valMask = (val ? 1 : 0) << bit;
-    u32 tmp;
-
-    switch (bank) {
-        case 1:
-            tmp = GPIO->gpio1_data & ~BIT(bit);
-            GPIO->gpio1_data = (u8)(tmp | valMask);
-            break;
-        case 2:
-            tmp = GPIO->gpio2_data & ~BIT(bit);
-            GPIO->gpio2_data = (u8)(tmp | valMask);
-            break;
-        case 3:
-            tmp = GPIO->gpio3_data & ~BIT(bit);
-            GPIO->gpio3_data = (u16)(tmp | valMask);
-            break;
-        case 4:
-            tmp = GPIO->gpio2_data2 & ~BIT(bit);
-            GPIO->gpio2_data2 = (u16)(tmp | valMask);
-            break;
-        case 5:
-            tmp = GPIO->gpio3_data2 & ~BIT(bit);
-            GPIO->gpio3_data2 = (u16)(tmp | valMask);
-            break;
-
-        default:
-            break;
-    }
-}
-
-static inline void gpioSetDirection(GpioPin pin, GpioDirection direction)
-{
-    u32 bank = BANK_OF(pin);
-    u32 bit = BIT_OF(pin);
-
-    u32 valMask = (direction == GPIO_DIR_OUTPUT ? 1 : 0) << bit;
-    u32 tmp;
-
-    switch (bank) {
-        case 2:
-            tmp = GPIO->gpio2_dir & ~BIT(bit);
-            GPIO->gpio2_dir = (u8)(tmp | valMask);
-            break;
-        case 3:
-            tmp = GPIO->gpio3_dir & ~BIT(bit);
-            GPIO->gpio3_dir = (u16)(tmp | valMask);
-            break;
-
-        default:
-            break;
-    }
-}
-
-static inline void gpioConfigureInterrupt(GpioPin pin, GpioInterruptConfig cfg)
-{
-    u32 bank = BANK_OF(pin);
-    u32 bit = BIT_OF(pin);
-
-    u32 valMask = (cfg == GPIO_INTCFG_RISING_EDGE ? 1 : 0) << bit;
-    u32 tmp;
-
-    switch (bank) {
-        case 2:
-            tmp = GPIO->gpio2_intcfg & ~BIT(bit);
-            GPIO->gpio2_intcfg = (u8)(tmp | valMask);
-            break;
-        case 3:
-            tmp = GPIO->gpio3_data & ~BIT(bit);
-            GPIO->gpio3_intcfg = (u16)(tmp | valMask);
-            break;
-
-        default:
-            break;
-    }
-}
-
-static inline void gpioSetInterruptEnabled(GpioPin pin, bool enabled)
-{
-    u32 bank = BANK_OF(pin);
-    u32 bit = BIT_OF(pin);
-
-    u32 valMask = (enabled ? 1 : 0) << bit;
-    u32 tmp;
-
-    switch (bank) {
-        case 2:
-            tmp = GPIO->gpio2_inten & ~BIT(bit);
-            GPIO->gpio2_inten = (u8)(tmp | valMask);
-            break;
-        case 3:
-            tmp = GPIO->gpio3_inten & ~BIT(bit);
-            GPIO->gpio3_inten = (u16)(tmp | valMask);
-            break;
-
-        default:
-            break;
-    }
-}
-
-#undef GPIO_PIN
-#undef BIT_OF
-#undef BANK_OF
diff --git a/arm9/source/i2c.c b/arm9/source/i2c.c
index 20b60b302..d2d37e8bb 100644
--- a/arm9/source/i2c.c
+++ b/arm9/source/i2c.c
@@ -16,10 +16,7 @@
  *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-// Modified 2021 TuxSH
-
 #include <stdbool.h>
-#include <string.h>
 #include "types.h"
 #include "i2c.h"
 #include "utils.h"
@@ -161,11 +158,11 @@ static bool i2cStartTransfer(I2cDevice devId, u8 regAddr, bool read, I2cRegs *co
     else return false;
 }
 
-bool I2C_readRegBuf(I2cDevice devId, u8 regAddr, void *out, u32 size)
+bool I2C_readRegBuf(I2cDevice devId, u8 regAddr, u8 *out, u32 size)
 {
     const u8 busId = i2cDevTable[devId].busId;
     I2cRegs *const regs = i2cGetBusRegsBase(busId);
-    u8 *out8 = (u8 *)out;
+
 
     if(!i2cStartTransfer(devId, regAddr, true, regs)) return false;
 
@@ -173,28 +170,27 @@ bool I2C_readRegBuf(I2cDevice devId, u8 regAddr, void *out, u32 size)
     {
         regs->REG_I2C_CNT = I2C_ENABLE | I2C_IRQ_ENABLE | I2C_DIRE_READ | I2C_ACK;
         i2cWaitBusy(regs);
-        *out8++ = regs->REG_I2C_DATA;
+        *out++ = regs->REG_I2C_DATA;
     }
 
     regs->REG_I2C_CNT = I2C_ENABLE | I2C_IRQ_ENABLE | I2C_DIRE_READ | I2C_STOP;
     i2cWaitBusy(regs);
-    *out8 = regs->REG_I2C_DATA; // Last byte
+    *out = regs->REG_I2C_DATA; // Last byte
 
     return true;
 }
 
-bool I2C_writeRegBuf(I2cDevice devId, u8 regAddr, const void *in, u32 size)
+bool I2C_writeRegBuf(I2cDevice devId, u8 regAddr, const u8 *in, u32 size)
 {
     const u8 busId = i2cDevTable[devId].busId;
     I2cRegs *const regs = i2cGetBusRegsBase(busId);
-    const u8 *in8 = (const u8 *)in;
 
 
     if(!i2cStartTransfer(devId, regAddr, false, regs)) return false;
 
     while(--size)
     {
-        regs->REG_I2C_DATA = *in8++;
+        regs->REG_I2C_DATA = *in++;
         regs->REG_I2C_CNT = I2C_ENABLE | I2C_IRQ_ENABLE | I2C_DIRE_WRITE;
         i2cWaitBusy(regs);
         if(!I2C_GET_ACK(regs->REG_I2C_CNT)) // If ack flag is 0 it failed.
@@ -204,7 +200,7 @@ bool I2C_writeRegBuf(I2cDevice devId, u8 regAddr, const void *in, u32 size)
         }
     }
 
-    regs->REG_I2C_DATA = *in8;
+    regs->REG_I2C_DATA = *in;
     regs->REG_I2C_CNT = I2C_ENABLE | I2C_IRQ_ENABLE | I2C_DIRE_WRITE | I2C_STOP;
     i2cWaitBusy(regs);
     if(!I2C_GET_ACK(regs->REG_I2C_CNT)) // If ack flag is 0 it failed.
diff --git a/arm9/source/i2c.h b/arm9/source/i2c.h
index ce2e9cb83..ea9442250 100644
--- a/arm9/source/i2c.h
+++ b/arm9/source/i2c.h
@@ -66,7 +66,7 @@ void I2C_init(void);
  *
  * @return     Returns true on success and false on failure.
  */
-bool I2C_readRegBuf(I2cDevice devId, u8 regAddr, void *out, u32 size);
+bool I2C_readRegBuf(I2cDevice devId, u8 regAddr, u8 *out, u32 size);
 
 /**
  * @brief      Writes a buffer to a I2C register.
@@ -78,7 +78,7 @@ bool I2C_readRegBuf(I2cDevice devId, u8 regAddr, void *out, u32 size);
  *
  * @return     Returns true on success and false on failure.
  */
-bool I2C_writeRegBuf(I2cDevice devId, u8 regAddr, const void *in, u32 size);
+bool I2C_writeRegBuf(I2cDevice devId, u8 regAddr, const u8 *in, u32 size);
 
 /**
  * @brief      Reads a byte from a I2C register.
diff --git a/arm9/source/main.c b/arm9/source/main.c
index 7360cecb7..50b66668c 100644
--- a/arm9/source/main.c
+++ b/arm9/source/main.c
@@ -36,7 +36,7 @@
 #include "crypto.h"
 #include "memory.h"
 #include "screen.h"
-#include "mcu.h"
+#include "i2c.h"
 #include "fatfs/sdmmc/sdmmc.h"
 
 extern u8 __itcm_start__[], __itcm_lma__[], __itcm_bss_start__[], __itcm_end__[];
@@ -116,8 +116,7 @@ void main(int argc, char **argv, u32 magicWord)
     // Set up the additional sections, overwrites argc
     memcpy(__itcm_start__, __itcm_lma__, __itcm_bss_start__ - __itcm_start__);
     memset(__itcm_bss_start__, 0, __itcm_end__ - __itcm_bss_start__);
-    mcuInit();
-
+    I2C_init();
     if(isInvalidLoader) error("Launched using an unsupported loader.");
 
     installArm9Handlers();
@@ -142,7 +141,7 @@ void main(int argc, char **argv, u32 magicWord)
         {
             while(HID_PAD & NTRBOOT_BUTTONS);
             loadHomebrewFirm(0);
-            powerOff();
+            mcuPowerOff();
         }
     }
     else
@@ -165,7 +164,7 @@ void main(int argc, char **argv, u32 magicWord)
     //Determine if this is a firmlaunch boot
     if(bootType == FIRMLAUNCH)
     {
-        if(needConfig == CREATE_CONFIGURATION) powerOff();
+        if(needConfig == CREATE_CONFIGURATION) mcuPowerOff();
 
         switch(firmlaunchTidLow & 0xF)
         {
diff --git a/arm9/source/mcu.c b/arm9/source/mcu.c
deleted file mode 100644
index f88a4a71d..000000000
--- a/arm9/source/mcu.c
+++ /dev/null
@@ -1,127 +0,0 @@
-/*
-*   This file is part of Luma3DS
-*   Copyright (C) 2021 Aurora Wright, TuxSH
-*
-*   This program is free software: you can redistribute it and/or modify
-*   it under the terms of the GNU General Public License as published by
-*   the Free Software Foundation, either version 3 of the License, or
-*   (at your option) any later version.
-*
-*   This program is distributed in the hope that it will be useful,
-*   but WITHOUT ANY WARRANTY; without even the implied warranty of
-*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-*   GNU General Public License for more details.
-*
-*   You should have received a copy of the GNU General Public License
-*   along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*
-*   Additional Terms 7.b and 7.c of GPLv3 apply to this file:
-*       * Requiring preservation of specified reasonable legal notices or
-*         author attributions in that material or in the Appropriate Legal
-*         Notices displayed by works containing it.
-*       * Prohibiting misrepresentation of the origin of that material,
-*         or requiring that modified versions of such material be marked in
-*         reasonable ways as different from the original version.
-*/
-
-#include "mcu.h"
-#include "i2c.h"
-#include "gpio.h"
-
-static u32 g_pendingMcuInterrupts = 0;
-
-u32 mcuGetInterruptMask(void)
-{
-    u32 mask;
-    I2C_readRegBuf(I2C_DEV_MCU, 0x18, &mask, 4);
-    return mask;
-}
-
-void mcuSetInterruptMask(u32 mask)
-{
-    I2C_writeRegBuf(I2C_DEV_MCU, 0x18, &mask, 4);
-}
-
-u32 mcuGetPendingInterrupts(u32 mask)
-{
-    u32 curMcuInts = 0;
-    if (gpioRead(GPIO_MCU_INT))
-    {
-        // MCU IRQ pin raised
-        I2C_readRegBuf(I2C_DEV_MCU, 0x10, &curMcuInts, 4); // this clears the interrupts on the MCU side
-
-        // Add all new MCU interrupts to the pending list
-        g_pendingMcuInterrupts |= curMcuInts;
-    }
-
-    // Remove the interrupts we'll return from the pending list
-    u32 ret = g_pendingMcuInterrupts & mask;
-    g_pendingMcuInterrupts &= ~mask;
-    return ret;
-}
-
-void mcuPowerBacklightsOn(void)
-{
-    // Doesn't matter if they're already on, it should be idempotent on the MCU side
-
-    u32 prevMask = mcuGetInterruptMask();
-    u32 pend = 0;
-
-    mcuSetInterruptMask(~MCU_INT_LCD_BL_ON);
-    mcuGetPendingInterrupts(MCU_INT_LCD_BL_ON) ; // Clear any pending interrupts
-    I2C_writeReg(I2C_DEV_MCU, 0x22, (u8)(MCU_INT_LCD_BL_ON >> 24));
-
-    // Wait for LCD and backlights to be on
-    do
-    {
-        pend |= mcuGetPendingInterrupts(MCU_INT_LCD_BL_ON);
-    } while (pend != MCU_INT_LCD_BL_ON);
-
-    mcuSetInterruptMask(prevMask);
-}
-
-void mcuPowerBacklightsOff(void)
-{
-    // Doesn't matter if they're already off, it should be idempotent on the MCU side
-
-    u32 prevMask = mcuGetInterruptMask();
-    u32 pend = 0;
-
-    mcuSetInterruptMask(~MCU_INT_LCD_BL_OFF);
-    mcuGetPendingInterrupts(MCU_INT_LCD_BL_OFF) ; // Clear any pending interrupts
-    I2C_writeReg(I2C_DEV_MCU, 0x22, (u8)(MCU_INT_LCD_BL_OFF >> 24));
-
-    // Wait for LCD and backlights to be off
-    do
-    {
-        pend |= mcuGetPendingInterrupts(MCU_INT_LCD_BL_OFF);
-    } while (pend != MCU_INT_LCD_BL_OFF);
-
-    mcuSetInterruptMask(prevMask);
-}
-
-void mcuPowerOff(void)
-{
-    mcuFinalize();
-    I2C_writeReg(I2C_DEV_MCU, 0x20, BIT(0));
-    while(true);
-}
-
-void mcuReboot(void)
-{
-    mcuFinalize();
-    I2C_writeReg(I2C_DEV_MCU, 0x20, BIT(2));
-    while(true);
-}
-
-void mcuInit(void)
-{
-    I2C_init();
-    mcuSetInterruptMask(~MCU_INT_MASK_FOR_INPUT);
-}
-
-void mcuFinalize(void)
-{
-    mcuGetPendingInterrupts(0xFFFFFFFF); // purge pending MCU interrupts & internal pending list
-    mcuSetInterruptMask(~MCU_INT_DEFAULT_MASK); // Reset MCU mask
-}
diff --git a/arm9/source/mcu.h b/arm9/source/mcu.h
deleted file mode 100644
index e26a3a175..000000000
--- a/arm9/source/mcu.h
+++ /dev/null
@@ -1,55 +0,0 @@
-/*
-*   This file is part of Luma3DS
-*   Copyright (C) 2021 Aurora Wright, TuxSH
-*
-*   This program is free software: you can redistribute it and/or modify
-*   it under the terms of the GNU General Public License as published by
-*   the Free Software Foundation, either version 3 of the License, or
-*   (at your option) any later version.
-*
-*   This program is distributed in the hope that it will be useful,
-*   but WITHOUT ANY WARRANTY; without even the implied warranty of
-*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-*   GNU General Public License for more details.
-*
-*   You should have received a copy of the GNU General Public License
-*   along with this program.  If not, see <http://www.gnu.org/licenses/>.
-*
-*   Additional Terms 7.b and 7.c of GPLv3 apply to this file:
-*       * Requiring preservation of specified reasonable legal notices or
-*         author attributions in that material or in the Appropriate Legal
-*         Notices displayed by works containing it.
-*       * Prohibiting misrepresentation of the origin of that material,
-*         or requiring that modified versions of such material be marked in
-*         reasonable ways as different from the original version.
-*/
-
-#pragma once
-
-#include "types.h"
-
-/*
- * Bit13:   Battery low (at 10%, 5% and sub-1%)
- * Bit7:    MCU WDT reset
- * Bit6:    Shell opened (GPIO1_0 1->0)
- * Bit5:    Shell closed (GPIO1_0 0->1)
- * Bit1:    Power button held
- * Bit0:    Power button pressed
- */
-#define MCU_INT_MASK_FOR_INPUT  (BIT(13)|BIT(7)|BIT(6)|BIT(5)|BIT(1)|BIT(0))
-#define MCU_INT_LCD_BL_ON       (BIT(29)|BIT(27)|BIT(25))
-#define MCU_INT_LCD_BL_OFF      (BIT(28)|BIT(26)|BIT(24))
-#define MCU_INT_DEFAULT_MASK    0x0000E7FFu
-
-u32 mcuGetInterruptMask(void);
-void mcuSetInterruptMask(u32 mask); // 1 for each interrupt you want to *disable* (mask)
-u32 mcuGetPendingInterrupts(u32 mask);
-
-void mcuPowerBacklightsOn(void);
-void mcuPowerBacklightsOff(void);
-
-void NORETURN mcuPowerOff(void);
-void NORETURN mcuReboot(void);
-
-void mcuInit(void);
-void mcuFinalize(void);
diff --git a/arm9/source/pin.c b/arm9/source/pin.c
index 50c79665b..a2cf2e2be 100644
--- a/arm9/source/pin.c
+++ b/arm9/source/pin.c
@@ -198,7 +198,7 @@ bool verifyPin(u32 pinMode)
         }
         while(!(pressed & PIN_BUTTONS));
 
-        if(pressed & BUTTON_START) powerOff();
+        if(pressed & BUTTON_START) mcuPowerOff();
 
         pressed &= PIN_BUTTONS;
 
diff --git a/arm9/source/screen.c b/arm9/source/screen.c
index d6860190d..bb01525be 100644
--- a/arm9/source/screen.c
+++ b/arm9/source/screen.c
@@ -32,7 +32,8 @@
 #include "screen.h"
 #include "config.h"
 #include "memory.h"
-#include "mcu.h"
+#include "i2c.h"
+#include "utils.h"
 
 bool needToSetupScreens = true;
 
@@ -68,7 +69,6 @@ void prepareArm11ForFirmlaunch(void)
 
 void deinitScreens(void)
 {
-    mcuPowerBacklightsOff();
     if(ARESCREENSINITIALIZED) invokeArm11Function(DEINIT_SCREENS);
 }
 
@@ -102,20 +102,19 @@ void initScreens(void)
             memcpy((void *)(ARM11_PARAMETERS_ADDRESS + 4), fbs, sizeof(fbs));
             invokeArm11Function(INIT_SCREENS);
 
-            mcuPowerBacklightsOn();
+            //Turn on backlight
+            I2C_writeReg(I2C_DEV_MCU, 0x22, 0x2A);
+            wait(5);
         }
         else updateBrightness(MULTICONFIG(BRIGHTNESS));
 
-        clearScreens(false);
-        clearScreens(true);
-
         memcpy((void *)ARM11_PARAMETERS_ADDRESS, fbs, sizeof(fbs));
         invokeArm11Function(SETUP_FRAMEBUFFERS);
+
+        clearScreens(true);
         needToSetupScreens = false;
     }
-    else
-    {
-        clearScreens(false);
-        swapFramebuffers(false);
-    }
+
+    clearScreens(false);
+    swapFramebuffers(false);
 }
diff --git a/arm9/source/types.h b/arm9/source/types.h
index 01517b8c2..e4646bbc4 100644
--- a/arm9/source/types.h
+++ b/arm9/source/types.h
@@ -49,14 +49,6 @@ typedef volatile s16 vs16;
 typedef volatile s32 vs32;
 typedef volatile s64 vs64;
 
-/// Creates a bitmask from a bit number.
-#define BIT(n) (1U<<(n))
-
-/// Aligns a struct (and other types?) to m, making sure that the size of the struct is a multiple of m.
-#define ALIGN(m)   __attribute__((aligned(m)))
-
-#define NORETURN __attribute__((noreturn))
-
 #include "3dsheaders.h"
 
 #define CFG_BOOTENV         (*(vu32 *)0x10010000)
diff --git a/arm9/source/utils.c b/arm9/source/utils.c
index 7089071d5..d789761fe 100644
--- a/arm9/source/utils.c
+++ b/arm9/source/utils.c
@@ -37,7 +37,6 @@
 #include "fmt.h"
 #include "memory.h"
 #include "fs.h"
-#include "mcu.h"
 
 static void startChrono(void)
 {
@@ -66,24 +65,13 @@ static u64 chrono(void)
     return res;
 }
 
-void powerOff(void)
-{
-    if(!needToSetupScreens) clearScreens(false);
-
-    mcuPowerBacklightsOff();
-
-    // Ensure that all memory transfers have completed and that the data cache has been flushed
-    flushEntireDCache();
-
-    mcuPowerOff();
-}
-
 u32 waitInput(bool isMenu)
 {
     static u64 dPadDelay = 0ULL;
     u64 initialValue = 0ULL;
     u32 key,
         oldKey = HID_PAD;
+    bool shouldShellShutdown = bootType != B9SNTR && bootType != NTR;
 
     if(isMenu)
     {
@@ -94,34 +82,21 @@ u32 waitInput(bool isMenu)
 
     while(true)
     {
-        // There are two sources of truth for the shell state: the gpio reg and the MCU
-
-        /*
-         * Bit13:   Battery low (at 10%, 5% and sub-1%)
-         * Bit7:    MCU WDT reset
-         * Bit6:    Shell opened (GPIO1_0 1->0)
-         * Bit5:    Shell closed (GPIO1_0 0->1)
-         * Bit1:    Power button held
-         * Bit0:    Power button pressed
-         */
-
-        // Ignore "shell opened", just ack
-        u32 mcuInts = mcuGetPendingInterrupts(MCU_INT_MASK_FOR_INPUT);
-
-        if (mcuInts & (BIT(7) | BIT(5) | BIT(1) | BIT(0)))
-            powerOff();
-
-        if (mcuInts & BIT(13))
-        {
-            u8 battLevelIntPart = I2C_readReg(I2C_DEV_MCU, 0xB);
-            if (battLevelIntPart == 0)
-                powerOff();
-        }
-
         key = HID_PAD;
 
         if(!key)
         {
+            if(shouldShellShutdown)
+            {
+                u8 shellState = I2C_readReg(I2C_DEV_MCU, 0xF);
+                wait(5);
+                if(!(shellState & 2)) mcuPowerOff();
+            }
+
+            u8 intStatus = I2C_readReg(I2C_DEV_MCU, 0x10);
+            wait(5);
+            if(intStatus & 1) mcuPowerOff(); //Power button pressed
+
             oldKey = 0;
             dPadDelay = 0;
             continue;
@@ -138,6 +113,20 @@ u32 waitInput(bool isMenu)
     return key;
 }
 
+void mcuPowerOff(void)
+{
+    if(!needToSetupScreens) clearScreens(false);
+
+    //Shutdown LCD
+    if(ARESCREENSINITIALIZED) I2C_writeReg(I2C_DEV_MCU, 0x22, 1 << 0);
+
+    //Ensure that all memory transfers have completed and that the data cache has been flushed
+    flushEntireDCache();
+
+    I2C_writeReg(I2C_DEV_MCU, 0x20, 1 << 0);
+    while(true);
+}
+
 void wait(u64 amount)
 {
     startChrono();
@@ -162,5 +151,6 @@ void error(const char *fmt, ...)
     drawString(true, 10, posY + 2 * SPACING_Y, COLOR_WHITE, "Press any button to shutdown");
 
     waitInput(false);
-    powerOff();
+
+    mcuPowerOff();
 }
diff --git a/arm9/source/utils.h b/arm9/source/utils.h
index 862310271..83bf7ea50 100644
--- a/arm9/source/utils.h
+++ b/arm9/source/utils.h
@@ -39,7 +39,7 @@
 #define MAKE_BRANCH(src,dst)      (0xEA000000 | ((u32)((((u8 *)(dst) - (u8 *)(src)) >> 2) - 2) & 0xFFFFFF))
 #define MAKE_BRANCH_LINK(src,dst) (0xEB000000 | ((u32)((((u8 *)(dst) - (u8 *)(src)) >> 2) - 2) & 0xFFFFFF))
 
-void NORETURN powerOff(void);
 u32 waitInput(bool isMenu);
+void mcuPowerOff(void);
 void wait(u64 amount);
-void NORETURN error(const char *fmt, ...);
+void error(const char *fmt, ...);