diff --git a/Core/Inc/FreeRTOSConfig.h b/Core/Inc/FreeRTOSConfig.h
index 98d95a1..ea38632 100644
--- a/Core/Inc/FreeRTOSConfig.h
+++ b/Core/Inc/FreeRTOSConfig.h
@@ -133,7 +133,8 @@ See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html. */
 /* Normal assert() semantics without relying on the provision of an assert.h
 header file. */
 /* USER CODE BEGIN 1 */
-#define configASSERT( x ) if ((x) == 0) {taskDISABLE_INTERRUPTS(); for( ;; );}
+#include <stdio.h>
+#define configASSERT( x ) if ((x) == 0) {taskDISABLE_INTERRUPTS(); printf("configASSERT "__FILE__":%d\r\n",__LINE__); for( ;; );}
 /* USER CODE END 1 */
 
 /* Definitions that map the FreeRTOS port interrupt handlers to their CMSIS
diff --git a/Core/Src/app_main.c b/Core/Src/app_main.c
index 8884f65..d825a32 100644
--- a/Core/Src/app_main.c
+++ b/Core/Src/app_main.c
@@ -83,6 +83,7 @@ static void redraw_display() {
 
 void app_task_main(void *argument)
 {
+    printf("Main task\r\n");
     app_analog_init();
     app_buzzer_init();
     app_knob_init();
@@ -97,6 +98,7 @@ void app_task_main(void *argument)
     bool any_change = true;
     uint32_t last_redraw = osKernelGetTickCount();
 
+    printf("Loop\r\n");
     for (;;) {
         // sampling is done in the heater loop
 
@@ -144,7 +146,7 @@ void app_task_main(void *argument)
             any_change = false;
 
             // Blink
-            HAL_GPIO_TogglePin(LED_GPIO_Port, LED_Pin);
+            LL_GPIO_TogglePin(LED_GPIO_Port, LED_Pin);
         }
 
         vTaskDelay(pdMS_TO_TICKS(10));
diff --git a/Core/Src/freertos.c b/Core/Src/freertos.c
index dfbacd0..aa4f7a8 100644
--- a/Core/Src/freertos.c
+++ b/Core/Src/freertos.c
@@ -135,6 +135,7 @@ void vApplicationMallocFailedHook(void);
 /* USER CODE BEGIN 4 */
 void vApplicationStackOverflowHook(xTaskHandle xTask, signed char *pcTaskName)
 {
+   printf("vApplicationStackOverflowHook\r\n");
    /* Run time stack overflow checking is performed if
    configCHECK_FOR_STACK_OVERFLOW is defined to 1 or 2. This hook function is
    called if a stack overflow is detected. */
@@ -144,6 +145,7 @@ void vApplicationStackOverflowHook(xTaskHandle xTask, signed char *pcTaskName)
 /* USER CODE BEGIN 5 */
 void vApplicationMallocFailedHook(void)
 {
+   printf("vApplicationMallocFailedHook\r\n");
    /* vApplicationMallocFailedHook() will only be called if
    configUSE_MALLOC_FAILED_HOOK is set to 1 in FreeRTOSConfig.h. It is a hook
    function that will get called if a call to pvPortMalloc() fails.
diff --git a/Core/Src/main.c b/Core/Src/main.c
index 1ca3e38..123994c 100644
--- a/Core/Src/main.c
+++ b/Core/Src/main.c
@@ -100,7 +100,7 @@ int main(void)
   MX_IWDG_Init();
   MX_USART1_UART_Init();
   MX_ADC1_Init();
-  MX_DMA_Init();
+//  MX_DMA_Init();
   MX_TIM4_Init();
   MX_TIM2_Init();
   MX_TIM3_Init();
@@ -110,6 +110,7 @@ int main(void)
   // this ensures SysTick runs at 1000Hz - used for LL delays
   LL_Init1msTick(SystemCoreClock);
 
+  printf("Start.\r\n");
   /* USER CODE END 2 */
 
   /* Init scheduler */
@@ -117,6 +118,7 @@ int main(void)
   MX_FREERTOS_Init();
 
   /* Start scheduler */
+  printf("a\r\n");
   osKernelStart();
 
   /* We should never get here as control is now taken by the scheduler */
@@ -218,6 +220,7 @@ void Error_Handler(void)
   /* USER CODE BEGIN Error_Handler_Debug */
   /* User can add his own implementation to report the HAL error return state */
   __disable_irq();
+    printf("Error_Handler\r\n");
   while (1)
   {
   }
@@ -234,6 +237,7 @@ void Error_Handler(void)
   */
 void assert_failed(uint8_t *file, uint32_t line)
 {
+    printf("assert_failed\r\n");
   /* USER CODE BEGIN 6 */
   /* User can add his own implementation to report the file name and line number,
      ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
diff --git a/Core/Src/stm32f1xx_it.c b/Core/Src/stm32f1xx_it.c
index 00ae483..78a4a35 100644
--- a/Core/Src/stm32f1xx_it.c
+++ b/Core/Src/stm32f1xx_it.c
@@ -103,6 +103,7 @@ void HardFault_Handler(void)
 void MemManage_Handler(void)
 {
   /* USER CODE BEGIN MemoryManagement_IRQn 0 */
+    printf("MemManage_Handler\r\n");
 
   /* USER CODE END MemoryManagement_IRQn 0 */
   while (1)
@@ -118,6 +119,7 @@ void MemManage_Handler(void)
 void BusFault_Handler(void)
 {
   /* USER CODE BEGIN BusFault_IRQn 0 */
+    printf("BusFault_Handler\r\n");
 
   /* USER CODE END BusFault_IRQn 0 */
   while (1)
@@ -133,6 +135,7 @@ void BusFault_Handler(void)
 void UsageFault_Handler(void)
 {
   /* USER CODE BEGIN UsageFault_IRQn 0 */
+    printf("UsageFault_Handler\r\n");
 
   /* USER CODE END UsageFault_IRQn 0 */
   while (1)
diff --git a/Core/Src/usart.c b/Core/Src/usart.c
index 9166098..547bdba 100644
--- a/Core/Src/usart.c
+++ b/Core/Src/usart.c
@@ -83,8 +83,8 @@ void MX_USART1_UART_Init(void)
 int _write(int fd, const char *pcBuffer, const int iLength) {
     int cnt = iLength;
     while (cnt-- > 0) {
-        LL_USART_TransmitData8(USART_DEBUG, *pcBuffer++);
         while (!LL_USART_IsActiveFlag_TXE(USART_DEBUG)) {}
+        LL_USART_TransmitData8(USART_DEBUG, *pcBuffer++);
     }
     return iLength;
 }