diff --git a/CMakeLists.txt b/CMakeLists.txt
index 18d7cfc..2175ec2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,7 +21,7 @@ add_compile_options(-mcpu=${MCPU} -mthumb -mthumb-interwork)
 add_compile_options(-ffunction-sections -fdata-sections -fno-common -fmessage-length=0)
 
 add_definitions(-DSTM32F439xx)
-add_compile_definitions(HSE_VALUE=8000000)
+add_definitions(-DHSE_VALUE=8000000)
 
 include_directories(
     ${PROJECT_SOURCE_DIR}/bsp
@@ -46,6 +46,8 @@ file(GLOB_RECURSE SOURCES
 set(LINKER_SCRIPT ${PROJECT_SOURCE_DIR}/stm32_flash.ld)
 
 add_link_options(-specs=nosys.specs)
+add_link_options(-specs=nano.specs)
+add_link_options(-u _printf_float)
 add_link_options(-Wl,-gc-sections,--print-memory-usage,-Map=${PROJECT_BINARY_DIR}/${PROJECT_NAME}.map)
 add_link_options(-mcpu=${MCPU} -mthumb -mthumb-interwork)
 add_link_options(-T ${LINKER_SCRIPT})
diff --git a/app/app.c b/app/app.c
index 5383e48..017911b 100644
--- a/app/app.c
+++ b/app/app.c
@@ -16,17 +16,8 @@ void loop() {
 }
 
 void app() {
-    volatile uint8_t sendData[8];
-    volatile uint8_t bytesToSend = 8;
-    // Счетчик отправленных байт
-    volatile uint8_t sendDataCounter = 0;
-    for (uint8_t i = 0; i < 8; i++)
-    {
-        sendData[i] = i;
-    }
-    // USART_ITConfig(USART2, USART_IT_TC, ENABLE);
     while(1) {
-        USART_SendData(USART2, sendData[sendDataCounter++ % 8]);
+        printf("Hello, world%.6f\r\n", 5.432);
         loop();
     };
 }
diff --git a/bsp/bsp.c b/bsp/bsp.c
index 4b53e32..f8653e6 100644
--- a/bsp/bsp.c
+++ b/bsp/bsp.c
@@ -10,6 +10,36 @@
 /* USB OTG FS, SDIO and RNG Clock =  PLL_VCO / PLLQ */
 #define PLL_Q      7
 
+// #ifdef __GNUC__
+// #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
+// #else
+// #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
+// #endif /* __GNUC__ */
+
+// PUTCHAR_PROTOTYPE
+// {
+//     for(uint8_t i = 0; i < len; ++i) {
+//         USART_SendData(USART2, ptr[i]);
+//     }
+//   return ch;
+// }
+
+int _write(int fd, char* ptr, int len) {
+    int i= 0;
+    while(i < len) {
+        while (USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET); // Ждем, пока буфер передатчика не освободится
+        USART_SendData(USART2, *ptr++); // Отправляем символ
+        i++;
+    }
+    
+    return len;
+}
+
+void UART_SendString(const char* str) {
+  while (*str) {
+
+  }
+}
 
 
 
diff --git a/bsp/bsp.h b/bsp/bsp.h
index 5bbfbca..c2e5df6 100644
--- a/bsp/bsp.h
+++ b/bsp/bsp.h
@@ -5,6 +5,7 @@
 #include "stm32f4xx_gpio.h"
 #include "stm32f4xx_rcc.h"
 #include "stm32f4xx_usart.h"
+#include <stdio.h> 
 
 void board_init();