diff --git a/Core/Inc/FreeRTOSConfig.h b/Core/Inc/FreeRTOSConfig.h
index 1d62fa6..c5d7835 100644
--- a/Core/Inc/FreeRTOSConfig.h
+++ b/Core/Inc/FreeRTOSConfig.h
@@ -138,7 +138,7 @@ See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html. */
 header file. */
 /* USER CODE BEGIN 1 */
 #include "snprintf.h"
-#define configASSERT( x ) if ((x) == 0) {taskDISABLE_INTERRUPTS(); PRINTF("configASSERT "__FILE__":%d\r\n",__LINE__); for( ;; );}
+#define configASSERT( x ) if ((x) == 0) {taskDISABLE_INTERRUPTS(); PRINTF("FreeRTOS assert @ %s:%d\r\n", __FILE__, __LINE__); for( ;; );}
 /* USER CODE END 1 */
 
 /* Definitions that map the FreeRTOS port interrupt handlers to their CMSIS
diff --git a/Core/Inc/main.h b/Core/Inc/main.h
index 77d75cc..a1f5c4d 100644
--- a/Core/Inc/main.h
+++ b/Core/Inc/main.h
@@ -16,10 +16,6 @@
   *
   ******************************************************************************
   */
-// this is a hack needed for CLion - placed here so cubemx does not overwrite it
-#ifndef USE_FULL_LL_DRIVER
-#define USE_FULL_LL_DRIVER 1
-#endif
 /* USER CODE END Header */
 
 /* Define to prevent recursive inclusion -------------------------------------*/
diff --git a/Core/Src/app_main.c b/Core/Src/app_main.c
index 73786af..c7d180e 100644
--- a/Core/Src/app_main.c
+++ b/Core/Src/app_main.c
@@ -33,13 +33,13 @@ static void redraw_display() {
 
     char tmp[100];
 
-    PRINTF(tmp, "T=%d°C", (int) s_app.oven_temp);
+    SPRINTF(tmp, "T=%d°C", (int) s_app.oven_temp);
     fb_text(3, 3, tmp, FONT_5X7, 1);
 
-    PRINTF(tmp, "Cil=%d°C", s_app.set_temp);
+    SPRINTF(tmp, "Cil=%d°C", s_app.set_temp);
     fb_text(3, 11, tmp, FONT_5X7, 1);
 
-    PRINTF(tmp, "Stav=%s", s_app.run ? "ZAP" : "VYP");
+    SPRINTF(tmp, "Stav=%s", s_app.run ? "ZAP" : "VYP");
     fb_text(3, 19, tmp, FONT_5X7, 1);
 
     if (s_app.run) {
@@ -141,6 +141,8 @@ void app_task_main(void *argument)
 
         uint32_t now = osKernelGetTickCount();
         if (any_change || (now - last_redraw > pdMS_TO_TICKS(500))) {
+            PUTS("Cycle\r\n");
+            PRINTF("test printf\r\n");
             last_redraw = now;
             redraw_display();
             any_change = false;
diff --git a/Core/Src/uart_stdout.c b/Core/Src/uart_stdout.c
new file mode 100644
index 0000000..dba7b67
--- /dev/null
+++ b/Core/Src/uart_stdout.c
@@ -0,0 +1,52 @@
+/**
+ * TODO file description
+ */
+
+#include <string.h>
+#include "uart_stdout.h"
+#include "FreeRTOS.h"
+#include "main.h"
+
+#define USE_CRITICAL 0
+
+void stdout_putchar(char c) {
+#if USE_CRITICAL
+    portENTER_CRITICAL();
+#endif
+    while (!LL_USART_IsActiveFlag_TXE(USART_DEBUG)) {}
+    LL_USART_TransmitData8(USART_DEBUG, c);
+    while (!LL_USART_IsActiveFlag_TC(USART_DEBUG)) {}
+#if USE_CRITICAL
+    portEXIT_CRITICAL();
+#endif
+}
+
+void stdout_write(const char *pcBuffer, const size_t iLength) {
+#if USE_CRITICAL
+    portENTER_CRITICAL();
+#endif
+    while (!LL_USART_IsActiveFlag_TXE(USART_DEBUG)) {}
+    int cnt = (int) iLength;
+    while (cnt-- > 0) {
+        char c = *pcBuffer++;
+        LL_USART_TransmitData8(USART_DEBUG, c);
+        while (!LL_USART_IsActiveFlag_TC(USART_DEBUG)) {}
+    }
+#if USE_CRITICAL
+    portEXIT_CRITICAL();
+#endif
+}
+
+void stdout_puts(const char *pcBuffer) {
+    stdout_write(pcBuffer, strlen(pcBuffer));
+}
+
+/**
+  * @brief  Retargets the C library printf function to the USART.
+  * @param  None
+  * @retval None
+  */
+int _write(int fd, const char *pcBuffer, const int iLength) {
+    stdout_write(pcBuffer, iLength);
+    return iLength;
+}
diff --git a/Core/Src/uart_stdout.h b/Core/Src/uart_stdout.h
new file mode 100644
index 0000000..9e6af06
--- /dev/null
+++ b/Core/Src/uart_stdout.h
@@ -0,0 +1,8 @@
+/**
+ * TODO file description
+ */
+
+#ifndef BLUEPILLTROUBA_UART_STDOUT_H
+#define BLUEPILLTROUBA_UART_STDOUT_H
+
+#endif //BLUEPILLTROUBA_UART_STDOUT_H
diff --git a/Core/Src/usart.c b/Core/Src/usart.c
index 3194fea..1b06fd3 100644
--- a/Core/Src/usart.c
+++ b/Core/Src/usart.c
@@ -21,9 +21,6 @@
 #include "usart.h"
 
 /* USER CODE BEGIN 0 */
-#include <stddef.h>
-#include <string.h>
-#include "main.h"
 /* USER CODE END 0 */
 
 /* USART1 init function */
@@ -76,32 +73,6 @@ void MX_USART1_UART_Init(void)
 
 }
 
-/* USER CODE BEGIN 1 */
-void stdout_write(const char *pcBuffer, const size_t iLength) {
-    int cnt = (int) iLength;
-    while (cnt-- > 0) {
-        while (!LL_USART_IsActiveFlag_TXE(USART_DEBUG)) {}
-        LL_USART_TransmitData8(USART_DEBUG, *pcBuffer++);
-    }
-}
-
-void stdout_puts(const char *pcBuffer) {
-    stdout_write(pcBuffer, strlen(pcBuffer));
-}
-
-void stdout_putchar(char c) {
-    while (!LL_USART_IsActiveFlag_TXE(USART_DEBUG)) {}
-    LL_USART_TransmitData8(USART_DEBUG, c);
-}
-
-/**
-  * @brief  Retargets the C library printf function to the USART.
-  * @param  None
-  * @retval None
-  */
-int _write(int fd, const char *pcBuffer, const int iLength) {
-    stdout_write(pcBuffer, iLength);
-    return iLength;
-}
 
+/* USER CODE BEGIN 1 */
 /* USER CODE END 1 */
diff --git a/Lib/snprintf/snprintf.c b/Lib/snprintf/snprintf.c
index d924fc5..fdf59c9 100644
--- a/Lib/snprintf/snprintf.c
+++ b/Lib/snprintf/snprintf.c
@@ -831,11 +831,13 @@ int vasprintf(char **ptr, const char *format, va_list ap)
 {
     int ret;
 
+    va_list ap_copy;
+    va_copy(ap_copy, ap);
     ret = vsnprintf((char *) NULL, 0, format, ap);
     if (ret + 1 <= 1) { return ret; } /* pts: bit of old unsigned trick... */
 
     if (NULL == (*ptr = (char *) my_malloc(ret + 1))) { return -1; }
-    ret = vsnprintf(*ptr, ret + 1, format, ap);
+    ret = vsnprintf(*ptr, ret + 1, format, ap_copy);
 
     return ret;
 }
diff --git a/Lib/snprintf/snprintf.h b/Lib/snprintf/snprintf.h
index 365df00..fdd7c85 100644
--- a/Lib/snprintf/snprintf.h
+++ b/Lib/snprintf/snprintf.h
@@ -26,6 +26,11 @@ int fixup_vprintf(const char *format, va_list ap);
 #define PRINTF(...)    fixup_printf(__VA_ARGS__)
 #define VPRINTF(...)   fixup_vprintf(__VA_ARGS__)
 
+// for debug
+//#include <stdio.h>
+//#define PRINTF(...)    printf(__VA_ARGS__)
+//#define SPRINTF(...)   sprintf(__VA_ARGS__)
+
 // extern
 
 extern void stdout_puts(const char *s);
diff --git a/Makefile b/Makefile
index 05e738f..4e950c1 100644
--- a/Makefile
+++ b/Makefile
@@ -52,6 +52,7 @@ Core/Src/app_temp.c \
 Core/Src/app_knob.c \
 Core/Src/app_buzzer.c \
 Core/Src/app_heater.c \
+Core/Src/uart_stdout.c \
 Core/Src/stm32f1xx_it.c \
 Core/Src/system_stm32f1xx.c \
 Middlewares/Third_Party/FreeRTOS/Source/croutine.c \
diff --git a/STM32F103C8Tx_FLASH.ld b/STM32F103C8Tx_FLASH.ld
index e35e3ea..3850058 100644
--- a/STM32F103C8Tx_FLASH.ld
+++ b/STM32F103C8Tx_FLASH.ld
@@ -62,8 +62,8 @@ _Min_Stack_Size = 0x400; /* required amount of stack */
 MEMORY
 {
 RAM (xrw)      : ORIGIN = 0x20000000, LENGTH = 20K
-FLASH (rx)      : ORIGIN = 0x8000000, LENGTH = 48K
-EEPROM_EMU (rx)      : ORIGIN = ORIGIN(FLASH) + LENGTH(FLASH), LENGTH = 16K
+FLASH (rx)      : ORIGIN = 0x8000000, LENGTH = 56K
+EEPROM_EMU (rx)      : ORIGIN = ORIGIN(FLASH) + LENGTH(FLASH), LENGTH = 8K
 }
 
 /* Define output sections */
@@ -135,7 +135,7 @@ SECTIONS
   _sidata = LOADADDR(.data);
 
   /* Initialized data sections goes into RAM, load LMA copy after code */
-  .data : 
+  .data :
   {
     . = ALIGN(4);
     _sdata = .;        /* create a global symbol at data start */
@@ -146,7 +146,7 @@ SECTIONS
     _edata = .;        /* define a global symbol at data end */
   } >RAM AT> FLASH
 
-  
+
   /* Uninitialized data section */
   . = ALIGN(4);
   .bss :
@@ -174,7 +174,7 @@ SECTIONS
     . = ALIGN(8);
   } >RAM
 
-  
+
 
   /* Remove information from the standard libraries */
   /DISCARD/ :