feat: usart retarget

Core/Src/main.c

@@ -27,6 +27,7 @@
 /* USER CODE BEGIN Includes */
 #include <stdio.h>
 
+#include "retarget.h"
 #include "oled.h"
 #include "rc522.h"
 /* USER CODE END Includes */
@@ -119,13 +120,19 @@ int main(void)
   MX_USART1_UART_Init();
   MX_SPI1_Init();
   /* USER CODE BEGIN 2 */
+  // Retarget uart
+  RetargetInit(&huart1);
+
+  // Init RC522
   MFRC_Init();
   PCD_Reset();
 
+  // Init OLED
   OLED_Init();
   OLED_Clear();
 
   OLED_ShowString(0,0,"Card scan...",12);
+  printf("startup\n");
   /* USER CODE END 2 */
 
   /* Infinite loop */