diff --git a/Core/Inc/main.h b/Core/Inc/main.h
index afe90eb..2596a38 100644
--- a/Core/Inc/main.h
+++ b/Core/Inc/main.h
@@ -62,6 +62,7 @@ void Error_Handler(void);
 #define LED1_GPIO_Port GPIOA
 #define SPI2_BUSY_Pin GPIO_PIN_0
 #define SPI2_BUSY_GPIO_Port GPIOB
+#define SPI2_BUSY_EXTI_IRQn EXTI0_IRQn
 #define SPI2_RES_Pin GPIO_PIN_1
 #define SPI2_RES_GPIO_Port GPIOB
 #define SPI2_DC_Pin GPIO_PIN_14
diff --git a/Core/Inc/stm32h7xx_it.h b/Core/Inc/stm32h7xx_it.h
index 112311d..faa8c15 100644
--- a/Core/Inc/stm32h7xx_it.h
+++ b/Core/Inc/stm32h7xx_it.h
@@ -56,6 +56,7 @@ void DebugMon_Handler(void);
 void PVD_AVD_IRQHandler(void);
 void FLASH_IRQHandler(void);
 void RCC_IRQHandler(void);
+void EXTI0_IRQHandler(void);
 void SPI2_IRQHandler(void);
 void TIM7_IRQHandler(void);
 void FPU_IRQHandler(void);
diff --git a/Core/Src/main.c b/Core/Src/main.c
index 136e5e8..a503844 100644
--- a/Core/Src/main.c
+++ b/Core/Src/main.c
@@ -402,7 +402,7 @@ static void MX_GPIO_Init(void)
 
   /*Configure GPIO pin : SPI2_BUSY_Pin */
   GPIO_InitStruct.Pin = SPI2_BUSY_Pin;
-  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
+  GPIO_InitStruct.Mode = GPIO_MODE_IT_FALLING;
   GPIO_InitStruct.Pull = GPIO_NOPULL;
   HAL_GPIO_Init(SPI2_BUSY_GPIO_Port, &GPIO_InitStruct);
 
@@ -420,6 +420,10 @@ static void MX_GPIO_Init(void)
   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
   HAL_GPIO_Init(SPI2_DC_GPIO_Port, &GPIO_InitStruct);
 
+  /* EXTI interrupt init*/
+  HAL_NVIC_SetPriority(EXTI0_IRQn, 5, 0);
+  HAL_NVIC_EnableIRQ(EXTI0_IRQn);
+
 }
 
 /* USER CODE BEGIN 4 */
diff --git a/Core/Src/stm32h7xx_it.c b/Core/Src/stm32h7xx_it.c
index 34e397b..a4c2578 100644
--- a/Core/Src/stm32h7xx_it.c
+++ b/Core/Src/stm32h7xx_it.c
@@ -204,6 +204,20 @@ void RCC_IRQHandler(void)
   /* USER CODE END RCC_IRQn 1 */
 }
 
+/**
+  * @brief This function handles EXTI line0 interrupt.
+  */
+void EXTI0_IRQHandler(void)
+{
+  /* USER CODE BEGIN EXTI0_IRQn 0 */
+
+  /* USER CODE END EXTI0_IRQn 0 */
+  HAL_GPIO_EXTI_IRQHandler(GPIO_PIN_0);
+  /* USER CODE BEGIN EXTI0_IRQn 1 */
+
+  /* USER CODE END EXTI0_IRQn 1 */
+}
+
 /**
   * @brief This function handles SPI2 global interrupt.
   */
diff --git a/Core/Src/user_epd_impl.c b/Core/Src/user_epd_impl.c
index a0f147b..3eb5739 100644
--- a/Core/Src/user_epd_impl.c
+++ b/Core/Src/user_epd_impl.c
@@ -4,59 +4,68 @@
 
 #include "user_epd_impl.h"
 
+#define BUSY_MAX_POLLING_TIME 30000 // 30s
+
+uint8_t g_epd_busy_irq_flag = 0;
+
+extern osSemaphoreId_t g_epd_busy_semphr;
 
 depg0213_ret_t _epd_reset_cb(void *handle) {
-  SPI_HandleTypeDef *hspi = handle;
-  if(hspi->Instance == SPI2) {
-    HAL_GPIO_WritePin(SPI2_RES_GPIO_Port, SPI2_RES_Pin, GPIO_PIN_SET);
-    HAL_Delay(10);
-    HAL_GPIO_WritePin(SPI2_RES_GPIO_Port, SPI2_RES_Pin, GPIO_PIN_RESET);
-    HAL_Delay(5);
-    HAL_GPIO_WritePin(SPI2_RES_GPIO_Port, SPI2_RES_Pin, GPIO_PIN_SET);
-    HAL_Delay(10);
-  }
-  return DEPG0213_OK;
+    SPI_HandleTypeDef *hspi = handle;
+    if (hspi->Instance == SPI2) {
+        HAL_GPIO_WritePin(SPI2_RES_GPIO_Port, SPI2_RES_Pin, GPIO_PIN_RESET);
+        HAL_Delay(5);
+        HAL_GPIO_WritePin(SPI2_RES_GPIO_Port, SPI2_RES_Pin, GPIO_PIN_SET);
+    }
+    return DEPG0213_OK;
 }
 
 depg0213_ret_t _epd_poll_busy(void *handle) {
-  SPI_HandleTypeDef *hspi = handle;
-  if(hspi->Instance == SPI2) {
-    uint32_t tick_start = HAL_GetTick();
-    while (HAL_GPIO_ReadPin(SPI2_BUSY_GPIO_Port, SPI2_BUSY_Pin) == GPIO_PIN_SET) {
-      if(HAL_GetTick() - tick_start > 10000) {
-        return DEPG0213_ERROR;
-      }
+    SPI_HandleTypeDef *hspi = handle;
+    if (hspi->Instance == SPI2) {
+        if (osKernelGetState() != osKernelRunning) { // Kernel has not started, use flag polling instead.
+            uint32_t tick_start = HAL_GetTick();
+            while (!g_epd_busy_irq_flag) {
+                if (HAL_GetTick() - tick_start > BUSY_MAX_POLLING_TIME) {
+                    return DEPG0213_ERROR;
+                }
+            }
+            g_epd_busy_irq_flag = 0;
+        } else { // Kernel has started, use semaphore.
+            if(osSemaphoreAcquire(g_epd_busy_semphr, BUSY_MAX_POLLING_TIME) != osOK) {
+                return DEPG0213_ERROR;
+            }
+        }
     }
-  }
-  return DEPG0213_OK;
+    return DEPG0213_OK;
 }
 
 depg0213_ret_t _epd_write_cmd_cb(void *handle, uint8_t *cmd, uint8_t len) {
-  SPI_HandleTypeDef *hspi = handle;
+    SPI_HandleTypeDef *hspi = handle;
 
-  HAL_StatusTypeDef ret = HAL_OK;
+    HAL_StatusTypeDef ret = HAL_OK;
 
-  if(hspi->Instance == SPI2) {
-    HAL_GPIO_WritePin(SPI2_DC_GPIO_Port, SPI2_DC_Pin, GPIO_PIN_RESET);
-    ret = HAL_SPI_Transmit(hspi, cmd, 0x01, 1000);
-    if(len > 1) {
-      HAL_GPIO_WritePin(SPI2_DC_GPIO_Port, SPI2_DC_Pin, GPIO_PIN_SET);
-      ret = HAL_SPI_Transmit(hspi, &cmd[1], len - 1, 1000);
+    if (hspi->Instance == SPI2) {
+        HAL_GPIO_WritePin(SPI2_DC_GPIO_Port, SPI2_DC_Pin, GPIO_PIN_RESET);
+        ret = HAL_SPI_Transmit(hspi, cmd, 0x01, 1000);
+        if (len > 1) {
+            HAL_GPIO_WritePin(SPI2_DC_GPIO_Port, SPI2_DC_Pin, GPIO_PIN_SET);
+            ret = HAL_SPI_Transmit(hspi, &cmd[1], len - 1, 1000);
+        }
     }
-  }
-  if(ret != HAL_OK) return DEPG0213_ERROR;
-  return DEPG0213_OK;
+    if (ret != HAL_OK) return DEPG0213_ERROR;
+    return DEPG0213_OK;
 }
 
 depg0213_ret_t _epd_write_data_cb(void *handle, uint8_t *data, uint16_t len) {
-  SPI_HandleTypeDef *hspi = handle;
+    SPI_HandleTypeDef *hspi = handle;
 
-  HAL_StatusTypeDef ret = HAL_OK;
+    HAL_StatusTypeDef ret = HAL_OK;
 
-  if(hspi->Instance == SPI2) {
-    HAL_GPIO_WritePin(SPI2_DC_GPIO_Port, SPI2_DC_Pin, GPIO_PIN_SET);
-    ret = HAL_SPI_Transmit(hspi, data, len, 1000);
-  }
-  if(ret != HAL_OK) return DEPG0213_ERROR;
-  return DEPG0213_OK;
+    if (hspi->Instance == SPI2) {
+        HAL_GPIO_WritePin(SPI2_DC_GPIO_Port, SPI2_DC_Pin, GPIO_PIN_SET);
+        ret = HAL_SPI_Transmit(hspi, data, len, 1000);
+    }
+    if (ret != HAL_OK) return DEPG0213_ERROR;
+    return DEPG0213_OK;
 }
\ No newline at end of file
diff --git a/Core/Src/user_irq_handlers.c b/Core/Src/user_irq_handlers.c
new file mode 100644
index 0000000..13ba7c4
--- /dev/null
+++ b/Core/Src/user_irq_handlers.c
@@ -0,0 +1,21 @@
+#include "cmsis_os2.h"
+
+#include "main.h"
+
+#include "user_epd_impl.h"
+
+extern uint8_t g_epd_busy_irq_flag;
+extern osSemaphoreId_t g_epd_busy_semphr;
+
+void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin) {
+    // FIXME
+    if(GPIO_Pin == SPI2_BUSY_Pin) {
+        if(osKernelGetState() != osKernelRunning) { // Kernel has not started, write poll variable
+            g_epd_busy_irq_flag = 1;
+        }
+        else { // Kernel has started, release semaphore.
+            osSemaphoreRelease(g_epd_busy_semphr);
+            // CMSIS-OS2 wraps FreeRTOS call, no need to use __xxFromISR functions here.
+        }
+    }
+}
\ No newline at end of file
diff --git a/Core/Src/user_tasks.c b/Core/Src/user_tasks.c
index e001b64..51c9458 100644
--- a/Core/Src/user_tasks.c
+++ b/Core/Src/user_tasks.c
@@ -1,3 +1,5 @@
+#include "cmsis_os2.h"
+
 #include "lvgl.h"
 
 #include "user_epd_impl.h"
@@ -5,33 +7,49 @@
 // Defined in main.c
 extern SPI_HandleTypeDef hspi2;
 
-// Globals
-depg0213_epd_t g_epd;
-
-// Private defines
-void _user_tasks_init_epd(void);
+// Private function prototypes
+uint8_t _user_tasks_init_epd(void);
 void _user_tasks_init_lvgl(void);
 
+// Globals
+depg0213_epd_t g_epd = {
+    .user_data = &hspi2,
+    .cb = {
+        .reset_cb = _epd_reset_cb,
+        .poll_busy_cb = _epd_poll_busy,
+        .write_cmd_cb = _epd_write_cmd_cb,
+        .write_data_cb = _epd_write_data_cb
+      }
+};
+osSemaphoreId_t g_epd_busy_semphr;
+
 void user_tasks_initialize(void) {
-    _user_tasks_init_epd();
+    if(_user_tasks_init_epd()) return;
     _user_tasks_init_lvgl();
 }
 
-void _user_tasks_init_epd(void) {
-    depg0213_epd_t epd = {
-    .user_data = &hspi2,
-    .cb = {
-      .reset_cb = _epd_reset_cb,
-      .poll_busy_cb = _epd_poll_busy,
-      .write_cmd_cb = _epd_write_cmd_cb,
-      .write_data_cb = _epd_write_data_cb
+void user_task_flush_epd(void *arguments) {
+    for(;;) {
+        //
     }
-  };
+}
 
-  depg0213_epd_init(&epd);
+uint8_t _user_tasks_init_epd(void) {
+    depg0213_ret_t ret;
 
-  depg0213_epd_direction(&epd, DEPG0213_HORIZONTAL_INVERSE);
-  depg0213_epd_deepsleep(&epd);
+    g_epd_busy_semphr = osSemaphoreNew(1U, 0U, NULL); // Max: 1, initial 1, attr NULL
+  if(g_epd_busy_semphr == NULL) return -1;
+
+    ret = depg0213_epd_init(&g_epd);
+    if(ret != DEPG0213_OK) return -2;
+
+    ret = depg0213_epd_direction(&g_epd, DEPG0213_HORIZONTAL_INVERSE);
+    if(ret != DEPG0213_OK) return -3;
+
+    ret = depg0213_epd_deepsleep(&g_epd);
+    if(ret != DEPG0213_OK) return -4;
+
+    return 0;
 }
 
 void _user_tasks_init_lvgl(void) {
diff --git a/Makefile b/Makefile
index d059c2e..7c439af 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 ##########################################################################################################################
-# File automatically-generated by tool: [projectgenerator] version: [3.11.2] date: [Mon Jan 11 00:59:29 CST 2021] 
+# File automatically-generated by tool: [projectgenerator] version: [3.11.2] date: [Wed Jan 13 02:55:23 CST 2021] 
 ##########################################################################################################################
 
 # ------------------------------------------------
@@ -41,6 +41,7 @@ Core/Src/stm32h7xx_it.c \
 Core/Src/stm32h7xx_hal_msp.c \
 Core/Src/user_epd_impl.c \
 Core/Src/user_tasks.c \
+Core/Src/user_irq_handlers.c \
 Drivers/STM32H7xx_HAL_Driver/Src/stm32h7xx_hal_cortex.c \
 Drivers/STM32H7xx_HAL_Driver/Src/stm32h7xx_hal_tim.c \
 Drivers/STM32H7xx_HAL_Driver/Src/stm32h7xx_hal_tim_ex.c \
diff --git a/STM32H750_EPD.ioc b/STM32H750_EPD.ioc
index dd3b162..a380e5a 100644
--- a/STM32H750_EPD.ioc
+++ b/STM32H750_EPD.ioc
@@ -82,10 +82,11 @@ CORTEX_M7.Size-Cortex_Memory_Protection_Unit_Region2_Settings=MPU_REGION_SIZE_12
 NVIC.SysTick_IRQn=true\:15\:0\:false\:false\:false\:true\:false\:true
 RCC.DIVM1=4
 RCC.RTCClockSelection=RCC_RTCCLKSOURCE_LSE
+PB0.GPIO_ModeDefaultEXTI=GPIO_MODE_IT_FALLING
 ProjectManager.FirmwarePackage=STM32Cube FW_H7 V1.8.0
 MxDb.Version=DB.6.0.10
 CORTEX_M7.IsCacheable-Cortex_Memory_Protection_Unit_Region2_Settings=MPU_ACCESS_CACHEABLE
-PB0.GPIOParameters=GPIO_Label
+PB0.GPIOParameters=GPIO_Label,GPIO_ModeDefaultEXTI
 RCC.DIVP1Freq_Value=240000000
 PA1.GPIOParameters=GPIO_Label
 CORTEX_M7.TypeExtField-Cortex_Memory_Protection_Unit_Region2_Settings=MPU_TEX_LEVEL1
@@ -98,7 +99,7 @@ File.Version=6
 SPI2.CalculateBaudRate=15.0 MBits/s
 PE2.Signal=QUADSPI_BK1_IO2
 PA14\ (JTCK/SWCLK).Mode=Serial_Wire
-NVIC.SPI2_IRQn=true\:5\:0\:false\:false\:true\:true\:true\:true
+NVIC.SPI2_IRQn=true\:5\:0\:true\:false\:true\:true\:true\:true
 PB6.Locked=true
 NVIC.PendSV_IRQn=true\:15\:0\:false\:false\:false\:true\:false\:false
 RCC.DIVR2Freq_Value=16125000
@@ -120,6 +121,7 @@ CORTEX_M7.BaseAddress-Cortex_Memory_Protection_Unit_Region1_Settings=0x90000000
 RCC.EnbaleCSS=true
 PD12.Signal=QUADSPI_BK1_IO1
 ProjectManager.ToolChainLocation=
+SH.GPXTI0.0=GPIO_EXTI0
 NVIC.TimeBaseIP=TIM7
 RCC.DFSDMFreq_Value=120000000
 RCC.DIVR1Freq_Value=240000000
@@ -146,7 +148,7 @@ PB15.Locked=true
 RCC.VCO3OutputFreq_Value=32250000
 VP_RTC_VS_RTC_Activate.Signal=RTC_VS_RTC_Activate
 RCC.PLLSourceVirtual=RCC_PLLSOURCE_HSE
-NVIC.QUADSPI_IRQn=true\:5\:0\:false\:false\:true\:true\:true\:true
+NVIC.QUADSPI_IRQn=true\:5\:0\:true\:false\:true\:true\:true\:true
 ProjectManager.ProjectFileName=STM32H750_EPD.ioc
 CORTEX_M7.CPU_ICache=Enabled
 RCC.DIVQ1=8
@@ -161,6 +163,7 @@ RCC.SWPMI1Freq_Value=120000000
 CORTEX_M7.IsCacheable-Cortex_Memory_Protection_Unit_Region0_Settings=MPU_ACCESS_NOT_CACHEABLE
 RCC.SAI4BFreq_Value=60000000
 SPI2.NSSPMode=SPI_NSS_PULSE_ENABLE
+SH.GPXTI0.ConfNb=1
 ProjectManager.DefaultFWLocation=true
 ProjectManager.DeletePrevious=true
 PB14.Locked=true
@@ -189,7 +192,7 @@ PA1.Signal=GPIO_Output
 RCC.CKPERFreq_Value=64000000
 PB1.Locked=true
 PB14.Signal=GPIO_Output
-NVIC.PVD_AVD_IRQn=true\:5\:0\:false\:false\:true\:true\:true\:true
+NVIC.PVD_AVD_IRQn=true\:5\:0\:true\:false\:true\:true\:true\:true
 CORTEX_M7.Enable-Cortex_Memory_Protection_Unit_Region2_Settings=MPU_REGION_ENABLE
 board=custom
 ProjectManager.LastFirmware=true
@@ -207,7 +210,7 @@ RCC.ADCFreq_Value=16125000
 PA1.GPIO_Label=LED1
 CORTEX_M7.AccessPermission-Cortex_Memory_Protection_Unit_Region0_Settings=MPU_REGION_FULL_ACCESS
 NVIC.NonMaskableInt_IRQn=true\:0\:0\:false\:false\:true\:false\:false\:true
-NVIC.HSEM1_IRQn=true\:5\:0\:false\:false\:true\:true\:true\:true
+NVIC.HSEM1_IRQn=true\:5\:0\:true\:false\:true\:true\:true\:true
 ProjectManager.FreePins=false
 RCC.IPParameters=ADCFreq_Value,AHB12Freq_Value,AHB4Freq_Value,APB1Freq_Value,APB2Freq_Value,APB3Freq_Value,APB4Freq_Value,AXIClockFreq_Value,CECFreq_Value,CKPERFreq_Value,CortexFreq_Value,CpuClockFreq_Value,D1CPREFreq_Value,DFSDMACLkFreq_Value,DFSDMFreq_Value,DIVM1,DIVN1,DIVP1Freq_Value,DIVP2Freq_Value,DIVP3Freq_Value,DIVQ1,DIVQ1Freq_Value,DIVQ2Freq_Value,DIVQ3Freq_Value,DIVR1Freq_Value,DIVR2Freq_Value,DIVR3Freq_Value,EnbaleCSS,FDCANFreq_Value,FMCFreq_Value,FamilyName,HCLK3ClockFreq_Value,HCLKFreq_Value,HPRE,HRTIMFreq_Value,HSE_VALUE,I2C123Freq_Value,I2C4Freq_Value,LPTIM1Freq_Value,LPTIM2Freq_Value,LPTIM345Freq_Value,LPUART1Freq_Value,LSE_Drive_Capability,LTDCFreq_Value,MCO1PinFreq_Value,MCO2PinFreq_Value,PLLSourceVirtual,QSPICLockSelection,QSPIFreq_Value,RNGFreq_Value,RTCClockSelection,RTCFreq_Value,SAI1Freq_Value,SAI23Freq_Value,SAI4AFreq_Value,SAI4BFreq_Value,SDMMCFreq_Value,SPDIFRXFreq_Value,SPI123Freq_Value,SPI45Freq_Value,SPI6Freq_Value,SWPMI1Freq_Value,SYSCLKFreq_VALUE,SYSCLKSource,Tim1OutputFreq_Value,Tim2OutputFreq_Value,TraceFreq_Value,USART16Freq_Value,USART234578Freq_Value,USBFreq_Value,VCO1OutputFreq_Value,VCO2OutputFreq_Value,VCO3OutputFreq_Value,VCOInput1Freq_Value,VCOInput2Freq_Value,VCOInput3Freq_Value
 ProjectManager.AskForMigrate=true
@@ -224,6 +227,7 @@ VP_FREERTOS_VS_CMSIS_V2.Signal=FREERTOS_VS_CMSIS_V2
 Mcu.IP6=RTC
 Mcu.IP7=SPI2
 ProjectManager.CoupleFile=false
+NVIC.EXTI0_IRQn=true\:5\:0\:true\:false\:true\:true\:true\:true
 RCC.SYSCLKFreq_VALUE=240000000
 RCC.I2C123Freq_Value=120000000
 PA1.Locked=true
@@ -258,7 +262,7 @@ Mcu.Pin11=PB14
 Mcu.Pin12=PB15
 Mcu.Pin10=PB13
 RCC.DIVQ1Freq_Value=60000000
-NVIC.FPU_IRQn=true\:5\:0\:false\:false\:true\:true\:true\:false
+NVIC.FPU_IRQn=true\:5\:0\:true\:false\:true\:true\:true\:false
 SPI2.DataSize=SPI_DATASIZE_8BIT
 CORTEX_M7.CPU_DCache=Enabled
 PB1.GPIO_ModeDefaultOutputPP=GPIO_MODE_OUTPUT_OD
@@ -266,7 +270,7 @@ RCC.HCLK3ClockFreq_Value=120000000
 PB12.GPIO_PuPd=GPIO_PULLUP
 RCC.VCOInput2Freq_Value=250000
 RCC.APB1Freq_Value=120000000
-PB0.Signal=GPIO_Input
+PB0.Signal=GPXTI0
 ProjectManager.DeviceId=STM32H750VBTx
 PB12.GPIOParameters=GPIO_PuPd
 PB12.Signal=SPI2_NSS